Strategies for utilization of crop wild relatives in plant breeding programs

Cotton under heat stress: a comprehensive review of molecular breeding, genomics, and multi-omics strategies

Cotton is a vital fiber crop for the global textile industry, but rising temperatures due to climate change threaten its growth, fiber quality and yields. Heat stress disrupts key physiological and biochemical processes, affecting carbohydrate metabolism, hormone signaling, calcium and gene regulation and expression. This review article explores cotton's defense mechanism against heat stress, including epigenetic regulations and transgenic approaches, with a focus on genome editing tools. Given the limitations of traditional breeding, advanced omics technologies such as GWAS, transcriptomics, proteomics, ionomics, metabolomics, phenomics and CRISPR-Cas9 offer promising solutions for developing heat-resistant cotton varieties. This review highlights the need for innovative strategies to ensure sustainable cotton production under climate change.

Crop Wild Relatives (CWRs) in the United Arab Emirates: Resources for Climate Resilience and Their Potential Medicinal Applications

Global climate change threatens the production, growth, and sustainability of plants. Crop wild relatives (CWRs) offer a practical and sustainable solution to these climatic issues by boosting genetic diversity and crop resilience. Even though CWRs are wild relatives of domesticated plants, they are nevertheless mostly neglected. This review focuses on the possible application of CWRs, which are found in the United Arab Emirates (UAE) and are known for their abiotic stress tolerance and potential medicinal properties. In olden days, traditionally, CWRs has been used as medicine for various ailments as they are rich in phytochemical compounds. However, the medicinal potential of these wild plant species is decreasing at an alarming rate due to climate change stress factors. The medicinal potential of these native crop wild plant species must be investigated because they could be a useful asset in the healthcare sector. Research on pangenomics studies of certain CWRs is also highlighted in the review, which reveals genetic variability caused due to climate change stress factors and how these genetic variability changes affect the production of secondary metabolites that have potent medicinal value. This provides insights into developing personalized medicine, in which particular CWRs plant species can be chosen or modified to generate medicinal compounds. Despite their superior medicinal properties, many CWRs in the UAE are still not well understood. Finding the desired genes coding for the biosynthesis of specific phytochemicals or secondary metabolites may help us better understand how these substances are synthesized and how to increase their production for a range of treatments.

Genetic structure and designing a preliminary core collection of Zizania latifolia in China based on 12 microsatellites markers

The genetic diversity and structure of wild crop relatives are crucial for their conservation and utilization in breeding programs. This study presents a comprehensive survey and collection of Zizania latifolia across its natural distribution range in China. Using 12 microsatellite markers, the genetic diversity of 357 wild Z. latifolia accessions from 25 populations was evaluated, revealing a high genetic diversity (H e = 0.439). The genetic structure analysis indicated significant genetic differentiation among populations, with evidence of isolation by distance. CoreHunter3 and PowerMarker software were employed to design a preliminary core collection, and the final core collection comprised 92 wild accessions. The core collection was found to be representative of the original germplasm, ensuring the effective conservation of Z. latifolia's genetic resources. This study would provide valuable insights for the development of conservation strategies and the utilization of Z. latifolia.

Development and characterization of small translocations between the Pm13 introgression from Aegilops longissima and wheat homoeologous A, B and D chromosomes

BACKGROUND

Wild relatives have substantial impacts on the resistance of wheat to biotic and abiotic stresses. The genetic diversity of these wild varieties can be employed to widen the wheat gene pool by introducing wild allele introgression and genome structure variations. The powdery mildew resistance gene Pm13 was derived from the wheat wild relative species Aegilops longissima (S1S1, 2n = 2x = 14) and was transferred into wheat chromosome 3BS over 30 years. Until recently, it has not been widely used in wheat breeding, possibly because of the linkage drag associated with Pm13 introgression or poor alien segment compensation to 3BS.

