Rising temperatures reduce global wheat production

Future of durum wheat research and breeding: Insights from early career researchers

Durum wheat (Triticum turgidum ssp. durum) is globally cultivated for pasta, couscous, and bulgur production. With the changing climate and growing world population, the need to significantly increase durum production to meet the anticipated demand is paramount. This review summarizes recent advancements in durum research, encompassing the exploitation of existing and novel genetic diversity, exploration of potential new diversity sources, breeding for climate-resilient varieties, enhancements in production and management practices, and the utilization of modern technologies in breeding and cultivar development. In comparison to bread wheat (T. aestivum), the durum wheat community and production area are considerably smaller, often comprising many small-family farmers, notably in African and Asian countries. Public breeding programs such as the International Maize and Wheat Improvement Center (CIMMYT) and the International Center for Agricultural Research in the Dry Areas (ICARDA) play a pivotal role in providing new and adapted cultivars for these small-scale growers. We spotlight the contributions of these and others in this review. Additionally, we offer our recommendations on key areas for the durum research community to explore in addressing the challenges posed by climate change while striving to enhance durum production and sustainability. As part of the Wheat Initiative, the Expert Working Group on Durum Wheat Genomics and Breeding recognizes the significance of collaborative efforts in advancing toward a shared objective. We hope the insights presented in this review stimulate future research and deliberations on the trajectory for durum wheat genomics and breeding.

Potential global distribution of Setaria italica, an important species for dryland agriculture in the context of climate change

Setaria italica (S. italica, Linnaeus, 1753) is a drought-resistant, barren-tolerant, and widely adapted C-4 crop that plays a vital role in maintaining agricultural and economic stability in arid and barren regions of the world. However, the potential habitat of S. italica under current and future climate scenarios remains to be explored. Predicting the potential global geographic distribution of S. italica and clarifying its ecological requirements can help promote sustainable agriculture, which is crucial for addressing the global food crisis. In this study, we predicted the potential global geographic distribution of S. italica based on 3,154 global distribution records using the Maxent model and ArcGIS software. We assessed the constraints on its potential distribution based on the contribution of environmental factors variables. The predictive accuracy of the Maxent model was evaluated using AUC values, TSS values, and Kappa statistics, respectively. The results showed that the Maxent model had a high prediction accuracy, and the simulation results were also reliable; the total suitable habitats of S. italica is 5.54×107 km2, which mainly included the United States (North America), Brazil (South America), Australia (Oceania), China, India (Asia), and the Russian Federation (Europe). The most suitable habitat of S. italica was 0.52×107 km2, accounting for 9.44% of the total areas, mainly in the United States, India, the Russian Federation, and China. Soil and precipitation (driest monthly precipitation, hottest seasonal precipitation) are the most critical factors limiting the potential distribution of S. italica. Compared with the modern potential distribution, we predict that the four future climate change scenarios will result in varying reductions in the possible geographic ranges of S. italica. Overall, climate change may significantly affect the global distribution of S. italica, altering its worldwide production and trade patterns.

Genome-wide expression analysis of novel heat-responsive microRNAs and their targets in contrasting wheat genotypes at reproductive stage under terminal heat stress

Introduction

Heat stress at terminal stage of wheat is critical and leads to huge yield losses worldwide. microRNAs (miRNAs) play significant regulatory roles in gene expression associated with abiotic and biotic stress at the post-transcriptional level.

Methods

In the present study, we carried out a comparative analysis of miRNAs and their targets in flag leaves as well as developing seeds of heat tolerant (RAJ3765) and heat susceptible (HUW510) wheat genotypes under heat stress and normal conditions using small RNA and degradome sequencing.

Results and discussion

A total of 84 conserved miRNAs belonging to 35 miRNA families and 93 novel miRNAs were identified in the 8 libraries. Tae-miR9672a-3p, tae-miR9774, tae-miR9669-5p, and tae-miR5048-5p showed the highest expression under heat stress. Tae-miR9775, tae-miR9662b-3p, tae-miR1120a, tae-miR5084, tae-miR1122a, tae-miR5085, tae-miR1118, tae-miR1130a, tae-miR9678-3p, tae-miR7757-5p, tae-miR9668-5p, tae-miR5050, tae-miR9652-5p, and tae-miR9679-5p were expressed only in the tolerant genotype, indicating their role in heat tolerance. Comparison between heat-treated and control groups revealed that 146 known and 57 novel miRNAs were differentially expressed in the various tissues. Eight degradome libraries sequence identified 457 targets of the differentially expressed miRNAs. Functional analysis of the targets indicated their involvement in photosynthesis, spliceosome, biosynthesis of nucleotide sugars and protein processing in the endoplasmic reticulum, arginine and proline metabolism and endocytosis.

Conclusion

This study increases the number of identified and novel miRNAs along with their roles involved in heat stress response in contrasting genotypes at two developing stages of wheat.

Simulating the effects of optimizing sowing date and variety shift on maize production at finer scale in northeast China under future climate

BACKGROUND

Global warming and the rising occurrences of climate extremes have become formidable challenges for maize production in northeast China. The optimization of sowing date and variety choice stand out as two economic approaches for maize to enhance its resilience to climate change. Nevertheless, assessment of the potential of optimizing sowing date and variety shift on maize yield at finer scale remains underexamined. This study investigated the implications of optimizing sowing date and implementing variety shift on maize yield from a regional perspective.

RESULTS

Compared to the reference period (1986-2005), climate change would decrease by 11.5-34.6% (the range describes the differences among climate scenarios and agro-ecological regions) maize yield in the 2050s (2040-2059) if no adaption measure were to be implemented. The combined adaption (optimizing sowing date and variety shift) can improve maize yield by 38.8 ± 11.3%, 42.7 ± 9.7% and 33.9 ± 7.6% under the SSP1-2.6, SSP2-4.5 and SSP5-8.5 scenarios, respectively. The current sowing window typically falls within the projected optimal sowing window, defined as the period capable of achieving 90% of the maximum yield within the potential sowing window under future climate conditions. Consequently, the potential of the effect of optimizing sowing window on maize yield is limited. In contrast, variety shift results in higher yield improvement, as temperature rise creates favorable conditions for transplanting varieties with an extended growth period, particularly in high latitudes and mountainous regions. Under future climate, cumulative precipitation and compound drought and hot days during maize growing seasons are two key factors influencing maize production.

CONCLUSIONS

The optimization of sowing date and variety choice can improve maize yield in northeast China. In addition, maize production should consider varieties with longer growth period and drought and heat tolerance to adapt to climate change. © 2023 Society of Chemical Industry.

Is CRISPR/Cas9-based multi-trait enhancement of wheat forthcoming?

Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) technologies have been implemented in recent years in the genome editing of eukaryotes, including plants. The original system of knocking out a single gene by causing a double-strand break (DSB), followed by non-homologous end joining (NHEJ) or Homology-directed repair (HDR) has undergone many adaptations. These adaptations include employing CRISPR/Cas9 to upregulate gene expression or to cause specific small changes to the DNA sequence of the gene-of-interest. In plants, multiplexing, i.e., inducing multiple changes by CRISPR/Cas9, is extremely relevant due to the redundancy of many plant genes, and the time- and labor-consuming generation of stable transgenic plant lines via crossing. Here we discuss relevant examples of various traits, such as yield, biofortification, gluten content, abiotic stress tolerance, and biotic stress resistance, which have been successfully manipulated using CRISPR/Cas9 in plants. While existing studies have primarily focused on proving the impact of CRISPR/Cas9 on a single trait, there is a growing interest among researchers in creating a multi-stress tolerant wheat cultivar 'super wheat', to commercially and sustainably enhance wheat yields under climate change. Due to the complexity of the technical difficulties in generating multi-target CRISPR/Cas9 lines and of the interactions between stress responses, we propose enhancing already commercial local landraces with higher yield traits along with stress tolerances specific to the respective localities, instead of generating a general 'super wheat'. We hope this will serve as the sustainable solution to commercially enhancing crop yields under both stable and challenging environmental conditions.

Climate change enhances stability of wheat-flowering-date

The stability of winter wheat-flowering-date is crucial for ensuring consistent and robust crop performance across diverse climatic conditions. However, the impact of climate change on wheat-flowering-dates remains uncertain. This study aims to elucidate the influence of climate change on wheat-flowering-dates, predict how projected future climate conditions will affect flowering date stability, and identify the most stable wheat genotypes in the study region. We applied a multi-locus genotype-based (MLG-based) model for simulating wheat-flowering-dates, which we calibrated and evaluated using observed data from the Northern China winter wheat region (NCWWR). This MLG-based model was employed to project flowering dates under different climate scenarios. The simulated flowering dates were then used to assess the stability of flowering dates under varying allelic combinations in projected climatic conditions. Our MLG-based model effectively simulated flowering dates, with a root mean square error (RMSE) of 2.3 days, explaining approximately 88.5 % of the genotypic variation in flowering dates among 100 wheat genotypes. We found that, in comparison to the baseline climate, wheat-flowering-dates are expected to shift earlier within the target sowing window by approximately 11 and 14 days by 2050 under the Representative Concentration Pathways 4.5 (RCP4.5) and RCP8.5 climate scenarios, respectively. Furthermore, our analysis revealed that wheat-flowering-date stability is likely to be further strengthened under projected climate scenarios due to early flowering trends. Ultimately, we demonstrate that the combination of Vrn and Ppd genes, rather than individual Vrn or Ppd genes, plays a critical role in wheat-flowering-date stability. Our results suggest that the combination of Ppd-D1a with winter genotypes carrying the vrn-D1 allele significantly contributes to flowering date stability under current and projected climate scenarios. These findings provide valuable insights for wheat breeders and producers under future climatic conditions.

