Harnessing the role of mitogen-activated protein kinases against abiotic stresses in plants

miRNA-mRNA integrated analysis reveals candidate genes associated with salt stress response in Halophytic Sonneratia apetala

Sonneratia apetala is a pioneering species of mangrove plants, which has evolved various mechanisms to tolerate salt-stress due to their long-term exposure to a salinized environment as compared to the of terrestrial freshwater plants. However, limited attempt has been made to uncover the underlying molecular mechanism of their saline adaptation. Here, we integrated mRNA and microRNA (miRNA) sequencing to identify the genes and pathways that may be involved in salt stress-response in the roots of S. apetala. A comprehensive full‑length transcriptome containing 295,501 high‑quality unigenes was obtained by PacBio sequencing technology. Of these, 6,686 genes exhibited significantly differential accumulation after salt stress treatment (p < 0.001, Q < 0.01). They were mainly implicated in plant signal transduction and diverse metabolic pathways, such as those involving phenylpropanoid biosynthesis, plant-pathogen interaction and protein processing. Also, our results identified the regulatory interaction between miRNA-target counterparts during salt stress. Taken together, we present the first global overview of the transcriptome of S. apetala roots, and identify potentially important genes and pathways associated with salt tolerance for further investigation. This study is expected to deliver novel insights in understanding the regulatory mechanism in S. apetala response to salt stress.

Harnessing the interplay of protein posttranslational modifications: Enhancing plant resilience to heavy metal toxicity

Heavy metals (HMs) toxicity finds substantial plant health risk, affecting germination, growth, productivity, and survival. HMs exposure can interrupt cellular function, increase oxidative stress and affect physiological processes. Plants have developed array of adaptive responses, with proteins playing key role in detecting, signalling, and mitigating metal-induced stress. Under stress, posttranslational modifications, including phosphorylation, ubiquitination, glycosylation and acetylation, are essential regulators of protein stability, localization, and function. This review examines the comprehensive profiling of PTMs in HMs stress responses, including how PTMs regulate the signalling pathways, degradation pathways, and TFs modulation. Specifically, discuss the role of phosphorylation, ubiquitination, and sumoylation, neddylation, lipidation, and S-nitrosylation in specifically under HMs stress with PTMs regulation of antioxidant enzymes, stress proteins, metal transporters and chelators of detoxification. This review illustrates the crosstalk of PTMs to show how synergistic interactions regulate protein stability, activity, and localization upon HMs stress. In cross talk, ubiquitination often starts from phosphorylation to subsequent degradation of proteins in a timely and reversible way to trigger stress responses. However, sumoylation stabilizes key transcription factors that are rapidly dephosphorylated and integral in metal detoxification, form a synergistic combination with phosphorylation to maintain their activity. It explains the future research directions, focusing on PTM engineering to generate stress tolerant plant varieties. By studying the response of plants to HMs stress through PTMs, emphasizes the relevance of PTMs towards plant resilience and advocates for systems biology integrative approach to advancing plant stress biology.

Variation in flower frost tolerance among seven apple cultivars and transcriptome response patterns in two contrastingly frost-tolerant selected cultivars

This study evaluated frost tolerance in flowers of seven major apple cultivars grown in Korea to develop frost-resistant varieties for sustainable apple production under climate change. Flowers at full bloom were exposed to simulated frost conditions at -2°C, and frost damage was assessed using the total flower frost damage rate and King flower frost damage rate. Over 3 years, "Arisoo" consistently exhibited strong frost tolerance, whereas 'Fuji' was frost-sensitive. Transcriptomic analysis revealed significant differences in gene expression both within cultivars under different treatments and between cultivars under identical conditions. A higher number of differentially expressed genes were upregulated under frost stress in both cultivars, indicating key regulatory mechanisms involved in frost adaptation. Functional annotation and Kyoto Encyclopedia of Genes and Genome pathway analysis identified plant hormone signaling, mitogen-activated protein kinase signaling, and starch and sucrose metabolism can contribute to frost tolerance. Our findings offer critical insights into the genetic and molecular mechanisms of frost tolerance, contributing to the development of resilient apple varieties and sustainable production systems under climate change.