RESULTS

In this study, translocations between the Pm13 introgression and wheat homoeologous A, B and D chromosomes were developed by using a wheat ph1b mutant. The 3Sl (3B) substitution line was hybridized with the CS nullisomic-tetrasomic line N3AT3B, and then F1 was hybridized with the CSph1b mutant. Individuals homozygous for the ph1b mutant carrying the alien chromosome 3Sl were identified from the segregating populations via molecular markers and cytological analysis. Whole-arm recombinant translocations T3SlS.3AL and T3SlS.3BL and small recombinant translocations T3SlS-3AS.3AL, T3SlS-3BS.3BL and T3DS-3SlS-3DS.3DL carrying Pm13 introgression were subsequently identified via molecular cytological analysis. Furthermore, 4 disomic T3SlS-3BS.3BL recombinants carrying the homozygous Pm13 introgression were identified. All the translocations were nearly immune to powdery mildew.

CONCLUSIONS

Our results provide novel alien homoeologous Pm13 translocations for improving powdery mildew resistance in wheat and insights into the interactions between different wheat genomes and alien chromosome segments.

Development and characterization of a complete set of monosomic alien addition lines from Raphanus sativus in Brassica oleracea

KEY MESSAGE

A complete set of monosomic alien addition lines of Radish-Brassica oleracea exhibiting extensive variations was generated and well characterized for their chromosome behaviors and phenotypic characteristics. Monosomic alien addition lines (MAALs) are developed through interspecific hybridization, where an alien chromosome from a relative species is introduced into the genome of the recipient plant, serving as valuable genetic resources. In this study, an allotetraploid Raphanobrassica (RRCC, 2n = 36) was created from the interspecific hybridization between radish (Raphanus sativus, RR, 2n = 18) and Brassica oleracea (CC, 2n = 18). Subsequently, this Raphanobrassica was repeatedly backcrossed with radish to generate an aneuploid population. The identification of a complete set of MAALs (RR + 1C1-9, 2n = 19) was achieved using PCR with C chromosome-specific markers and fluorescence in situ hybridization, revealing extensive morphological variations, particularly in the shape and size of the fleshy root. A complete set of MAALs was achieved with only one chromosome from 1 to 9 linkage groups of the C genome. Compared with parental radish, most of the MAALs showed a noticeable delay in root swelling, particularly the RR-C6 that did not exhibit obvious root swelling throughout its entire growth stage. Cytological analysis indicated that the MAAL lines containing chromosome C8 exhibited the highest frequency of intergenomic chromosome pairings. Additionally, some introgressive radish lines derived from MAALs displayed a preference toward the donor B. oleracea or over-parent heterosis for some certain nutritional components. Overall, these MAALs serve as valuable germplasm for the genetic enhancement of radish and provide insights into the interactions between the R genome and C chromosomes.

Wild soybean cotyledons at the emergence stage tolerate alkali stress by maintaining carbon and nitrogen metabolism, and accumulating organic acids

Soil alkalization is a global ecological problem that constrains food security and sustainable socio-economic development. As a wild relative of soybean, wild soybean (Glycine soja) exhibits strong salt and alkali stress resistance and its cotyledons play a key role during the emergence (VE) stage. This study aimed to compare variations in growth parameters, cotyledon ultrastructure, photosynthetic physiology, mineral ion and metabolite contents, and gene expression in two ecotypes of wild soybean to elucidate the regulatory mechanisms underlying alkali stress resistance in salt-tolerant wild soybean cotyledons during the VE stage. The results showed that salt-tolerant wild soybean cotyledons exhibited relatively stable growth parameters, dense and orderly chloroplast structure, high photosynthetic rates, as well as high K+ and Ca2+ contents under alkali stress. Metabolomics, transcriptomics, and weighted gene co-expression network analyses revealed that salt-tolerant wild soybean cotyledons adapted to alkali stress during the VE stage by enhancing photosynthetic carbon assimilation pathways, increasing methionine and proline biosynthesis, and enhancing gamma-aminobutyric acid biosynthesis, thereby maintaining a stable carbon and nitrogen balance. In addition, upregulation of the expression of ICL, MS, and ACO2 led to the accumulation of various organic acids, such as pyruvic, aconitic, succinic, oxalic, malic, and fumaric acids, thereby promoting the synthesis of organic acid metabolism modules. This study provides novel insights into the key metabolic modules by which wild soybeans resist alkali stress.