Genome-wide scanning to identify and validate single nucleotide polymorphism markers associated with drought tolerance in spring wheat seedlings

Unlike other growth stages of wheat, very few studies on drought tolerance have been done at the seedling stage, and this is due to the complexity and sensitivity of this stage to drought stress resulting from climate change. As a result, the drought tolerance of wheat seedlings is poorly understood and very few genes associated with drought tolerance at this stage were identified. To address this challenge, a set of 172 spring wheat genotypes representing 20 different countries was evaluated under drought stress at the seedling stage. Drought stress was applied on all tested genotypes by water withholding for 13 days. Two types of traits, namely morphological and physiological traits were scored on the leaves of all tested genotypes. Genome-wide association study (GWAS) is one of the effective genetic analysis methods that was used to identify target single nucleotide polymorphism (SNP) markers and candidate genes for later use in marker-assisted selection. The tested plant materials were genotyped using 25k Infinium iSelect array (25K) (herein after it will be identified as 25K) (for 172 genotypes) and genotyping-by-sequencing (GBS) (for 103 genotypes), respectively. The results of genotyping revealed 21,093 25K and 11,362 GBS-SNPs, which were used to perform GWAS analysis for all scored traits. The results of GWAS revealed that 131 and 55 significant SNPs were controlling morphological and physiological traits, respectively. Moreover, a total of eight and seven SNP markers were found to be associated with more than one morphological and physiological trait under drought stress, respectively. Remarkably, 10 significant SNPs found in this study were previously reported for their association with drought tolerance in wheat. Out of the 10 validated SNP markers, four SNPs were associated with drought at the seedling stage, while the remaining six SNPs were associated with drought stress at the reproductive stage. Moreover, the results of gene enrichment revealed 18 and six pathways as highly significant biological and molecular pathways, respectively. The selection based on drought-tolerant alleles revealed 15 genotypes with the highest number of different drought-tolerant alleles. These genotypes can be used as candidate parents in future breeding programs to produce highly drought-tolerant genotypes with high genetic diversity. Our findings in this study provide novel markers and useful information on the genetic basis of drought tolerance at early growth stages.

Natural variation of STKc_GSK3 kinase TaSG-D1 contributes to heat stress tolerance in Indian dwarf wheat

Heat stress threatens global wheat (Triticum aestivum) production, causing dramatic yield losses worldwide. Identifying heat tolerance genes and comprehending molecular mechanisms are essential. Here, we identify a heat tolerance gene, TaSG-D1E286K, in Indian dwarf wheat (Triticum sphaerococcum), which encodes an STKc_GSK3 kinase. TaSG-D1E286K improves heat tolerance compared to TaSG-D1 by enhancing phosphorylation and stability of downstream target TaPIF4 under heat stress condition. Additionally, we reveal evolutionary footprints of TaPIF4 during wheat selective breeding in China, that is, InDels predominantly occur in the TaPIF4 promoter of Chinese modern wheat cultivars and result in decreased expression level of TaPIF4 in response to heat stress. These sequence variations with negative effect on heat tolerance are mainly introduced from European germplasm. Our study provides insight into heat stress response mechanisms and proposes a potential strategy to improve wheat heat tolerance in future.

Biomolecular evidence for changing millet reliance in Late Bronze Age central Germany

The Bronze Age of Central Europe was a period of major social, economic, political and ideological change. The arrival of millet is often seen as part of wider Bronze Age connectivity, yet understanding of the subsistence regimes underpinning this dynamic period remains poor for this region, in large part due to a dominance of cremation funerary rites, which hinder biomolecular studies. Here, we apply stable isotope analysis, radiocarbon dating and archaeobotanical analysis to two Late Bronze Age (LBA) sites, Esperstedt and Kuckenburg, in central Germany, where human remains were inhumed rather than cremated. We find that people buried at these sites did not consume millet before the Middle Bronze Age (MBA) (ca. 1600 BCE). However, by the early LBA (ca. 1300-1050 BCE) people consumed millet, often in substantial quantities. This consumption appears to have subsequently diminished or ceased around 1050-800 BCE, despite charred millet grains still being found in the archaeological deposits from this period. The arrival of millet in this region, followed by a surge in consumption spanning two centuries, indicates a complex interplay of cultural and economic factors, as well as a potential use of millet to buffer changes in aridity in a region increasingly prone to crop failure in the face of climate change today.

Projecting global fertilizer consumption under shared socioeconomic pathway (SSP) scenarios using an approach of ensemble machine learning

Comprehensively projecting global fertilizer consumption is essential for providing critical datasets in related fields such as earth system simulation, the fertilizer industry, and agricultural sciences. However, since previous studies have not fully considered the socioeconomic factors affecting fertilizer consumption, huge uncertainties may remain in fertilizer consumption projections. Here, an approach ensembled six machine learning algorithms was proposed in this study to predict global fertilizer consumption from 2020 to 2100 by considering the impact of socioeconomic factors under shared socioeconomic pathway (SSP) scenarios. It indicates that the proposed approach provides a rational and reliable framework for fertilizer consumption prediction that stably outperforms the single algorithms with relatively high accuracy (Nash-Sutcliffe efficiency of 0.93, Kling-Gupta efficiency of 0.89, and mean absolute percentage error of 10.97 %). We found that global N and P fertilizer consumption may decrease from 2020 to 2100, while K fertilizer may buck the trend. N fertilizer consumption showed a declining trend of -1 %, -17.13 %, and -3.43 % under the SSP1, SSP2, and SSP3 scenarios in 2100, respectively. For P fertilizer, those were -0.68 %, -9.68 %, and -2.03 %. In contrast, global K fertilizer consumption may increase by 18.03 %, 9.18 %, and 6.74 %, respectively. On average, N, P, and K fertilizer consumption is highest in China, and the lowest is in Kazakhstan. However, the hotspots of N fertilizer consumption may shift from China to Latin America and the Caribbean. This study highlighted the ensemble machine learning approach could potentially be a robust method for predicting future fertilizer consumption. Our prediction product will not only contribute to a better understanding of global fertilizer consumption trends and dynamics but also provide flexible and accurate key data/parameters for related research. The Projected Global Fertilizers Consumption Datasets are available at doi:https://doi.org/10.5281/zenodo.8195593 (Gao et al., 2023).

The influence of climatic and environmental variables on sunflower planting season suitability in Tanzania

Crop survival and growth requires identification of correlations between appropriate suitable planting season and relevant climatic and environmental characteristics. Climatic and environmental conditions may cause water and heat stress at critical stages of crop development and thus affecting planting suitability. Consequently, this may affect crop yield and productivity. This study assesses the influence of climate and environmental variables on rain-fed sunflower planting season suitability in Tanzania. Data on rainfall, temperature, slope, elevation, soil and land use/or cover were accessed from publicly available sources using Google Earth Engine. This is a cloud-based geospatial computing platform for remote sensed datasets. Tanzania sunflower production calendar of 2022 was adopted to mark the start and end limits of planting across the country. The default climate and environmental parameters from FAO database were used. In addition, Pearson correlation was used to evaluate the relationship between rainfall, temperature over Normalized Difference Vegetation Index (NDVI) from 2000 to 2020 at five-year interval for January-April and June-September, for high and poor suitability season. The results showed that planting suitability of sunflower in Tanzania is driven more by rainfall than temperature. It was revealed that intra-annual planting suitability increases gradually from short to long- rain season and diminishes towards dry season of the year. January-April planting season window showing highest suitability (41.65%), whereas June-September indicating lowest suitability (0.05%). Though, not statistically significant, rainfall and NDVI were positively correlated with r = 0.65 and 0.75 whereas negative correlation existed between temperature and NDVI with r = -- 0.6 and - 0.77. We recommend sunflower subsector interventions that consider appropriate intra-regional and seasonal diversity as an important adaptive mechanism to ensure high sunflower yields.