Genome-wide identification and molecular characterization of the MAPK family members in sand pear (Pyrus pyrifolia)

BACKGROUND

'Whangkeumbae', a highly regarded variety of sand pear, is celebrated in the market for its distinctive and superior flavor. However, the rapid production of ethylene after harvest significantly shortens its shelf life, becoming a major limiting factor for enhancing its commercial value. Mitogen-activated protein kinases (MAPKs) are a highly conserved family of transferases in eukaryotes. Although the importance of this family has been extensively studied in other plants, the precise composition and functional mechanisms of MAPK members in sand pear remain elusive. A genome-wide identification and molecular characterization of the MAPK gene family were conducted in Pyrus pyrifolia. This comprehensive analysis aimed to elucidate the genomic distribution, evolutionary relationships, and potential biological roles of MAPK genes in fruit senescence.

RESULTS

Four PpMAPKs were identified from our transcriptome data of sand pear, and 22 PpMAPK proteins were identified from the sand pear genome. Specifically, the transcriptomic PpMAPK3-L (GenBank accession number: PP992971), PpMAPK7-L (GenBank accession number: PP992972), PpMAPK10-L (GenBank accession number: PP992973), and PpMAPK16-L (GenBank accession number: PP992974) exhibited sequence homology values of 99.19%, 100%, 94.51%, and 95.75%, respectively, with their corresponding genomic counterparts (EVM0007944.1, EVM0004426.1, EVM0023771.1, EVM0027166.1). These findings indicate that the integrated analysis of transcriptomic and genomic data provides critical genetic insights into the MAPK genes in sand pear, culminating in the identification of a total of 25 PpMAPK genes in this species. Further phylogenetic analysis classified these genes into four subfamilies (A, B, C, and D), with subfamilies A and B each comprising six members, subfamily C with four members, and subfamily D with nine members. The potential functional differences among the gene members of each subfamily provide valuable clues for future research into MAPK signaling pathways. Further analysis by qRT-PCR revealed that the expression of four PpMAPK genes was positively correlated with fruit senescence in Pyrus pyrifolia. Additionally, interaction analysis revealed a significant interaction between PpMAPK3-L and PpbZIP2, which coordinatively regulate the senescence traits of fruits in sand pear through their joint influence during the senescence process.

CONCLUSION

The results of this study suggest that PpMAPK3-L, PpMAPK7-L, PpMAPK10-L, and PpMAPK16-L are likely to play pivotal roles in the maturation and senescence of sand pear fruit. Specifically, the interaction between PpMAPK3-L and PpbZIP2 could play a key role in the regulation of fruit senescence, indicating that the MAPK signaling pathway may modulate the fruit's physiological state through interactions with transcription factors. This finding offers significant insights for further investigation into the functions of MAPK genes in the maturation and senescence of sand pear fruit and provides a new direction for investigating biotechnological approaches for delaying senescence and prolonging shelf life.

Mapping stress memory: genetic and epigenetic insights into combined drought and heat tolerance in barley

KEY MESSAGE

Unveiling genetic and epigenetic mechanisms in barley, this study maps stress memory under combined drought and heat, advancing resilience breeding for climate-adaptive crop improvement. Barley is one of the world's most important cereal crops and is increasingly threatened by concurrent drought and heat stress, two major environmental factors intensified by climate change. In our study, we employed a genome-wide association scan (GWAS) to investigate the concept of "stress memory," wherein barley plants exposed to previous stress events exhibit enhanced responses to subsequent ones. We evaluated key agronomic traits, such as plant height, spike length, grain number, and thousand kernel weight along with biochemical markers such as chlorophyll content, proline, and soluble proteins across three generations under combined drought and heat stress. This approach encompassed transgenerational and intergenerational stress memory and a third generation that could reveal the potential cumulative effects of combined drought and heat stress. Our findings demonstrated a significant increase in metabolites specifically proline and soluble proteins in third-generation barley plants compared to those exposed to stress for only one or two generations. Through GWAS analysis, we identified 332 highly significant SNP markers clustered within 14 genomic regions on chromosomes 2H, 3H, 4H, 5H, and 7H. These regions are associated with all evaluated physiological and morphological traits under stress that harbor several potential candidate genes implicated in regulating complex signaling pathways, reactive oxygen species scavenging, and energy metabolism processes essential for mitigating the impacts of drought and heat. These results underscore the intricate nature of barley's stress tolerance mechanisms and highlight the potential for integrating genomics, epigenomics, and advanced phenotyping approaches into breeding programs.