Construction of a physical map for Aegilops geniculata chromosome 7Mg and localization of its novel purple coleoptile gene

KEY MESSAGE

A physical map of Aegilops geniculata chromosome 7Mg was constructed, and a novel purple coleoptile gene was localized at 7MgS bin FL 0.60-0.65 by development of wheat-Ae. geniculata structural aberrations. The development of wheat-wild relative chromosomal structure aberrations not only provides novel germplasm resources for wheat improvement, but also aids in mapping desirable genes to specific chromosomal regions. Aegilops geniculata (2n = 4x = 28, UgUgMgMg), a wild relative of common wheat, possesses many favorable genes. In this study, Ae. geniculata chromosome 7Mg was identified as harboring a purple coleoptile gene by phenotypic evaluation of Chinese Spring (CS)-Ae. geniculata addition and substitution lines. To construct a physical map of chromosome 7Mg and localize the purple coleoptile gene, 59 molecular markers specific to 7Mg were developed, and 43 wheat-Ae. geniculata 7Mg chromosome structure aberrations were generated based on chromosome centromeric breakage-fusion and ph1b-induced homoeologous recombination. Segment sizes and breakpoint positions of each 7Mg structure aberration were further characterized using in situ hybridization and molecular marker analysis. Consequently, a physical map of chromosome 7Mg was constructed with 59 molecular markers, comprising six bins with 28 markers on 7MgS and six bins with 31 markers on 7MgL, and the purple coleoptile gene was mapped to an interval of FL 0.60-0.65 on 7MgS. The newly developed wheat-Ae. geniculata 7Mg structural aberrations and the physical map of 7Mg will facilitate the transfer and utilization of desirable genes from 7Mg in the future.

Genetic Foundation of Leaf Senescence: Insights from Natural and Cultivated Plant Diversity

Leaf senescence, the final stage of leaf development, is crucial for plant fitness as it enhances nutrient reutilization, supporting reproductive success and overall plant adaptation. Understanding its molecular and genetic regulation is essential to improve crop resilience and productivity, particularly in the face of global climate change. This review explores the significant contributions of natural genetic diversity to our understanding of leaf senescence, focusing on insights from model plants and major crops. We discuss the physiological and adaptive significance of senescence in plant development, environmental adaptation, and agricultural productivity. The review emphasizes the importance of natural genetic variation, including studies on natural accessions, landraces, cultivars, and artificial recombinant lines to unravel the genetic basis of senescence. Various approaches, from quantitative trait loci mapping to genome-wide association analysis and in planta functional analysis, have advanced our knowledge of senescence regulation. Current studies focusing on key regulatory genes and pathways underlying natural senescence, identified from natural or recombinant accession and cultivar populations, are highlighted. We also address the adaptive implications of abiotic and biotic stress factors triggering senescence and the genetic mechanisms underlying these responses. Finally, we discuss the challenges in translating these genetic insights into crop improvement. We propose future research directions, such as expanding studies on under-researched crops, investigating multiple stress combinations, and utilizing advanced technologies, including multiomics and gene editing, to harness natural genetic diversity for crop resilience.

Enhancing aphid resistance in horticultural crops: a breeding prospective

Increasing agricultural losses caused by insect infestations are a significant problem, so it is important to generate pest-resistant crop varieties to address this issue. Several reviews have examined aphid-plant interactions from an entomological perspective. However, few have specifically focused on plant resistance mechanisms to aphids and their applications in breeding for aphid resistance. In this review, we first outline the types of resistance to aphids in plants, namely antixenosis, tolerance (cell wall lignification, resistance proteins), and antibiosis, and we discuss strategies based on each of these resistance mechanisms to generate plant varieties with improved resistance. We then outline research on the complex interactions amongst plants, viruses, and aphids, and discuss how aspects of these interactions can be exploited to improve aphid resistance. A deeper understanding of the epigenetic mechanisms related to induced resistance, i.e. the phenomenon where plants become more resistant to a stress they have encountered previously, may allow for its exploitation in breeding for aphid resistance. Wild relatives of crop plants serve as important sources of resistance traits. Genes related to these traits can be introduced into cultivated crop varieties by breeding or genetic modification, and de novo domestication of wild varieties can be used to exploit multiple excellent characteristics, including aphid resistance. Finally, we discuss the use of molecular design breeding, genomic data, and gene editing to generate new aphid-resistant, high-quality crop varieties.