Insight into carbohydrate metabolism, protein quantification and mineral regulation in wheat (Triticum aestivum L.) by the action of green synthesized silver nanoparticles (AgNPs) against heat stress

In the present investigation, the role of GS-AgNPs treatment in wheat plants was carried out in reducing heat stress with the aim of facilitating scientists on this topic. The effect of GS-AgNPs against heat stress has rarely been deliberated in wheat plants, and only a few studies have been established earlier in this scenario. This work illustrated the effect of GS-AgNPs on the regulation of carbohydrates metabolism, SOD, proteins, crude fibers, and minerals changes in wheat plants. Data were analysed using PCA analysis, correlation parameters, and normal probability distribution in PAST 3 software. The results indicated that heat stress alone caused severe changes in carbohydrates metabolism, SOD, proteins, crude fibers, and minerals immediately so that plants could not recover without foreign stabilizers such as GS-AgNPs. The application of GS-AgNPs increases the flux of carbohydrates metabolism, SOD, and proteins, including HSPs, crude fibers, and minerals, in wheat plants to reduce the effect of heat stress. The 50 mg/l concentration of GS-AgNPs has shown an increase in carbohydrates metabolism and SOD activity, while crude fibres have shown a significant enhancement at 100 mg/l of GS-AgNPs. The crude and true proteins were also shown pronounced increase in treatment to a concentration of 50 mg/l of GS-AgNPs. GS-AgNPs stimulated HSP production; most importantly, smHSP production was observed in the present results with other HSPs in wheat plants treated with a 50 mg/l concentration of GS-AgNPs. The mineral distribution was also regulated by the respective treatment of GS-AgNPs, and the highest amounts of Ca, P and Fe were found to be highest in wheat under heat stress. In general, we computed the expected model based on GS-AgNPs on the genes/factors that respond to heat stress and their potential role in mitigating heat stress in wheat. In addition, we discussed the prospective signalling pathway triggered by GS-AgNPs in wheat against heat stress. In the future, this work might be helpful in distinguishing the genetic variation due to GS-AgNPs in promoting tolerance in wheat against heat stress.Communicated by Ramaswamy H. Sarma.

Identifying long non-coding RNAs involved in heat stress response during wheat pollen development

Introduction

Wheat is a staple food crop for over one-third of the global population. However, the stability of wheat productivity is threatened by heat waves associated with climate change. Heat stress at the reproductive stage can result in pollen sterility and failure of grain development.

Methods

This study used transcriptome data analysis to explore the specific expression of long non-coding RNAs (lncRNAs) in response to heat stress during pollen development in four wheat cultivars.

Results and discussion

We identified 11,054 lncRNA-producing loci, of which 5,482 lncRNAs showed differential expression in response to heat stress. Heat-responsive lncRNAs could target protein-coding genes in cis and trans and in lncRNA-miRNA-mRNA regulatory networks. Gene ontology analysis predicted that target protein-coding genes of lncRNAs regulate various biological processes such as hormonal responses, protein modification and folding, response to stress, and biosynthetic and metabolic processes. We also noted some paired lncRNA/protein-coding gene modules and some lncRNA-miRNA-mRNA regulatory modules shared in two or more wheat cultivars. These modules were related to regulating plant responses to heat stress, such as heat-shock proteins and transcription factors, and protein domains, such as MADS-box, Myc-type, and Alpha crystallin/Hsp20 domain.

Conclusion

Our results provide the basic knowledge and molecular resources for future functional studies investigating wheat reproductive development under heat stress.

Differential effects of elevated CO2 on awn and glume metabolism in durum wheat (Triticum durum)

While the effect of CO2 enrichment on wheat (Triticum spp.) photosynthesis, nitrogen content or yield has been well-studied, the impact of elevated CO2 on metabolic pathways in organs other than leaves is poorly documented. In particular, glumes and awns, which may refix CO2 respired by developing grains and be naturally exposed to higher-than-ambient CO2 mole fraction, could show specific responses to elevated CO2 . Here, we took advantage of a free-air CO2 enrichment experiment and performed multilevel analyses, including metabolomics, ionomics, proteomics, major hormones and isotopes in Triticum durum . While in leaves, elevated CO2 tended to accelerate amino acid metabolism with many significantly affected metabolites, the effect on glumes and awns metabolites was modest. There was a lower content in compounds of the polyamine pathway (along with uracile and allantoin) under elevated CO2 , suggesting a change in secondary N metabolism. Also, cytokinin metabolism appeared to be significantly affected under elevated CO2 . Despite this, elevated CO2 did not affect the final composition of awn and glume organic matter, with the same content in carbon, nitrogen and other elements. We conclude that elevated CO2 mostly impacts on leaf metabolism but has little effect in awns and glumes, including their composition at maturity.

A framework for modeling an agronomic system's vulnerability to climate change with reflections from the Caspian coastal agro-ecological zone of Iran

Assessing the vulnerability of different sectors to climate change has great importance in determining the appropriate adaptation measures to deal with climate change impacts on a river basin scale. In this research, using a framework for modeling the agronomic system vulnerability to climate change, vulnerability assessment under different scenarios was conducted for the Gorganrud River Basin located in the agro-ecological zone of the Caspian coastal plain of Iran. Considering exposure, susceptibility, and lack of resilience components, 12 indicators were chosen and quantified for both agronomic-environmental and socio-economic aspects. The SSM-iCrop2 model was used to simulate crop yield under current and climate change scenarios across the basin. The analysis indicates that in the current condition, the vulnerability level is different across the watersheds of the Gorganrud River Basin. By applying the climate change scenarios, agronomic system vulnerability would increase in the basin to some extent, particularly in Madarsu and Tilabad watersheds attributed with high vulnerability (0.63 and 0.61, respectively). This justifies the need to implement adaptation plans for encountering water shortage in the future. The analysis also suggests that the vulnerability of the agronomic system for adaptation scenarios characterized by less water consumption under climate change conditions is going to be slightly different from the vulnerability under the climate change scenarios. Due to an increase in agronomic system vulnerability under climate change scenarios, coupled with the fact that most watersheds (except Chehelchai, Nardin, and Narmab) are moderately vulnerable even under current conditions, policymakers and planners should promote crop and livelihood diversification programs aiming to prevent an increase in agronomic vulnerability.

Exploring the genotype-environment interaction of bread wheat in ambient and high-temperature planting conditions: a rigorous investigation

The current study is carried out to find out the stable wheat genotype in ambient and high temperature planting conditions. The objective was to estimate the genotype x environment interactions through various univariates and multivariate techniques. Twenty wheat genotypes were evaluated at Jabalpur, Narmadapuram, and Sagar districts of Madhya Pradesh, India, across cropping years 2019-20 and 2021-21, considering both timely and late planting conditions. The univariate and multivariate stability analysis were performed based on per-plant grain yield and grain filling rate. Our result revealed that environment, genotype, and GEI effects were significant (P < 0.001) across all the environments. The wheat genotypes JW3288, L8, and L13 have been discerned as top performers, exhibiting remarkable stability in grain yield per plant. Similarly, for grain filling rate, genotypes L11 and L13 have emerged as superior and consistently stable performers. Notably, the AMMI and GGE models demonstrated superior effectiveness and accuracy compared to the linear regression model. In conclusion, based on thorough univariate and multivariate stability analyses, L13 emerges as the most stable genotype across all environments under both planting conditions. Consequently, L13 holds promise for inclusion in future breeding programs. It's noteworthy that Jabalpur stands out as the most discriminating and representative environment among all the conditions assessed.

QTL mapping: insights into genomic regions governing component traits of yield under combined heat and drought stress in wheat

Drought and heat frequently co-occur during crop growth leading to devastating yield loss. The knowledge of the genetic loci governing component traits of yield under combined drought and heat stress is essential for enhancing the climate resilience. The present study employed a mapping population of 180 recombinant inbred lines (RILs) derived from a cross between GW322 and KAUZ to identify quantitative trait loci (QTLs) governing the component traits of yield under heat and combined stress conditions. Phenotypic evaluation was conducted across two consecutive crop seasons (2021-2022 and 2022-2023) under late sown irrigation (LSIR) and late sown restricted irrigation (LSRI) conditions at the Indian Council of Agricultural Research Institute-Indian Agricultural Research Institute (ICAR-IARI), New Delhi. Various physiological and agronomic traits of importance were measured. Genotyping was carried out with 35K SNP Axiom breeder's genotyping array. The linkage map spanned a length of 6769.45 cM, ranging from 2.28 cM/marker in 1A to 14.21 cM/marker in 5D. A total of 35 QTLs were identified across 14 chromosomes with 6B containing the highest (seven) number of QTLs. Out of 35 QTLs, 16 were major QTLs explaining the phenotypic variance greater than 10%. The study identified eight stable QTLs along with two hotspots on chromosomes 6B and 5B. Five QTLs associated with traits thousand-grain weight (TGW), normalized difference vegetation index (NDVI), and plant height (PH) were successfully validated. Candidate genes encoding antioxidant enzymes, transcription factors, and growth-related proteins were identified in the QTL regions. In silico expression analysis highlighted higher expression of transcripts TraesCS2D02G021000.1, TraesCS2D02G031000, TraesCS6A02G247900, and TraesCS6B02G421700 under stress conditions. These findings contribute to a deeper understanding of the genetic architecture underlying combined heat and drought tolerance in wheat, providing valuable insights for wheat improvement strategies under changing climatic conditions.