ZjMAPKK4 Interacted With ZjNAC78 Regulates Cold Tolerance Response in Jujube

Jujube (Ziziphus jujuba Mill.) holds great importance as a fruit tree in China, with strong tolerance to drought and saline stress, but its growth is limited by vulnerability to cold stress. Consequently, the role of MAPK cascades in mediating jujube cold stress response remains unclear, with the specific function of ZjMAPKK4 in this context yet to be fully elucidated. Thus, in the current study, it was found that ZjMAPKK4 was significantly upregulated compared with other ZjMAPK cascade genes after cold treatment. Heterologous transformation of ZjMAPKK4 in Arabidopsis, VIGS-induced ZjMAPKK4 transiently silencing and overexpression of ZjMAPKK4 in jujube callus assays demonstrated that ZjMAPKK4 positively regulated the cold resistance of jujube. Furthermore, to elucidate the molecular regulation mechanism behind ZjMAPKK4 under cold stress, 25 key DEGs were screened out by transcriptome analysis. Yeast screening cDNA library, yeast two-hybrid, LCA and Co-IP analysis showed ZjMAPKK4 interacted with ZjNAC78 and VIGS-induced ZjNAC78 silenced sour jujube plants showed cold sensitivity and the expression level of cold response genes were downregulated after cold stress. All the results demonstrated that ZjMAPKK4 could interact with ZjNAC78 to regulate the downstream ZjICE-ZjCBF genes to regulate the cold tolerance of jujube.

Identification of key genes and signaling pathways in coconut (Cocos nucifera L.) under drought stress via comparative transcriptome analysis

BACKGROUND

Drought stress has become a pervasive environmental challenge, significantly impacting all stages of plant growth and development under changing climatic conditions worldwide. In coconut, drought stress critically impairs reproductive development, notably reducing the quality of pollen and gametes during fertilization. Therefore, the seedlings of the aromatic coconut variety were subjected to drought stress for varying durations: control (no stress), 7 days, 14 days, and 21 days to find the potential molecular mechanisms and genes related to coconut drought tolerance through transcriptomic analysis. Our study may provide a theoretical basis for investigations into drought stress tolerance that will be useful for further coconut improvement.

RESULTS

We assessed antioxidant enzyme activity and conducted comparative transcriptome analyses of aromatic coconut under different drought conditions (7, 14, and 21 days). Our findings revealed significant rises in superoxide dismutase (SOD), peroxidase (POD) activities and proline (Pro) content across all drought periods compared to control plants, suggesting that these enzymes play a crucial role in the adaptive response of coconuts to drought stress. RNA-seq data identified 280, 729, and 6,698 differentially expressed genes (DEGs) at 7, 14, and 21 days, respectively. Principal Component Analysis (PCA) revealed that coconut samples were scattered and separated across different treatment points, suggesting the presence of differentially expressed genes (DEGs), particularly in the 21 day drought treatment (GH21d). KEGG pathway analysis indicated that DEGs were significantly enriched in pathways related to plant-pathogen interaction, plant hormone signaling, and mitogen-activated protein kinase (MAPK) signaling. Functional annotation of these DEGs revealed key candidate genes involved in several hormone signaling pathways, including abscisic acid (ABA), jasmonates (JA), auxin (AUX), brassinosteroids (BR), ethylene (ET), and gibberellin (GA), along with MAPK pathway which may regulate plant adaptation to drought stress through processes such as plant growth, cell division, stomatal closure, root growth, and stomatal development. This study provides valuable insights into the genetic and molecular basis of drought tolerance in coconuts, paving the way for the improvement of drought-tolerant coconut varieties.

CONCLUSIONS

Under drought stress, the expression of genes related to plant growth, stomatal closure, cell division, stress response, adaptation, and stomatal development appears to play a critical role in drought tolerance in coconut. Our results revealed that multiple genes may contribute to the drought tolerance mechanism in coconut through various hormone signaling pathways, including ABA, JA, auxin, BR, GA, and ethylene. These findings offer new insights into the key molecular mechanisms governing drought tolerance in aromatic coconut. Furthermore, the candidate genes and pathways identified in this study could be valuable for developing strategies to enhance drought tolerance in coconut plants.

CLINICAL TRIAL NUMBER

Not Applicable.