Growing on calcareous soils and facing climate change

Soil calcium carbonate (CaCO3) impacts plant mineral nutrition far beyond Fe metabolism, imposing constraints for crop growth and quality in calcareous agrosystems. Our knowledge on plant strategies to tolerate CaCO3 effects mainly refers to Fe acquisition. This review provides an update on plant cellular and molecular mechanisms recently described to counteract the negative effects of CaCO3 in soils, as well as recent efforts to identify genetic bases involved in CaCO3 tolerance from natural populations, that could be exploited to breed CaCO3-tolerant crops. Finally, we review the impact of environmental factors (soil water content, air CO2, and temperature) affecting soil CaCO3 equilibrium and plant tolerance to calcareous soils, and we propose strategies for improvement in the context of climate change.

Unlocking diversity from wild relatives of perennial fruit crops in the pan-genomics era

Crop wild relatives of perennial fruit crops have a wealth of untapped genetic diversity that can be utilized for cultivar development. However, barriers such as linkage drag, long juvenility, and high heterozygosity have hindered their utilization. Advancements in genome sequencing technologies and assembly methods, combined with the integration of chromosome conformation capture have made it possible to construct high-quality reference genomes. These genome assemblies can be combined into pan-genomes, capturing inter- and intraspecific variations across coding and non-coding regions. Pan-genomes of perennial fruit crops are being developed to identify the genetic basis of traits. This will help overcome breeding challenges, enabling faster and more targeted development of new cultivars with novel traits through breeding and biotechnology.

Harnessing Multi-Omics Strategies and Bioinformatics Innovations for Advancing Soybean Improvement: A Comprehensive Review

Soybean improvement has entered a new era with the advent of multi-omics strategies and bioinformatics innovations, enabling more precise and efficient breeding practices. This comprehensive review examines the application of multi-omics approaches in soybean-encompassing genomics, transcriptomics, proteomics, metabolomics, epigenomics, and phenomics. We first explore pre-breeding and genomic selection as tools that have laid the groundwork for advanced trait improvement. Subsequently, we dig into the specific contributions of each -omics field, highlighting how bioinformatics tools and resources have facilitated the generation and integration of multifaceted data. The review emphasizes the power of integrating multi-omics datasets to elucidate complex traits and drive the development of superior soybean cultivars. Emerging trends, including novel computational techniques and high-throughput technologies, are discussed in the context of their potential to revolutionize soybean breeding. Finally, we address the challenges associated with multi-omics integration and propose future directions to overcome these hurdles, aiming to accelerate the pace of soybean improvement. This review serves as a crucial resource for researchers and breeders seeking to leverage multi-omics strategies for enhanced soybean productivity and resilience.

Wheat powdery mildew resistance gene Pm13 encodes a mixed lineage kinase domain-like protein

Wheat powdery mildew is one of the most destructive diseases threatening global wheat production. The wild relatives of wheat constitute rich sources of diversity for powdery mildew resistance. Here, we report the map-based cloning of the powdery mildew resistance gene Pm13 from the wild wheat species Aegilops longissima. Pm13 encodes a mixed lineage kinase domain-like (MLKL) protein that contains an N-terminal-domain of MLKL (MLKL_NTD) domain in its N-terminus and a C-terminal serine/threonine kinase (STK) domain. The resistance function of Pm13 is validated by mutagenesis, gene silencing, transgenic assay, and allelic association analyses. The development of introgression lines with significantly reduced chromosome segments of Ae. longissima encompassing Pm13 enables widespread deployment of this gene into wheat cultivars. The cloning of Pm13 may provide valuable insights into the molecular mechanisms underlying Pm13-mediated powdery mildew resistance and highlight the important roles of kinase fusion proteins (KFPs) in wheat immunity.

Strategies for breeding crops for future environments

The green revolution successfully increased agricultural output in the early 1960s by relying primarily on three pillars: plant breeding, irrigation, and chemical fertilization. Today, the need to reduce the use of chemical fertilizers, water scarcity, and future environmental changes, together with a growing population, requires innovative strategies to adapt to a new context and prevent food shortages. Therefore, scientists from around the world are directing their efforts to breed crops for future environments to sustainably produce more nutritious food. Herein, we propose scientific avenues to be reinforced in selecting varieties, including crop wild relatives, either for monoculture or mixed cropping systems, taking advantage of plant-microbial interactions, while considering the diversity of organisms associated with crops and unlocking combinatorial nutritional stresses.