Plants and global warming: challenges and strategies for a warming world

KEY MESSAGE

In this review, we made an attempt to create a holistic picture of plant response to a rising temperature environment and its impact by covering all aspects from temperature perception to thermotolerance. This comprehensive account describing the molecular mechanisms orchestrating these responses and potential mitigation strategies will be helpful for understanding the impact of global warming on plant life. Organisms need to constantly recalibrate development and physiology in response to changes in their environment. Climate change-associated global warming is amplifying the intensity and periodicity of these changes. Being sessile, plants are particularly vulnerable to variations happening around them. These changes can cause structural, metabolomic, and physiological perturbations, leading to alterations in the growth program and in extreme cases, plant death. In general, plants have a remarkable ability to respond to these challenges, supported by an elaborate mechanism to sense and respond to external changes. Once perceived, plants integrate these signals into the growth program so that their development and physiology can be modulated befittingly. This multifaceted signaling network, which helps plants to establish acclimation and survival responses enabled their extensive geographical distribution. Temperature is one of the key environmental variables that affect all aspects of plant life. Over the years, our knowledge of how plants perceive temperature and how they respond to heat stress has improved significantly. However, a comprehensive mechanistic understanding of the process still largely elusive. This review explores how an increase in the global surface temperature detrimentally affects plant survival and productivity and discusses current understanding of plant responses to high temperature (HT) and underlying mechanisms. We also highlighted potential resilience attributes that can be utilized to mitigate the impact of global warming.

Meiotic instability and irregular chromosome pairing underpin heat-induced infertility in bread wheat carrying the Rht-B1b or Rht-D1b Green Revolution genes

Mutations in the Rht-B1a and Rht-D1a genes of wheat (Triticum aestivum; resulting in Rht-B1b and Rht-D1b alleles) cause gibberellin-insensitive dwarfism and are one of the most important elements of increased yield introduced during the 'Green Revolution'. We measured the effects of a short period of heat imposed during the early reproductive stage on near-isogenic lines carrying Rht-B1b or Rht-D1b alleles, with respect to the wild-type (WT). The temperature shift caused a significant fertility loss within the ears of Rht-B1b and Rht-D1b wheats, greater than that observed for the WT. Defects in chromosome synapsis, reduced homologous recombination and a high frequency of chromosome mis-segregation were associated with reduced fertility. The transcription of TaGA3ox gene involved in the final stage of gibberellic acid (GA) biosynthesis was activated and ultra-performance liquid chromatography-tandem mass spectrometry identified GA1 as the dominant bioactive GA in developing ears, but levels were unaffected by the elevated temperature. Rht-B1b and Rht-D1b mutants were inclined to meiotic errors under optimal temperatures and showed a higher susceptibility to heat than their tall counterparts. Identification and introduction of new dwarfing alleles into modern breeding programmes is invaluable in the development of climate-resilient wheat varieties.

Heat and Wheat: Adaptation strategies with respect to heat shock proteins and antioxidant potential; an era of climate change

Extreme changes in weather including heat-wave and high-temperature fluctuations are predicted to increase in intensity and duration due to climate change. Wheat being a major staple crop is under severe threat of heat stress especially during the grain-filling stage. Widespread food insecurity underscores the critical need to comprehend crop responses to forthcoming climatic shifts, pivotal for devising adaptive strategies ensuring sustainable crop productivity. This review addresses insights concerning antioxidant, physiological, molecular impacts, tolerance mechanisms, and nanotechnology-based strategies and how wheat copes with heat stress at the reproductive stage. In this study stress resilience strategies were documented for sustainable grain production under heat stress at reproductive stage. Additionally, the mechanisms of heat resilience including gene expression, nanomaterials that trigger transcription factors, (HSPs) during stress, and physiological and antioxidant traits were explored. The most reliable method to improve plant resilience to heat stress must include nano-biotechnology-based strategies, such as the adoption of nano-fertilizers in climate-smart practices and the use of advanced molecular approaches. Notably, the novel resistance genes through advanced molecular approach and nanomaterials exhibit promise for incorporation into wheat cultivars, conferring resilience against imminent adverse environmental conditions. This review will help scientific communities in thermo-tolerance wheat cultivars and new emerging strategies to mitigate the deleterious impact of heat stress.

Climatic variability and its impact on the indigenous agricultural system using panel data analysis in the Sikkim Himalaya, India

Climate-induced extreme events with fluctuations in climatic indicators like temperature and precipitation highly influence crop productivity. This study deals with quantitative analysis of climatic variability and crop production (1990-2018) using panel data regression analysis. The focus is on variability of three crops, i.e., paddy, maize, and wheat in the Rangit river basin of Sikkim Himalaya, India. Meterological data were acquired from the Indian Meteorological Department, agricultural data from the state agricultural department and a field survey were also conducted with the farmers, using a structured questionnaire, focused group discussion, and key informant observations. The acquired data was analyzed with the help of correlation and multiple linear regression analysis to analyze the relationship between climatic variability and crop production. The result of the study shows that all three crops are dependent on rainfall; however, paddy was the most sensitive to climatic variability. It was found that the overall grain production had an inverse relation to temperature, but it had a positive correlation with rainfall. It was observed that there was a continuous decline in the overall production of paddy and wheat. During deficiency years, it was found that when - 11.33% rainfall was deficient, paddy yield declined by - 1.52%. Further, a deviation of - 13.48% led to a decline of - 54.78% in wheat. The study advocates that timely policy interventions and strategies shall reduce climatic shocks and improve productivity. This would strengthen the livelihood security of the local communities, overcome the challenges of food security, and ensure long-term sustainability of Rangit River basin.

Building soil to reduce climate change impacts on global crop yield

Improving soil health and resilience is fundamental for sustainable food production, however the role of soil in maintaining or improving global crop productivity under climate warming is not well identified and quantified. Here, we examined the impact of soil on yield response to climate warming for four major crops (i.e., maize, wheat, rice and soybean), using global-scale datasets and random forest method. We found that each °C of warming reduced global yields of maize by 3.4%, wheat by 2.4%, rice by 0.3% and soybean by 5.0%, which were spatially heterogeneous with possible positive impacts. The random forest modeling analyses further showed that soil organic carbon (SOC), as an indicator of soil quality, dominantly explained the spatial heterogeneity of yield responses to warming and would regulate the negative warming responses. Improving SOC under the medium SOC sequestration scenario would reduce the warming-induced yield loss of maize, wheat, rice and soybean to 0.1% °C-1, 2.7% °C-1, 3.4% °C-1 and - 0.6% °C-1, respectively, avoiding an average of 3%-5% °C-1 of global yield loss. These yield benefits would occur on 53.2%, 67.8%, 51.8% and 71.6% of maize, wheat, rice and soybean planting areas, respectively, with particularly pronounced benefits in the regions with negative warming responses. With improved soil carbon, food systems are predicted to provide additional 20 to over 130 million tonnes of food that would otherwise lose due to future warming. Our findings highlight the critical role of soil in alleviating negative warming impacts on food security, especially for developing regions, given that sustainable actions on soil improvement could be taken broadly.

Jasmonate: A Hormone of Primary Importance for Temperature Stress Response in Plants

Temperature is a critical environmental factor that plays a vital role in plant growth and development. Temperatures below or above the optimum ranges lead to cold or heat stress, respectively. Temperature stress retards plant growth and development, and it reduces crop yields. Jasmonates (JAs) are a class of oxylipin phytohormones that play various roles in growth, development, and stress response. In recent years, studies have demonstrated that cold and heat stress affect JA biosynthesis and signaling, and JA plays an important role in the response to temperature stress. Recent studies have provided a large body of information elucidating the mechanisms underlying JA-mediated temperature stress response. In the present review, we present recent advances in understanding the role of JA in the response to cold and heat stress, and how JA interacts with other phytohormones during this process.

Enhancing climate change resilience in agricultural crops

Climate change threatens global food and nutritional security through negative effects on crop growth and agricultural productivity. Many countries have adopted ambitious climate change mitigation and adaptation targets that will exacerbate the problem, as they require significant changes in current agri-food systems. In this review, we provide a roadmap for improved crop production that encompasses the effective transfer of current knowledge into plant breeding and crop management strategies that will underpin sustainable agriculture intensification and climate resilience. We identify the main problem areas and highlight outstanding questions and potential solutions that can be applied to mitigate the impacts of climate change on crop growth and productivity. Although translation of scientific advances into crop production lags far behind current scientific knowledge and technology, we consider that a holistic approach, combining disciplines in collaborative efforts, can drive better connections between research, policy, and the needs of society.