The dynamics of N6-methyladenine RNA modification in resistant and susceptible rice varieties responding to rice stem borer damage

N6-methyladenosine (m6A) is the most prevalent modification in cellular RNA which orchestrates diverse physiological and pathological processes during stress response. However, the differential m6A modifications that cope with herbivore stress in resistant and susceptible crop varieties remain unclear. Here, we found that rice stem borer (RSB) larvae grew better on indica rice (e.g., MH63, IR64, Nanjing 11) than on japonica rice varieties (e.g., Nipponbare, Zhonghua 11, Xiushui 11). Then, transcriptome-wide m6A profiling of representative resistant (Nipponbare) and susceptible (MH63) rice varieties were performed using a nanopore direct RNA sequencing approach, to reveal variety-specific m6A modifications against RSB. Upon RSB infestation, m6A methylation occurred in actively expressed genes in Nipponbare and MH63, but the number of methylation sites decreased across rice chromosomes. Integrative analysis showed that m6A methylation levels were closely associated with transcriptional regulation. Genes involved in herbivorous resistance related to mitogen-activated protein kinase, jasmonic acid (JA), and terpenoid biosynthesis pathways, as well as JA-mediated trypsin protease inhibitors, were heavily methylated by m6A, and their expression was more pronounced in RSB-infested Nipponbare than in RSB-infested MH63, which may have contributed to RSB resistance in Nipponbare. Therefore, dynamics of m6A modifications act as the main regulatory strategy for expression of genes involved in plant-insect interactions, which is attributed to differential responses of resistant and susceptible rice varieties to RSB infestation. These findings could contribute to developing molecular breeding strategies for controlling herbivorous pests.

Enhancing wheat resilience: biotechnological advances in combating heat stress and environmental challenges

Climate change, with its increasing temperatures, is significantly disrupting global agricultural systems, and wheat, a key cereal crop faces severe challenges. Heat stress has emerged as a critical threat, accelerating wheat growth, leading to premature maturation, reduced grain filling, and ultimately lower yields. The situation is exacerbated by more frequent and intense heat waves, particularly in regions already struggling with water scarcity. Maintaining the delicate balance of temperature and water necessary for optimal wheat production is becoming challenging, posing a serious risk to global food security. Therefore, there is an urgent need to develop adaptive strategies with innovations in breeding and transgenic technologies crucial to improving wheat resilience to environmental stresses, especially to combat the growing impacts of heat stress. Modern tools like CRISPR/Cas9, Transcription Activator-Like Effector Nucleases, and Zinc Finger Nucleases have been instrumental in developing wheat varieties with improved traits. However, the future of wheat cultivation requires more than just resistance to a single stressor. As climate change intensifies, there is an urgent need for wheat varieties that can withstand multiple stresses, including heat, drought, and pests. Developing these multi-stress-tolerant cultivars is crucial for ensuring food security in a rapidly changing climate.

Molecular Mechanisms of Alfalfa Response to Abiotic Stresses

Alfalfa (Medicago sativa L.), a high-quality perennial legume forage, is pivotal in global animal husbandry and ecological systems. However, its growth and production are threatened by various abiotic stresses, including drought, salinity, low temperatures, and heavy metal toxicity. This review summarizes recent research on the molecular mechanisms underlying alfalfa's responses to these environmental adversities. It provides a theoretical foundation for enhancing the stress resistance of alfalfa, offering a valuable reference for breeding high-quality, stress-resistant alfalfa varieties.

Tomato mitogen-activated protein kinase: mechanisms of adaptation in response to biotic and abiotic stresses

Plants live under various biotic and abiotic stress conditions, and to cope with the adversity and severity of these conditions, they have developed well-established resistance mechanisms. These mechanisms begin with the perception of stimuli, followed by molecular, biochemical, and physiological adaptive measures. Tomato (Solanum lycopersicum) is a globally significant vegetable crop that experiences several biotic and abiotic stress events that can adversely impact its quality and production. Mitogen-activated protein kinases (MAPKs) in tomato plants have crucial functions of mediating responses to environmental cues, internal signals, defense mechanisms, cellular processes, and plant development and growth. MAPK cascades respond to various environmental stress factors by modulating associated gene expression, influencing plant hormone synthesis, and facilitating interactions with other environmental stressors. Here, we review the evolutionary relationships of 16 tomato SlMAPK family members and emphasize on recent studies describing the regulatory functions of tomato SlMAPKs in both abiotic and biotic stress conditions. This review could enhance our comprehension of the MAPK regulatory network in biotic and abiotic stress conditions and provide theoretical support for breeding tomatoes with agronomic traits of excellent stress resistance.