Genome-wide identification of bHLH transcription factors and expression analysis under drought stress in Pseudoroegneria libanotica at germination

The basic helix-loop-helix (bHLH) transcription factor family is the second largest in plants. bHLH transcription factor is not only universally involved in plant growth and metabolism, including photomorphogenesis, light signal transduction, and secondary metabolism, but also plays an important role in plant response to stress. However, the function of bHLH TFs in Pseudoroegneria species has not been studied yet. Pseudoroegneria (Nevski) Á. Löve is a perennial genus of the Triticeae. Pseudoroegneria species are mostly distributed in arid/semi-arid areas and they show good drought tolerance. In this study, we identified 152 PlbHLH TFs in Pseudoroegneria libanotica, which could be classified into 15 groups. Collinearity analysis indicates that 122 PlbHLH genes share homology with wbHLH genes in wheat, and it has lower homology with AtbHLH genes in Arabidopsis. Based on transcriptome profiling under an experiment with three PEG concentrations (0%, 10%, and 20%), 10 up-regulated genes and 11 down-regulated PlbHLH genes were screened. Among them, PlbHLH6, PlbHLH55 and PlbHLH64 as candidate genes may be the key genes related to drought tolerance response at germination, and they have been demonstrated to respond to drought, salt, oxidative, heat, and heavy metal stress in yeast. This study lays the foundation for an in-depth study of the biological roles of PlbHLHs in Pse. libanotica, and discovered new drought-tolerance candidate genes to enhance the genetic background of Triticeae crops.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-024-01433-w.

A platform for whole-genome speed introgression from Aegilops tauschii to wheat for breeding future crops

Breeding new and sustainable crop cultivars of high yields and desirable traits has been a major challenge for ensuring food security for the growing global human population. For polyploid crops such as wheat, introducing genetic variation from wild relatives of its subgenomes is a key strategy to improve the quality of their breeding pools. Over the past decades, considerable progress has been made in speed breeding, genome sequencing, high-throughput phenotyping and genomics-assisted breeding, which now allows us to realize whole-genome introgression from wild relatives to modern crops. Here, we present a standardized protocol to rapidly introgress the entire genome of Aegilops tauschii, the progenitor of the D subgenome of bread wheat, into elite wheat backgrounds. This protocol integrates multiple modern high-throughput technologies and includes three major phases: development of synthetic octaploid wheat, generation of hexaploid A. tauschii-wheat introgression lines (A-WIs) and homozygosis of the generated A-WIs. Our approach readily generates stable introgression lines in 2 y, thus greatly accelerating the generation of A-WIs and the introduction of desirable genes from A. tauschii to wheat cultivars. These A-WIs are valuable for wheat-breeding programs and functional gene discovery. The current protocol can be easily modified and used for introgressing the genomes of wild relatives to other polyploid crops.

Origin, evolution, and diversification of the wall-associated kinase gene family in plants

KEY MESSAGE

The study of the origin, evolution, and diversification of the wall-associated kinase gene family in plants facilitates their functional investigations in the future. Wall-associated kinases (WAKs) make up one subfamily of receptor-like kinases (RLKs), and function directly in plant cell elongation and responses to biotic and abiotic stresses. The biological functions of WAKs have been extensively characterized in angiosperms; however, the origin and evolutionary history of the WAK family in green plants remain unclear. Here, we performed a comprehensive analysis of the WAK family to reveal its origin, evolution, and diversification in green plants. In total, 1061 WAK genes were identified in 37 species from unicellular algae to multicellular plants, and the results showed that WAK genes probably originated before bryophyte differentiation and were widely distributed in land plants, especially angiosperms. The phylogeny indicated that the land plant WAKs gave rise to five clades and underwent lineage-specific expansion after species differentiation. Cis-acting elements and expression patterns analyses of WAK genes in Arabidopsis and rice demonstrated the functional diversity of WAK genes in these two species. Many gene gains and losses have occurred in angiosperms, leading to an increase in the number of gene copies. The evolutionary trajectory of the WAK family during polyploidization was uncovered using Gossypium species. Our results provide insights into the evolution of WAK genes in green plants, facilitating their functional investigations in the future.