Future climate change impacts on wheat grain yield and protein in the North China Region

The threat of global climate change on wheat production may be underestimated by the limited capacity of many crop models to predict grain quality and protein composition. This study aimed to integrate a wheat quality module of protein components into the CROPSIM-CERES-Wheat model to investigate the impact of climate change on wheat grain yield and protein quality in the North China Region (NCR) using five Global Climate Models (GCMs) from CMIP6 under three shared socioeconomic pathways. The CERES-Wheat model with a quality module was developed and calibrated and validated using data from several sites in the NCR. The results of the calibration and validation showed that the modified CERES-Wheat model can accurately predict grain yield, protein content and its components in field experiments. Compared with the baseline period (1981-2010), the annual mean temperature and annual cumulative precipitation increased in the NCR in the 2030's, 2050's and 2080's. The radiation was higher under the SSP126 and SSP585 scenarios, and lower under the SSP370 scenario compared to the baseline period. The anthesis and maturity date occurred earlier under the three future scenarios. The average grain yield increased by 13.3-30.9 % under three future scenarios. However, the regional average grain protein content of winter wheat in the future decreased by 2.0 %- 3.5 %. The reduction in wheat grain protein at the regional was less pronounced under SSP370 than that under SSP126 and SSP585. The structural protein content of winter wheat decreased under future climate conditions compared with the baseline period, but the storage protein content showed the opposite tendency. The model provided a useful tool to study the effects of future climate on grain quality and protein composition. These findings are important for developing agricultural practices and strategies to mitigate the potential impacts of climate change on wheat production and wheat quality in the future.

Heat-dependent postpollination limitations on maize pollen tube growth and kernel sterility

Heat stress has a negative impact on pollen development in maize (Zea mays L.) but the postpollination events that determine kernel sterility are less well characterised. The impact of short-term (hours) heat exposure during postpollination was therefore assessed in silks and ovaries. The temperatures inside the kernels housed within the husks was significantly lower than the imposed heat stress. This protected the ovaries and possibly the later phase of pollen tube growth from the adverse effects of heat stress. Failure of maize kernel fertilization was observed within 6 h of heat stress exposure postpollination. This was accompanied by a significant restriction of early pollen tube growth rather than pollen germination. Limitations on early pollen tube growth were therefore a major factor contributing to heat stress-induced kernel sterility. Exposure to heat stress altered the sugar composition of silks, suggesting that hexose supply contributed to the limitations on pollen tube growth. Moreover, the activities of sucrose metabolising enzymes, the expression of sucrose degradation and trehalose biosynthesis genes were decreased following heat stress. Significant increases in reactive oxygen species, abscisic acid and auxin levels accompanied by altered expression of phytohormone-related genes may also be important in the heat-induced suppression of pollen tube growth.

Fungal and Toxin Contaminants in Cereal Grains and Flours: Systematic Review and Meta-Analysis

Cereal grains serve as the cornerstone of global nutrition, providing a significant portion of humanity's caloric requirements. However, the presence of fungal genera, such Fusarium, Penicillium, Aspergillus, and Alternaria, known for their mycotoxin-producing abilities, presents a significant threat to human health due to the adverse effects of these toxins. The primary objective of this study was to identify the predominant fungal contaminants in cereal grains utilized in breadmaking, as well as in flour and bread. Moreover, a systematic review, including meta-analysis, was conducted on the occurrence and levels of mycotoxins in wheat flour from the years 2013 to 2023. The genera most frequently reported were Fusarium, followed by Penicillium, Aspergillus, and Alternaria. Among the published reports, the majority focused on the analysis of Deoxynivalenol (DON), which garnered twice as many reports compared to those focusing on Aflatoxins, Zearalenone, and Ochratoxin A. The concentration of these toxins, in most cases determined by HPLC-MS/MS or HPLC coupled with a fluorescence detector (FLD), was occasionally observed to exceed the maximum limits established by national and/or international authorities. The prevalence of mycotoxins in flour samples from the European Union (EU) and China, as well as in foods intended for infants, exhibited a significant reduction compared to other commercial flours assessed by a meta-analysis investigation.

The Triticeae CBF Gene Cluster-To Frost Resistance and Beyond

The pivotal role of CBF/DREB1 transcriptional factors in Triticeae crops involved in the abiotic stress response has been highlighted. The CBFs represent an important hub in the ICE-CBF-COR pathway, which is one of the most relevant mechanisms capable of activating the adaptive response to cold and drought in wheat, barley, and rye. Understanding the intricate mechanisms and regulation of the cluster of CBF genes harbored by the homoeologous chromosome group 5 entails significant potential for the genetic improvement of small grain cereals. Triticeae crops seem to share common mechanisms characterized, however, by some peculiar aspects of the response to stress, highlighting a combined landscape of single-nucleotide variants and copy number variation involving CBF members of subgroup IV. Moreover, while chromosome 5 ploidy appears to confer species-specific levels of resistance, an important involvement of the ICE factor might explain the greater tolerance of rye. By unraveling the genetic basis of abiotic stress tolerance, researchers can develop resilient varieties better equipped to withstand extreme environmental conditions. Hence, advancing our knowledge of CBFs and their interactions represents a promising avenue for improving crop resilience and food security.

Acclimation response and management strategies to combat heat stress in wheat for sustainable agriculture: A state-of-the-art review

Unpredicted variability in climate change on the planet is associated with frequent extreme high-temperature events impacting crop yield globally. Wheat is an economically and nutritionally important crop that fulfils global food requirements and each degree rise in temperature results in ∼6% of its yield reduction. Thus, understanding the impact of climate change, especially the terminal heat stress on global wheat production, becomes critically important for policymakers, crop breeders, researchers and scientists to ensure global food security. This review describes how wheat perceives heat stress and induces stress adaptation events by its morpho-physiological, phenological, molecular, and biochemical makeup. Temperature above a threshold level in crop vicinity leads to irreversible injuries, viz. destruction of cellular membranes and enzymes, generation of active oxygen species, redox imbalance, etc. To cope with these changes, wheat activates its heat tolerance mechanisms characterized by hoarding up soluble carbohydrates, signalling molecules, and heat tolerance gene expressions. Being vulnerable to heat stress, increasing wheat production without delay seeks strategies to mitigate the detrimental effects and provoke the methods for its sustainable development. Thus, to ensure the crop's resilience to stress and increasing food demand, this article circumscribes the integrated management approaches to enhance wheat's performance and adaptive capacity besides its alleviating risks of increasing temperature anticipated with climate change. Implementing these integrated strategies in the face of risks from rising temperatures will assist us in producing sustainable wheat with improved yield.

Sustainable transformation of agriculture requires landscape experiments

Transformation of agriculture to realise sustainable site-specific management requires comprehensive scientific support based on field experiments to capture the complex agroecological process, incite new policies and integrate them into farmers' decisions. However, current experimental approaches are limited in addressing the wide spectrum of sustainable agroecosystem and landscape characteristics and in supplying stakeholders with suitable solutions and measures. This review identifies major constraints in current field experimentation, such as a lack of consideration of multiple processes and scales and a limited ability to address interactions between them. It emphasizes the urgent need to establish a new category of landscape experimentation that empowers agricultural research on sustainable agricultural systems, aiming at elucidating interactions among various landscape structures and functions, encompassing both natural and anthropogenic features. It extensively discusses the key characteristics of landscape experiments and major opportunities to include them in the agricultural research agenda. In particular, simultaneously considering multiple factors, and thus processes at different scales and possible synergies or antagonisms among them would boost our understanding of heterogeneous agricultural landscapes. We also highlight that though various studies identified promising approaches with respect to experimental design and data analysis, further developments are still required to build a fully functional and integrated framework for landscape experimentation in agricultural settings.

Genetic diversity, transcript heterogeneity and allele mining of TaSKP1-6B-4 gene variants across diverse genotypes under terminal heat stress and genome wide characterization of TaSKP1 gene family from bread wheat (Triticum aestivum L.)