Advances in Protein Kinase Regulation of Stress Responses in Fruits and Vegetables

Fruits and vegetables (F&Vs) are essential in daily life and industrial production. These perishable produces are vulnerable to various biotic and abiotic stresses during their growth, postharvest storage, and handling. As the fruit detaches from the plant, these stresses become more intense. This unique biological process involves substantial changes in a variety of cellular metabolisms. To counter these stresses, plants have evolved complex physiological defense mechanisms, including regulating cellular activities through reversible phosphorylation of proteins. Protein kinases, key components of reversible protein phosphorylation, facilitate the transfer of the γ-phosphate group from adenosine triphosphate (ATP) to specific amino acid residues on substrates. This phosphorylation alters proteins' structure, function, and interactions, thereby playing a crucial role in regulating cellular activity. Recent studies have identified various protein kinases in F&Vs, underscoring their significant roles in plant growth, development, and stress responses. This article reviews the various types of protein kinases found in F&Vs, emphasizing their roles and regulatory mechanisms in managing stress responses. This research sheds light on the involvement of protein kinases in metabolic regulation, offering key insights to advance the quality characteristics of F&Vs.

Influence of rhizospheric symbiotic microorganisms on the behavioural effects of antimony in soil-plant system: Insights from a proteomic perspective

Antimony (Sb) pollution in soil-rice systems can affect human health by enriching of food chains. Currently, the mechanism of the negative role underlying microorganisms in plant responses to Sb stress remains clear. The results of this study showed that the presence of arbuscular mycorrhizal (AM) fungi, a common symbiotic microorganism in rhizosphere soil, significantly enhanced Sb uptake by upland rice and inhibited its growth. Furthermore, we explained the reasons for the adverse effects of AM fungi mediation on upland rice growth under Sb stress from a molecular perspective. The results also showed that AM fungi affect the biological processes of the response of upland rice to oxidative stress and the functions of its antioxidant active molecules throughout the vegetative growth phase of upland rice, and that the phenylpropanoid biosynthesis pathway is significantly downregulated. At the same time, phenylalanine/tyrosine ammonia-lyase (PTAL) in the pathway was significantly expressed in the middle and late stages of vegetative growth of upland rice. Therefore, PTAL can act as a potential reference protein to investigate the response of upland rice to Sb stress mediated by AM fungi. These findings enrich our understanding of the impact of Sb pollution on soil-plant systems in real soil environments.

Identification of MAPK Genes in Phaseolus vulgaris and Analysis of Their Expression Patterns in Response to Anthracnose

The oil bean is a high-quality, economically valuable variety of kidney bean (Phaseolus vulgaris L.) that is widely cultivated in Northeast China. However, the prevalence of anthracnose, caused by a combination of factors, including continuous cropping over many years, has led to significant declines in both yield and quality. The mitogen-activated protein kinase (MAPK) cascade is a highly conserved plant cell signaling pathway that plays a pivotal role in plant growth and development, as well as responses to biotic stress. However, its role in the response of P. vulgaris to anthracnose infection has not previously been reported. We identified and characterized thirteen MAPK genes (PvMAPK01-PvMAPK13) in the P. vulgaris genome. These genes were found on eight of the eleven chromosomes of P. vulgaris, and phylogenetic analyses classified them into four previously established subgroups (A-D). Analysis of the cis-acting elements in their promoter regions revealed the presence of multiple elements associated with light, hormone regulation, stress responses, and growth and development. An analysis of intraspecific collinearity revealed that whole-genome and/or segmental duplication, rather than tandem duplication, has been the primary driver of PvMAPK family expansion in P. vulgaris. Transcriptome data revealed that the PvMAPKs differed in their tissue-specific expression patterns, with PvMAPK05 showing particularly high expression in stems and stem tips and PvMAPK07 and PvMAPK11 showing relatively low expression across all tissues. In general, expression of the PvMAPKs was higher in stems, stem tips, and pods than in other tissues and organs, suggesting that they may be particularly important for regulating stem and pod development. Analysis of the expression of PvMAPKs in field-grown plants infected or uninfected with anthracnose revealed that the relative expression levels of PvMAPK05, PvMAPK07, PvMAPK09, and PvMAPK11 exhibited particularly significant changes in response to anthracnose infection across different varieties, suggesting their potential involvement in the anthracnose response of Phaseolus vulgaris. This study reports the fundamental characteristics of the thirteen MAPK genes in P. vulgaris, documents their expression patterns in diverse tissues, and offers preliminary insights into their responses to anthracnose infection, establishing a foundation for subsequent functional validation.