Utilization of crop wild relatives for biotic and abiotic stress management in Indian mustard [Brassica juncea (L.) Czern. & Coss.]

Brassica juncea (L.) Czern. & Coss. (Indian mustard) is an economically important edible oil crop. Over the years, plant breeders have developed many elite varieties of B. juncea with better yield traits, but research work on the introgression of stress resilience traits has largely been lagging due to scarcity of resistant donors. Crop wild relatives (CWRs) are the weedy relatives of domesticated plant species which are left unutilized in their natural habitat due to the presence of certain undesirable alleles which hamper their yield potential, and thus, their further domestication. CWRs of B. juncea namely include Sinapis alba L. (White mustard), B. tournefortii Gouan. (African mustard), B. fruticulosa Cirillo (Twiggy turnip), Camelina sativa L. (Gold-of-pleasure), Diplotaxis tenuisiliqua Delile (Wall rocket), D. erucoides L. (White wall rocket), D. muralis L. (Annual wall rocket), Crambe abyssinica R.E.Fr. (Abyssinian mustard), Erucastrum gallicum Willd. (Common dogmustard), E. cardaminoides Webb ex Christ (Dogmustard), Capsella bursa-pastoris L. (Shepherds purse), Lepidium sativum L. (Garden Cress) etc. These CWRs have withstood several regimes of biotic and abiotic stresses over the past thousands of years which led them to accumulate many useful alleles contributing in resistance against various environmental stresses. Thus, CWRs could serve as resourceful gene pools for introgression of stress resilience traits into Indian mustard. This review summarizes research work on the introgression of resistance against Sclerotinia stem rot (caused by Sclerotinia sclerotiorum), Alternaria blight (caused by Alternaria brassicae), white rust (caused by Albugo candida), aphid attack, drought and high temperature from CWRs into B. juncea. However, various pre- and post-fertilization barriers due to different ploidy levels are major stumbling blocks in the success of such programmes, therefore, we also insightfully discuss how the advances made in -omics technology could be helpful in assisting various breeding programmes aiming at improvisation of stress resilience traits in B. juncea.

Insights into the Transcriptomics of Crop Wild Relatives to Unravel the Salinity Stress Adaptive Mechanisms

The narrow genomic diversity of modern cultivars is a major bottleneck for enhancing the crop's salinity stress tolerance. The close relatives of modern cultivated plants, crop wild relatives (CWRs), can be a promising and sustainable resource to broaden the diversity of crops. Advances in transcriptomic technologies have revealed the untapped genetic diversity of CWRs that represents a practical gene pool for improving the plant's adaptability to salt stress. Thus, the present study emphasizes the transcriptomics of CWRs for salinity stress tolerance. In this review, the impacts of salt stress on the plant's physiological processes and development are overviewed, and the transcription factors (TFs) regulation of salinity stress tolerance is investigated. In addition to the molecular regulation, a brief discussion on the phytomorphological adaptation of plants under saline environments is provided. The study further highlights the availability and use of transcriptomic resources of CWR and their contribution to pangenome construction. Moreover, the utilization of CWRs' genetic resources in the molecular breeding of crops for salinity stress tolerance is explored. Several studies have shown that cytoplasmic components such as calcium and kinases, and ion transporter genes such as Salt Overly Sensitive 1 (SOS1) and High-affinity Potassium Transporters (HKTs) are involved in the signaling of salt stress, and in mediating the distribution of excess Na⁺ ions within the plant cells. Recent comparative analyses of transcriptomic profiling through RNA sequencing (RNA-Seq) between the crops and their wild relatives have unraveled several TFs, stress-responsive genes, and regulatory proteins for generating salinity stress tolerance. This review specifies that the use of CWRs transcriptomics in combination with modern breeding experimental approaches such as genomic editing, de novo domestication, and speed breeding can accelerate the CWRs utilization in the breeding programs for enhancing the crop's adaptability to saline conditions. The transcriptomic approaches optimize the crop genomes with the accumulation of favorable alleles that will be indispensable for designing salt-resilient crops.