SKP1 (S-phase kinase protein1) is an essential regulatory component of SCF (Skp1-cullin-F-box) E3 ubiquitin ligases involved in maintenance of cellular protein homeostasis through ubiquitin mediated proteasome system (UPS). UPS play a key role in stress response and grain yield. Earlier, we isolated TaSKP1-6B-4, highly induced in flag leaf tissues (Accession No. KJ830759.1) of developing wheat caryopses under heat stress. To further assess the functional role of SKP1, genetic variability analysis was carried out in a panel of 25 contrasting germplasm through extensive phenotyping and transcript profiling of TaSKP1-6B-4 during anthesis under ambient and terminal heat stress (THS) in field experiments for two consecutive years. The analysis of variance revealed significant variations for all the traits studied. Higher H2(%), GCV, PCV, GA and GA% mean observed in tiller number per plant (23.81, 17.65, 5.71, 28, 30.86%) and grain number per head (30.27, 82.79, 60.16, 105.00, 108.64%) under THS over ambient temperature. Higher fold induction of TaSKP1-6B-4 transcripts was recorded in 10 genotypes viz. HD2967 (9.9), IC145456 (6.18) in flag leaf; while C-306 (15.88), RAJ3765 (8.37) in ear head. Allele mining of SKP1-6B-4 showed genotypic sequence variations. Whole genome wide search of SKP1 gene family identified 95 SKP1 genes which were structurally characterized. Grain yield, leaf senescence and other agronomic-morpho-physiological parameters combined with transcript profiling, cvHD2967, was found to be the best positively responsive to THS which by pedigree was not heat tolerant. We report a novel 2 year comprehensive field based analysis on collective genetic variability and SKP1/UPS modulation under a natural environmental setting. The data reveals potential functional role of UPS under THS and tolerant cultivars can be further utilized for clarifying the role of UPS mechanistically at the molecular level and for developing terminal heat stress tolerant wheat.

Transgenic strategies to improve the thermotolerance of photosynthesis

Warming driven by the accumulation of greenhouse gases in the atmosphere is irreversible over at least the next century, unless practical technologies are rapidly developed and deployed at scale to remove and sequester carbon dioxide from the atmosphere. Accepting this reality highlights the central importance for crop agriculture to develop adaptation strategies for a warmer future. While nearly all processes in plants are impacted by above optimum temperatures, the impact of heat stress on photosynthetic processes stand out for their centrality. Here, we review transgenic strategies that show promise in improving the high-temperature tolerance of specific subprocesses of photosynthesis and in some cases have already been shown in proof of concept in field experiments to protect yield from high temperature-induced losses. We also highlight other manipulations to photosynthetic processes for which full proof of concept is still lacking but we contend warrant further attention. Warming that has already occurred over the past several decades has had detrimental impacts on crop production in many parts of the world. Declining productivity presages a rapidly developing global crisis in food security particularly in low income countries. Transgenic manipulation of photosynthesis to engineer greater high-temperature resilience holds encouraging promise to help meet this challenge.

Multi-omics atlas of combinatorial abiotic stress responses in wheat

Field-grown crops rarely experience growth conditions in which yield can be maximized. Environmental stresses occur in combination, with advancements in crop tolerance further complicated by its polygenic nature. Strategic targeting of causal genes is required to meet future crop production needs. Here, we employed a systems biology approach in wheat (Triticum aestivum L.) to investigate physio-metabolic adjustments and transcriptome reprogramming involved in acclimations to heat, drought, salinity and all combinations therein. A significant shift in magnitude and complexity of plant response was evident across stress scenarios based on the agronomic losses, increased proline concentrations and 8.7-fold increase in unique differentially expressed transcripts (DETs) observed under the triple stress condition. Transcriptome data from all stress treatments were assembled into an online, open access eFP browser for visualizing gene expression during abiotic stress. Weighted gene co-expression network analysis revealed 152 hub genes of which 32% contained the ethylene-responsive element binding factor-associated amphiphilic repression (EAR) transcriptional repression motif. Cross-referencing against the 31 DETs common to all stress treatments isolated TaWRKY33 as a leading candidate for greater plant tolerance to combinatorial stresses. Integration of our findings with available literature on gene functional characterization allowed us to further suggest flexible gene combinations for future adaptive gene stacking in wheat. Our approach demonstrates the strength of robust multi-omics-based data resources for gene discovery in complex environmental conditions. Accessibility of such datasets will promote cross-validation of candidate genes across studies and aid in accelerating causal gene validation for crop resiliency.

How Antioxidants, Osmoregulation, Genes and Metabolites Regulate the Late Seeding Tolerance of Rapeseeds (Brassica napus L.) during Wintering

Rapeseed seeding dates are largely delayed under the rice-rape rotation system, but how rapeseeds adapt to the delayed environment remains unclear. Here, five seeding dates (20 October, 30 October, 10 November, 20 November and 30 November, T1 to T5) were set and the dynamic differences between two late-seeding-tolerant (LST) and two late-seeding-sensitive (LSS) rapeseed cultivars were investigated in a field experiment. The growth was significantly repressed and the foldchange (LST/LSS) of yield increased from 1.50-T1 to 2.64-T5 with the delay in seeding. Both LST cultivars showed higher plant coverage than the LSS cultivars according to visible/hyperspectral imaging and the vegetation index acquired from an unmanned aerial vehicle. Fluorescence imaging, DAB and NBT staining showed that the LSS cultivars suffered more stress damage than the LST cultivars. Antioxidant enzymes (SOD, POD, CAT, APX) and osmoregulation substances (proline, soluble sugar, soluble protein) were decreased with the delay in seeding, while the LST cultivar levels were higher than those of the LSS cultivars. A comparative analysis of transcriptomes and metabolomes showed that 55 pathways involving 123 differentially expressed genes (DEGs) and 107 differentially accumulated metabolites (DAMs) participated in late seeding tolerance regulation, while 39 pathways involving 60 DEGs and 68 DAMs were related to sensitivity. Levanbiose, α-isopropylmalate, s-ribosyl-L-homocysteine, lauroyl-CoA and argino-succinate were differentially accumulated in both cultivars, while genes including isocitrate dehydrogenase, pyruvate kinase, phosphoenolpyruvate carboxykinase and newgene_7532 were also largely regulated. This study revealed the dynamic regulation mechanisms of rapeseeds on late seeding conditions, which showed considerable potential for the genetic improvement of rapeseed.

Observations and implication of thermal tolerance in the Arabidopsis proteome

Knowledge of the thermal stability of plant proteomes within their native environments would aid in the design of climate-resilient crop plants. Identification of thermo-sensitive and -resilient proteins not only provides foundational understanding of systematic heat-induced damage but also offers insight into protein interactions and protein evolution.

Systematic thermal analysis of the Arabidopsis proteome: Thermal tolerance, organization, and evolution

Understanding the thermal stability of the plant proteome in the context of the native cellular environment would aid the design of crops with high thermal tolerance, but only limited such data are available. Here, we applied quantitative mass spectrometry to profile the thermal stability of the Arabidopsis proteome and identify thermo-sensitive and thermo-resilient protein networks in Arabidopsis, providing a basis for understanding heat-induced damage. We also show that the similarities of the protein-melting curves can be used as a proxy to evaluate system-wide protein-protein interactions in non-engineered plants and enable the identification of transient interactions exhibited by metabolons in the context of the cellular environment. Finally, we report a systematic comparison of the thermal stability of paralogs in Arabidopsis to aid the investigation and understanding of gene duplication and protein evolution. Taken together, our results could have broad implications for the fields of plant thermal tolerance, plant protein assemblies, and evolution.

Genomic characterization and gene bank curation of Aegilops: the wild relatives of wheat

Genetic diversity found in crop wild relatives is critical to preserve and utilize for crop improvement to achieve sustainable food production amid climate change and increased demand. We genetically characterized a large collection of 1,041 Aegilops accessions distributed among 23 different species using more than 45K single nucleotide polymorphisms identified by genotyping-by-sequencing. The Wheat Genetics Resource Center (WGRC) Aegilops germplasm collection was curated through the identification of misclassified and redundant accessions. There were 49 misclassified and 28 sets of redundant accessions within the four diploid species. The curated germplasm sets now have improved utility for genetic studies and wheat improvement. We constructed a phylogenetic tree and principal component analysis cluster for all Aegilops species together, giving one of the most comprehensive views of Aegilops. The Sitopsis section and the U genome Aegilops clade were further scrutinized with in-depth population analysis. The genetic relatedness among the pair of Aegilops species provided strong evidence for the species evolution, speciation, and diversification. We inferred genome symbols for two species Ae. neglecta and Ae. columnaris based on the sequence read mapping and the presence of segregating loci on the pertinent genomes as well as genetic clustering. The high genetic diversity observed among Aegilops species indicated that the genus could play an even greater role in providing the critical need for untapped genetic diversity for future wheat breeding and improvement. To fully characterize these Aegilops species, there is an urgent need to generate reference assemblies for these wild wheats, especially for the polyploid Aegilops.