Silicon might mitigate nickel toxicity in maize roots via chelation, detoxification, and membrane transport

Nickel is an essential micronutrient for plant growth and development. However, in excessive amounts caused by accidental pollution of soils, this heavy metal is toxic to plants. Although silicon is a non-essential nutrient, it accumulates in most monocots, particularly the vital crop maize (corn, Zea mays). In fact, this metalloid mineral can alleviate the toxicity of heavy metals, though the mechanism is not entirely clear yet. Herein, we measured proteome, gene expression, enzyme activities, and selected sugars to investigate such effect thoroughly. Deep proteomic analysis revealed a minor impact of 100 µM Ni, 2.5 mM Si, or their combination on roots in 12-day-old hydroponically grown maize seedlings upon 9 days of exposure. Nonetheless, we suggested plausible mechanisms of Si mitigation of excessive Ni: Chelation by metallothioneins and phytochelatins, detoxification by glycine betaine pathway, and restructuring of plasma membrane transporters. Higher activity of glutathione S-transferase confirmed its plausible involvement in reducing Ni toxicity in combined treatment. Accumulation of sucrose synthase and corresponding soluble sugars in Ni and combined treatment implied high energy requirements both during heavy metal stress and its mitigation. Expression analysis of genes coding a few differentially accumulated proteins failed to reveal concordant changes, indicating posttranscriptional regulation. Proposed mitigation mechanisms should be functionally validated in follow-up studies.

Molecular traits of MAPK kinases and the regulatory mechanism of GhMAPKK5 alleviating drought/salt stress in cotton

Mitogen-activated protein kinase kinases (MAPKKs) play a critical role in the mitogen-activated protein kinase (MAPK) signaling pathway, transducing external stimuli into intracellular responses and enabling plant adaptation to environmental challenges. Most research has focused on the model plant Arabidopsis (Arabidopsis thaliana). The systematic analysis and characterization of MAPKK genes across different plant species, particularly in cotton (Gossypium hirsutum), are somewhat limited. Here, we identified MAPKK family members from 66 different species, which clustered into five different sub-groups, and MAPKKs from four cotton species clustered together. Through further bioinformatic and expression analyses, GhMAPKK5 was identified as the most responsive MAPKK member to salt and drought stress among the 23 MAPKKs identified in Gossypium hirsutum. Silencing GhMAPKK5 in cotton through virus-induced gene silencing (VIGS) led to quicker wilting under salt and drought conditions, while overexpressing GhMAPKK5 in Arabidopsis enhanced root growth and seed germination under these stresses, demonstrating GhMAPKK5's positive role in stress tolerance. Transcriptomics and Yeast-Two-Hybrid assays revealed a MAPK cascade signal module comprising GhMEKK (mitogen-activated protein kinase kinase kinases)3/8/31-GhMAPKK5-GhMAPK11/23. This signaling cascade may play a role in managing drought and salt stress by regulating transcription factor genes, such as WRKYs, which are involved in the biosynthesis and transport pathways of ABA, proline, and RALF. This study is highly important for further understanding the regulatory mechanism of MAPKK in cotton, contributing to its stress tolerance and offering potential in targets for genetic enhancement.

StMAPK10 gene functional identification and analysis in drought resistance of potato crop (Solanum tuberosum L.)

All over the world, potato (Solanum tuberosum L.) production is constrained by several biotic and abiotic factors. Many techniques and mechanisms have been used to overcome these hurdles and increase food for the rising population. In crop plants, the mitogen-activated protein kinase (MAPK) cascade, a significant regulator of the MAPK pathway under various biotic and abiotic stress conditions, is one of the targets to increase productivity. MAPK plays a significant role under drought stress in potato. However, the function of MAPK in drought resistance in potato is poorly understood. In this study, we wanted to identify the function of StMAPK10 in the drought resistance in potato. StMAPK10 was up-regulated under drought conditions and dynamically modulated by abiotic stresses. Over-expression and down-regulation of StMAPK10 revealed that StMAPK10 stimulated potato growth under drought conditions, as demonstrated by changes in SOD, CAT, and POD activity, as well as H2O2, proline, and MDA content. StMAPK10 up-regulation exaggerated the drought resistance of the potato plant by uplifting antioxidant activities and photosynthetic indices. Overexpressed-StMAPK10 potato lines showed highly significant results for physiological and photosynthetic indices in response to drought stress, while knockdown expression showed opposite outcomes. Additionally, subcellular localization and phenotypic analysis of transgenic and non-transgenic plants substantiated the role of the increased expression of StMAPK10 against drought stress. The results could provide novel insights into the functionality of StMAPK10 in drought responses and conceivable mechanisms.