Genomic Survey of Flavin Monooxygenases in Wild and Cultivated Rice Provides Insight into Evolution and Functional Diversities

The flavin monooxygenase (FMO) enzyme was discovered in mammalian liver cells that convert a carcinogenic compound, N-N'-dimethylaniline, into a non-carcinogenic compound, N-oxide. Since then, many FMOs have been reported in animal systems for their primary role in the detoxification of xenobiotic compounds. In plants, this family has diverged to perform varied functions like pathogen defense, auxin biosynthesis, and S-oxygenation of compounds. Only a few members of this family, primarily those involved in auxin biosynthesis, have been functionally characterized in plant species. Thus, the present study aims to identify all the members of the FMO family in 10 different wild and cultivated Oryza species. Genome-wide analysis of the FMO family in different Oryza species reveals that each species has multiple FMO members in its genome and that this family is conserved throughout evolution. Taking clues from its role in pathogen defense and its possible function in ROS scavenging, we have also assessed the involvement of this family in abiotic stresses. A detailed in silico expression analysis of the FMO family in Oryza sativa subsp. japonica revealed that only a subset of genes responds to different abiotic stresses. This is supported by the experimental validation of a few selected genes using qRT-PCR in stress-sensitive Oryza sativa subsp. indica and stress-sensitive wild rice Oryza nivara. The identification and comprehensive in silico analysis of FMO genes from different Oryza species carried out in this study will serve as the foundation for further structural and functional studies of FMO genes in rice as well as other crop types.

Crop Wild Relatives: A Valuable Source of Tolerance to Various Abiotic Stresses

Global climate change is one of the major constraints limiting plant growth, production, and sustainability worldwide. Moreover, breeding efforts in the past years have focused on improving certain favorable crop traits, leading to genetic bottlenecks. The use of crop wild relatives (CWRs) to expand genetic diversity and improve crop adaptability seems to be a promising and sustainable approach for crop improvement in the context of the ongoing climate challenges. In this review, we present the progress that has been achieved towards CWRs exploitation for enhanced resilience against major abiotic stressors (e.g., water deficiency, increased salinity, and extreme temperatures) in crops of high nutritional and economic value, such as tomato, legumes, and several woody perennial crops. The advances in -omics technologies have facilitated the elucidation of the molecular mechanisms that may underlie abiotic stress tolerance. Comparative analyses of whole genome sequencing (WGS) and transcriptomic profiling (RNA-seq) data between crops and their wild relative counterparts have unraveled important information with respect to the molecular basis of tolerance to abiotic stressors. These studies have uncovered genomic regions, specific stress-responsive genes, gene networks, and biochemical pathways associated with resilience to adverse conditions, such as heat, cold, drought, and salinity, and provide useful tools for the development of molecular markers to be used in breeding programs. CWRs constitute a highly valuable resource of genetic diversity, and by exploiting the full potential of this extended allele pool, new traits conferring abiotic-stress tolerance may be introgressed into cultivated varieties leading to superior and resilient genotypes. Future breeding programs may greatly benefit from CWRs utilization for overcoming crop production challenges arising from extreme environmental conditions.

Transgressive Biochemical Response to Water Stress in Interspecific Eggplant Hybrids

In a climate change scenario, crop tolerance to drought must be urgently improved, as it represents an increasingly critical stress reducing agricultural yields worldwide. Although most crops are relatively sensitive to water stress, many of their wild relatives are more tolerant and may be used to improve drought tolerance in our crops. In this study, the response to drought of eggplant (Solanum melongena), its close wild relatives S. insanum and S. incanum and their interspecific hybrids with S. melongena was assessed. The plants were subjected to two treatments for 18 days: control, with irrigation every four days, and drought, with complete interruption of irrigation. Morphological and biomass traits were measured, and physiological and biochemical responses were analysed using stress biomarkers such as proline, flavonoids, and total phenolic compounds. Oxidative stress was quantified by measuring malondialdehyde (MDA) content. As a result of the drought treatment, plant development and tissue water content were seriously affected. Generally, water deficit also caused significant increases in MDA, proline, flavonoids, and total phenolics compounds. Our results comparing parental accessions reveal a better response to drought in one of the S. insanum accessions. The hybrid between S. melongena and S. incanum displayed a better response than the other hybrids and even its parents. The results obtained here might be helpful for future eggplant breeding programmes aimed at improving drought tolerance.