Nano-Biochar Enhances Wheat Crop Productivity by Vindicating the Effects of Drought: In Relation to Physiological and Phenological Stages

Climatic changes are major hindrances to crop productivity. Likewise, water scarcity is the major obstacle during different physiological and phenological stages, which ultimately reduces the wheat crop yield. So, there is a dire need to adopt modern approaches such as soil amendments, i.e., using nano-biochar (NBC) to boost soil health and wheat crop productivity. Therefore, a case study was performed in the wire house of the Agronomy Department, Faculty of Agriculture and Environmental Sciences, Islamia University of Bahawalpur. CRD (completely randomized design) with four treatments of NBC, i.e., NBC0 (control), NBC1 (0.5%), NBC2 (1.00%), NBC3 (1.5%), and four drought levels D0 = control, D1 = drought at tillering, D2 = drought at flowering, and D3 = drought at grain filling was used. The hypothesis for the case study was to investigate if the NBC increases crop productivity by boosting physiological and chemical attributes under different drought conditions at different phenological stages. Results showed that among NBC treatments, NBC2 (1.00%) showed 37.10% increase in peroxidase activity, 28.60% in superoxide dismutase, 63.33% in catalase, 22.03% in ascorbate peroxidase, and 6.66% in plant height as compared to other NBC treatments, whereas among drought treatments, D0 = control stood out in comparison to water deficit treatments at critical growth and development stages, statistically analyzed data revealed that D0 was able to generate plant height 6.17 times more, 12.76% in the number of grains per spike, 4.60% in osmotic potential, and 2.96% in stomatal conductance activities of wheat crop. D3 and NBC0 were identified as treatment levels with the statistically lowest growth and yield returns, respectively. It showed a decrease of 4.69% in leaf relative water contents, 12.33% in water potential, and 23.64% in fertile tillers. It was recommended that drought is avoided at any critical growth, particularly at the grain-filling stage. The use of organic substances (fertilizers) must be promoted as they possess soil and crop health-promoting properties and also reduce different management expenses (fertilizer cost). Using NBC helps boost crop growth in the presence of a limited water supply. However, extensive research is needed to find out the impact of these organic substances (humic acid, farmyard manure, and NBC) on different crops, particularly on wheat, under stress conditions.

Impact of rising temperatures on historical wheat yield, phenology, and grain size in Catalonia

Introduction

Climate change poses significant challenges to agriculture, impacting crop yields and necessitating adaptive strategies in breeding programs. This study investigates the genetic yield progress of wheat varieties in Catalonia, Spain, from 2007 to 2021, and examines the relationship between genetic yield and climate-related factors, such as temperature. Understanding these dynamics is crucial for ensuring the resilience of wheat crops in the face of changing environmental conditions.

Methods

Genetic yield progress was assessed using a linear regression function, comparing the average yield changes of newly released wheat varieties to benchmark varieties. Additionally, a quadratic function was employed to model genetic yield progress in winter wheat (WW). The study also analyzed correlations between genetic yield (GY) and normalized values of hectoliter weight (HLW) and the number of grains (NG) for both spring wheat (SW) and WW. Weather data were used to confirm climate change impacts on temperature and its effects on wheat growth and development.

Results

The study found that genetic yield was stagnant for SW but increased linearly by 1.31% per year for WW. However, the quadratic function indicated a possible plateau in WW genetic yield progress in recent years. Positive correlations were observed between GY and normalized values of HLW and NG for both SW and WW. Climate change was evident in Catalonia, with temperatures increasing at a rate of 0.050 °C per year. This rise in temperature had detrimental effects on days to heading (DH) and HLW, with reductions observed in both SW and WW for each °C increase in annual minimum and average temperature.

Discussion

The findings highlighted the urgent need to address the impact of climate change on wheat cultivation. The stagnation of genetic yield in SW and the potential plateau in WW genetic yield progress call for adaptive measures. Breeding programs should prioritize phenological adjustments, particularly sowing date optimization, to align with the most favorable months of the year. Moreover, efforts should be made to enhance HLW and the number of grains per unit area in new wheat varieties to counteract the negative effects of rising temperatures. This research underscores the importance of ongoing monitoring and adaptation in agricultural practices to ensure yield resilience in the context of a changing climate.

Frost Damage Index: The Antipode of Growing Degree Days

Abiotic stresses such as heat and frost limit plant growth and productivity. Image-based field phenotyping methods allow quantifying not only plant growth but also plant senescence. Winter crops show senescence caused by cold spells, visible as declines in leaf area. We accurately quantified such declines by monitoring changes in canopy cover based on time-resolved high-resolution imagery in the field. Thirty-six winter wheat genotypes were measured in multiple years. A concept termed "frost damage index" (FDI) was developed that, in analogy to growing degree days, summarizes frost events in a cumulative way. The measured sensitivity of genotypes to the FDI correlated with visual scorings commonly used in breeding to assess winter hardiness. The FDI concept could be adapted to other factors such as drought or heat stress. While commonly not considered in plant growth modeling, integrating such degradation processes may be key to improving the prediction of plant performance for future climate scenarios.

Ethiopia's wheat production pathways to self-sufficiency through land area expansion, irrigation advance, and yield gap closure

Ethiopia is the second largest wheat producer in Africa. Though wheat production has been increasing steadily in the past decades, the demand for the crop outstripped domestic supply and forced the country to cover about 30 % of the deficit through commercial imports and food aid. The utilization of wheat is rising at 9 % annually while the production is increasing at 7.8 %, showing a continued widening between consumption and production. With a growing demand due to bourgeoning population, increase in income, and preference toward wheat-based products, the country has a long journey to achieve wheat self-sufficiency and save the scarce foreign currency reserve spent on import. The government of Ethiopia is committed to self-sufficiency through initiatives such as wheat area expansion, irrigation development and yield gap closure. In this review, we explored wheat production trends and the roles of the recent government initiatives toward wheat self-sufficiency. The review indicated that wheat production and productivity have increased in Ethiopia, but the wheat self-sufficiency of the country has declined from 99 % in the 1960s to 70 % at present. The future land area expansion in traditionally wheat-producing areas is limited, and wheat land suitability and yield potential is likely to reduce under climate change. Thus, the options to transform the wheat sector while reducing greenhouse gas emissions is through yield gap closure through intensification on existing cropland and judicious temporal and spatial expansion of irrigated wheat areas. The yield gap closure requires higher and more efficient input supply and utilization, investments in modern technologies, as well as supportive agricultural policies. To improve the productivity of small landholder farmers and increase intensity of production through irrigation investment on irrigation structures and facilities is required. Finally, we recommend further studies on yield gap analysis, the role of government initiatives, and wheat land suitability under current and future climate change scenarios at the local level.

Adapting crop production to climate change and air pollution at different scales

Air pollution and climate change are tightly interconnected and jointly affect field crop production and agroecosystem health. Although our understanding of the individual and combined impacts of air pollution and climate change factors is improving, the adaptation of crop production to concurrent air pollution and climate change remains challenging to resolve. Here we evaluate recent advances in the adaptation of crop production to climate change and air pollution at the plant, field and ecosystem scales. The main approaches at the plant level include the integration of genetic variation, molecular breeding and phenotyping. Field-level techniques include optimizing cultivation practices, promoting mixed cropping and diversification, and applying technologies such as antiozonants, nanotechnology and robot-assisted farming. Plant- and field-level techniques would be further facilitated by enhancing soil resilience, incorporating precision agriculture and modifying the hydrology and microclimate of agricultural landscapes at the ecosystem level. Strategies and opportunities for crop production under climate change and air pollution are discussed.

Machine learning in photosynthesis: Prospects on sustainable crop development

Improving photosynthesis is a promising avenue to increase food security. Studying photosynthetic traits with the aim to improve efficiency has been one of many strategies to increase crop yield but analyzing large data sets presents an ongoing challenge. Machine learning (ML) represents a ubiquitous tool that can provide a more elaborate data analysis. Here we review the application of ML in various domains of photosynthetic research, as well as in photosynthetic pigment studies. We highlight how correlating hyperspectral data with photosynthetic parameters to improve crop yield could be achieved through various ML algorithms. We also propose strategies to employ ML in promoting photosynthetic pigment research for furthering crop yield.

Characterization of the skill of the CORDEX-Africa regional climate models to simulate regional climate setting in the East African Transboundary Omo Gibe River Basin, Ethiopia

Regional climate models (RCMs) that produce good outputs in one region or for specific variables may underperform for others. Thereby, assessing the performance of various model simulations and their corresponding mean ensemble is critical in identifying the most suitable models. In this regard, a study was conducted to evaluate the performance of ten RCMs against observations from multiple ground-based stations in the East African Transboundary Omo Gibe River Basin, Ethiopia, during the baseline period of 1986-2005. The study evaluated the models' ability to replicate various aspects of climatic variables and their corresponding statistical indicators. The results confirmed that RCMs have varying abilities to reproduce climatic conditions across the basin. The ensembles and RACMO22T (EC-EARTH) were better at replicating the average annual precipitation distribution. Meanwhile, the CCLM4-8-17 (MPI) together with the ensembles better captured the measured precipitation annually, despite the discrepancies in the actual magnitudes. All RCMs were able to simulate the seasonal precipitation patterns effectively, with RACMO22T (EC-EARTH), CCLM4-8-17 (CNRM), RCA4 (CNRM), CCLM4-8-17 (MPI), and REMO2009 (MPI) models captured superior, excluding the maximum value. Interannual and seasonal rainfall pattern variations were more significant than variations in air temperature. Additionally, a better correlation was observed between actual and simulated precipitation at multiple separate monitoring places. The RCA4 (MPI) and CCLM4-8-17 (MPI) demonstrated reasonable minimum and maximum temperatures. The RCA4 (MIROC5) model was more effective in reproducing extreme precipitation events. However, all RCMs and their ensembles tended to overestimate the return periods of these events. In general, the research highlights the importance of selecting reliable RCMs that better replicate observed climatic settings and employing the ensemble mean of top-performing models following systematic bias adjustment for a specific application.