Insight into the relationship between metabolic enzymes and oxadiazon degradation in Oryza sativa for reducing environmental risks

Oxadiazon (ODZ) is extensively utilized in agricultural fields for weed control owing to its strong effectiveness. However, excessive loading of ODZ in water bodies and agricultural soils can lead to various environmental concerns. Therefore, it is crucial to understand the ODZ metabolic process and associated mechanisms in crops to assess the likelihood of ODZ contamination in the environment. This study aimed to assess the effects of ODZ on the growth and toxicological responses of rice (Oryza sativa). The growth of rice tissues was notably compromised with the increase in ODZ concentrations. RNA sequencing in combination with liquid chromatography-quadrupole-time-of-flight-high-resolution mass spectrometry/mass spectrometry (LC-Q-TOF-HRMS/MS) analysis allowed for the identification of numerous transcriptional components associated with ODZ metabolism. Four libraries comprising rice roots and shoots exposed to ODZ were RNA-sequenced in triplicate. The application of environmentally realistic ODZ concentrations upregulated the expression of 844 genes in shoots and 1476 genes in roots. Gene enrichment analysis revealed the presence of multiple enzymes involved in ODZ metabolism and detoxification. These enzymes play a critical role in mitigating environmental stress and facilitating xenobiotic metabolism. Notably, among differentially expressed genes, several key enzymes were identified, including cytochrome P450s, protein kinases, aminotransferases, and ATP-binding cassette transporters involved in the metabolic process. Using LC-Q-TOF-HRMS/MS, 3 metabolites and 13 conjugates were identified in multiple metabolic pathways involving oxidation, hydrolysis, glycosylation, acetylation, and methylation. This study successfully established a potential link between the specific metabolic products of ODZ and increased activities of their corresponding enzymes. Moreover, this study considerably elucidates the detailed pathways and mechanisms involved in ODZ metabolism. The study findings provide valuable insights into the development of genotypes for reducing ODZ residues in paddy fields and minimizing their accumulation in rice crops.

Comprehensive analysis of MAPK gene family in upland cotton (Gossypium hirsutum) and functional characterization of GhMPK31 in regulating defense response to insect infestation

KEY MESSAGE

The transcriptomic, phenotypic and metabolomic analysis of transgenic plants overexpressing GhMPK31 in upland cotton revealed the regulation of H2O2 burst and the synthesis of defensive metabolites by GhMPK31. Mitogen-activated protein kinases (MAPKs) are a crucial class of protein kinases, which play an essential role in various biological processes in plants. Upland cotton (G. hirsutum) is the most widely cultivated cotton species with high economic value. To gain a better understanding of the role of the MAPK gene family, we conducted a comprehensive analysis of the MAPK gene family in cotton. In this study, a total of 55 GhMPK genes were identified from the whole genome of G. hirsutum. Through an investigation of the expression patterns under diverse stress conditions, we discovered that the majority of GhMPK family members demonstrated robust responses to abiotic stress, pathogen stress and pest stress. Furthermore, the overexpression of GhMPK31 in cotton leaves led to a hypersensitive response (HR)-like cell death phenotype and impaired the defense capability of cotton against herbivorous insects. Transcriptome and metabolomics data analysis showed that overexpression of GhMPK31 enhanced the expression of H2O2-related genes and reduced the accumulation of defensive related metabolites. The direct evidence of GhMPK31 interacting with GhRBOHB (H2O2-generating protein) were found by Y2H, BiFC, and LCI. Therefore, we propose that the increase of H2O2 content caused by overexpression of GhMPK31 resulted in HR-like cell death in cotton leaves while reducing the accumulation of defensive metabolites, ultimately leading to a decrease in the defense ability of cotton against herbivorous insects. This study provides valuable insights into the function of MAPK genes in plant resistance to herbivorous insects.

Calcium-Dependent Protein Kinase 5 (OsCPK5) Overexpression in Upland Rice (Oryza sativa L.) under Water Deficit

Water deficit significantly affects global crop growth and productivity, particularly in water-limited environments, such as upland rice cultivation, reducing grain yield. Plants activate various defense mechanisms during water deficit, involving numerous genes and complex metabolic pathways. Exploring homologous genes that are linked to enhanced drought tolerance through the use of genomic data from model organisms can aid in the functional validation of target species. We evaluated the upland rice OsCPK5 gene, an A. thaliana AtCPK6 homolog, by overexpressing it in the BRSMG Curinga cultivar. Transformants were assessed using a semi-automated phenotyping platform under two irrigation conditions: regular watering, and water deficit applied 79 days after seeding, lasting 14 days, followed by irrigation at 80% field capacity. The physiological data and leaf samples were collected at reproductive stages R3, R6, and R8. The genetically modified (GM) plants consistently exhibited higher OsCPK5 gene expression levels across stages, peaking during grain filling, and displayed reduced stomatal conductance and photosynthetic rate and increased water-use efficiency compared to non-GM (NGM) plants under drought. The GM plants also exhibited a higher filled grain percentage under both irrigation conditions. Their drought susceptibility index was 0.9 times lower than that of NGM plants, and they maintained a higher chlorophyll a/b index, indicating sustained photosynthesis. The NGM plants under water deficit exhibited more leaf senescence, while the OsCPK5-overexpressing plants retained their green leaves. Overall, OsCPK5 overexpression induced diverse drought tolerance mechanisms, indicating the potential for future development of more drought-tolerant rice cultivars.

Gene Expression and Interaction Analysis of FsWRKY4 and FsMAPK3 in Forsythia suspensa

Forsythia suspensa is a deciduous shrub that belongs to the family Myrtaceae, and its dried fruits are used as medicine. F. suspensa contains several secondary metabolites, which exert pharmacological effects. One of the main active components is forsythin, which exhibits free radical scavenging, antioxidant, anti-inflammatory, and anti-cancer effects. Mitogen-activated protein kinase (MAPKs) can increase the activity of WRKY family transcription factors in a phosphorylated manner, thereby increasing the content of secondary metabolites. However, the mechanism of interaction between MAPKs and WRKYs in F. suspensa remains unclear. In this study, we cloned the genes of FsWRKY4 and FsMAPK3, and performed a bioinformatics analysis. The expression patterns of FsWRKY4 and FsMAPK3 were analyzed in the different developmental stages of leaf and fruit from F. suspensa using real-time fluorescence quantitative PCR (qRT-PCR). Subcellular localization analysis of FsWRKY4 and FsMAPK3 proteins was performed using a laser scanning confocal microscope. The existence of interactions between FsWRKY4 and FsMPAK3 in vitro was verified by yeast two-hybridization. Results showed that the cDNA of FsWRKY4 (GenBank number: OR566682) and FsMAPK3 (GenBank number: OR566683) were 1587 and 522 bp, respectively. The expression of FsWRKY4 was higher in the leaves than in fruits, and the expression of FsMAPK3 was higher in fruits but lower in leaves. The subcellular localization results indicated that FsWRKY4 was localized in the nucleus and FsMAPK3 in the cytoplasm and nucleus. The prey vector pGADT7-FsWRKY4 and bait vector pGBKT7-FsMAPK3 were constructed and co-transferred into Y2H Glod yeast receptor cells. The results indicated that FsWRKY4 and FsMAPK3 proteins interact with each other in vitro. The preliminary study may provide a basis for more precise elucidation of the synthesis of secondary metabolites in F. suspensa.

StMAPK1 functions as a thermos-tolerant gene in regulating heat stress tolerance in potato (Solanum tuberosum)

Background and aims

Mitogen-activated protein kinases (MAPKs) have been reported to respond to various stimuli including heat stress. This research aimed to investigate whether StMAPK1 is implicated in the transduction of the heat stress signal to adapt heat stress as a thermos-tolerant gene.

Materials and methods

Potato plants were cultivated under mild (30°C) and acute (35°C) heat stress conditions to analyze mRNA expression of StMAPKs and physiological indicators. StMAPK1 was up-regulated and down-regulated by transfection. Subcellular localization of StMAPK1 protein was observed by fluorescence microscope. The transgenic potato plants were assayed for physiological indexes, photosynthesis, cellular membrane integrity, and heat stress response gene expression.

Results

Heat stress altered the expression prolife of StMAPKs. StMAPK1 overexpression changed the physiological characteristics and phenotypes of potato plants under heat stresses. StMAPK1 mediates photosynthesis and maintains membrane integrity of potato plants in response to heat stress. Stress response genes (StP5CS, StCAT, StSOD, and StPOD) in potato plants were altered by StMAPK1 dysregulation. mRNA expression of heat stress genes (StHSP90, StHSP70, StHSP20, and StHSFA3) was affected by StMAPK1.

Conclusions

StMAPK1 overexpression increases the heat-tolerant capacity of potato plants at the morphological, physiological, molecular, and genetic levels.