Alternative splicing of TaHSFA6e modulates heat shock protein-mediated translational regulation in response to heat stress in wheat

Heat stress greatly threatens crop production. Plants have evolved multiple adaptive mechanisms, including alternative splicing, that allow them to withstand this stress. However, how alternative splicing contributes to heat stress responses in wheat (Triticum aestivum) is unclear. We reveal that the heat shock transcription factor gene TaHSFA6e is alternatively spliced in response to heat stress. TaHSFA6e generates two major functional transcripts: TaHSFA6e-II and TaHSFA6e-III. TaHSFA6e-III enhances the transcriptional activity of three downstream heat shock protein 70 (TaHSP70) genes to a greater extent than does TaHSFA6e-II. Further investigation reveals that the enhanced transcriptional activity of TaHSFA6e-III is due to a 14-amino acid peptide at its C-terminus, which arises from alternative splicing and is predicted to form an amphipathic helix. Results show that knockout of TaHSFA6e or TaHSP70s increases heat sensitivity in wheat. Moreover, TaHSP70s are localized in stress granule following exposure to heat stress and are involved in regulating stress granule disassembly and translation re-initiation upon stress relief. Polysome profiling analysis confirms that the translational efficiency of stress granule stored mRNAs is lower at the recovery stage in Tahsp70s mutants than in the wild types. Our finding provides insight into the molecular mechanisms by which alternative splicing improves the thermotolerance in wheat.

Identification of Climate-Smart Bread Wheat Germplasm Lines with Enhanced Adaptation to Global Warming

Bread wheat (Triticum aestivum L.) is widely grown in sub-tropical and tropical areas and, as such, it is exposed to heatstress especially during the grain filling period (GFP). Global warming has further affected its production and productivity in these heat-stressed environments. We examined the effects of heatstress on 18 morpho-physiological and yield-related traits in 96 bread wheat accessions. Heat stress decreased crop growth and GFP, and consequently reduced morphological and yield-related traits in the delayed sown crop. A low heat susceptibility index and high yield stability were used for selecting tolerant accessions. Under heatstress, the days to 50% anthesis, flag-leaf area, chlorophyll content, normalized difference vegetation index (NDVI), thousand grain weight (TGW), harvest index and grain yield were significantly reduced both in tolerant and susceptible accessions. The reduction was severe in susceptible accessions (48.2% grain yield reduction in IC277741). The plant height, peduncle length and spike length showeda significant reduction in susceptible accessions, but a non-significant reduction in the tolerant accessions under the heatstress. The physiological traits like the canopy temperature depression (CTD), plant waxiness and leaf rolling were increased in tolerant accessions under heatstress. Scanning electron microscopy of matured wheat grains revealed ultrastructural changes in endosperm and aleurone cells due to heat stress. The reduction in size and density of large starch granules is the major cause of the yield and TGW decrease in the heat-stress-susceptible accessions. The most stable and high-yielding accessions, namely, IC566223, IC128454, IC335792, EC576707, IC535176, IC529207, IC446713 and IC416019 were identified as the climate-smart germplasm lines. We selected germplasm lines possessing desirable traits as potential parents for the development of bi-parent and multi-parent mapping populations.

Temperature perception by plants

Plants constantly face fluctuating ambient temperatures and must adapt to survive under stressful conditions. Temperature affects many aspects of plant growth and development through a complex network of transcriptional responses. Although temperature sensing is a crucial primary step in initiating transcriptional responses via Ca2+ and/or reactive oxygen species signaling, an understanding of how plants perceive temperature has remained elusive. However, recent studies have yielded breakthroughs in our understanding of temperature sensors and thermosensation mechanisms. We review recent findings on potential temperature sensors and emerging thermosensation mechanisms, including biomolecular condensate formation through phase separation in plants. We also compare the temperature perception mechanisms of plants with those of other organisms to provide insights into understanding temperature sensing by plants.

GWAS for Early-Establishment QTLs and Their Linkage to Major Phenology-Affecting Genes (Vrn, Ppd, and Eps) in Bread Wheat

Farmers in northern and central Indian regions prefer to plant wheat early in the season to take advantage of the remaining soil moisture. By planting crops before the start of the season, it is possible to extend the time frame for spring wheat. The early-wheat-establishment experiment began in the 2017 growing season at the Borlaug Institute for South Asia (BISA) in Ludhiana, India, and, after three years of intensive study, numerous agronomic, physiological, and yield data points were gathered. This study aimed to identify wheat lines suitable for early establishment through an analysis of the agro-morphological traits and the genetic mapping of associated genes or quantitative trait loci (QTLs). Advancing the planting schedule by two-three weeks proved to be advantageous in terms of providing a longer duration for crop growth and reducing the need for irrigation. This is attributed to the presence of residual soil moisture resulting from the monsoon season. Early sowing facilitated the selection of genotypes able to withstand early elevated temperatures and a prolonged phenological period. The ideotype, which includes increased photo-growing degree days for booting and heading, as well as a longer grain-filling period, is better suited to early planting than timely planting. Senescence was delayed in combination with a slower rate of canopy temperature rise, which was an excellent trait for early-adapted ideotypes. Thus, a novel approach to wheat breeding would include a screening of genotypes for early planting and an ideotype design with consistent and appropriate features. A genome-wide association study (GWAS) revealed multiple QTLs linked to early adaptation in terms of the yield and its contributing traits. Among them, 44 novel QTLs were also found along with known loci. Furthermore, the study discovered that the phenology regulatory genes, such as Vrn and Ppd, are in the same genomic region, thereby contributing to early adaptation.

Response of Wheat, Maize, and Rice to Changes in Temperature, Precipitation, CO2 Concentration, and Uncertainty Based on Crop Simulation Approaches

The influence of global climate change on agricultural productivity is an essential issue of ongoing concern. The growth and development of wheat, maize, and rice are influenced by elevated atmospheric CO₂ concentrations, increased temperatures, and seasonal rainfall patterns. However, due to differences in research methodologies (e.g., crop models, climate models, and climate scenarios), there is uncertainty in the existing studies regarding the magnitude and direction of future climate change impacts on crop yields. In order to completely assess the possible consequences of climate change and adaptation measures on crop production and to analyze the associated uncertainties, a database of future crop yield changes was developed using 68 published studies (including 1842 samples). A local polynomial approach was used with the full dataset to investigate the response of crop yield changes to variations in maximum and minimum temperatures, mean temperature, precipitation, and CO₂ concentrations. Then, a linear mixed-effects regression model was utilized with the limited dataset to explore the quantitative relationships between them. It was found that maximum temperature, precipitation, adaptation measure, study area, and climate model had significant effects on changes in crop yield. Crop yield will decline by 4.21% for each 1 °C rise in maximum temperature and increase by 0.43% for each 1% rise in precipitation. While higher CO₂ concentrations and suitable management strategies could mitigate the negative effects of warming temperatures, crop yield with adaptation measures increased by 64.09% compared to crop yield without adaptation measures. Moreover, the uncertainty of simulations can be decreased by using numerous climate models. The results may be utilized to guide policy regarding the influence of climate change and to promote the creation of adaptation plans that will increase crop systems' resilience in the future.

Short- and long-term warming events on photosynthetic physiology, growth, and yields of field grown crops

Global temperatures are rising from increasing concentrations of greenhouse gases in the atmosphere associated with anthropogenic activities. Global warming includes a warmer shift in mean temperatures as well as increases in the probability of extreme heating events, termed heat waves. Despite the ability of plants to cope with temporal variations in temperature, global warming is increasingly presenting challenges to agroecosystems. The impact of warming on crop species has direct consequences on food security, therefore understanding impacts and opportunities to adapt crops to global warming necessitates experimentation that allows for modification of growth environments to represent global warming scenarios. Published studies addressing crop responses to warming are extensive, however, in-field studies where growth temperature is manipulated to mimic global warming are limited. Here, we provide an overview of in-field heating techniques employed to understand crop responses to warmer growth environments. We then focus on key results associated with season-long warming, as expected with rising global mean temperatures, and with heat waves, as a consequence of increasing temperature variability and rising global mean temperatures. We then discuss the role of rising temperatures on atmospheric water vapor pressure deficit and potential implications for crop photosynthesis and productivity. Finally, we review strategies by which crop photosynthetic processes might be optimized to adapt crops to the increasing temperatures and frequencies of heat waves. Key findings from this review are that higher temperatures consistently reduce photosynthesis and yields of crops even as atmospheric carbon dioxide increases, yet potential strategies to minimize losses from high-temperature exist.