Thioredoxin h2 inhibits the MPKK5-MPK3 cascade to regulate the CBF-COR signaling pathway in Citrullus lanatus suffering chilling stress

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.

Genome-wide identification and characterization of the thioredoxin (TRX) gene family in tomato (Solanum lycopersicum) and a functional analysis of SlTRX2 under salt stress

Thioredoxin is a multifunctional acidic protein widely presented in organisms that regulates intracellular redox processes, participating in a series of biochemical reactions in cells to affect the growth and development of plants. Although the thioredoxin (TRX) gene family has been widespread recognized across various plant species, and the tomato genome has been sequenced for years now, of tomato (Solanum lycopersicum) has remained largely uncharted in terms of identifying and unraveling the functional intricacies of is TRX genes. In this study, 53 SlTRX genes were identified, unevenly distributed across 11 of the 12 tomato chromosomes. These 53 SlTRX genes were categorized into 4 distinct subfamilies based on their evolutionary kinship and phylogenetic development. Expression profiling reveals that most of SlTRX genes exhibited distinct expression patterns across various tissues and developmental stages. In addition, the gene structure, conserved protein motifs and cis-elements of 53 SlTRX genes were analyzed simultaneously. In our rigorous in silico expression analysis, 8 SlTRX genes were meticulously selected for subsequent experiments. Subcellular localization indicated that these 8 SlTRX genes were localized in chloroplasts. Furthermore, these 8 SlTRX genes were responsive to abiotic stress (salt, drought and cold stress) under the qRT-PCR analysis, and their different expression patterns under diverse types of treatments indicated their possible roles in stress tolerance in tomato. Based on these results, SlTRX2, whose expression level continued to increase under salt stress, was selected for silencing to further investigate its function, and furthermore, silencing SlTRX2 inhibited plant growth and led to a significant reduction in photosynthesis under salt stress. Yeast two-hybrid and luciferase complementation imaging assays demonstrated that SlTRX2 may regulate tomato salt resistance by affecting related photosynthetic genes. Thus, our study establishes a valuable resource for further analysis on biological functions of SlTRX genes and will provide important insights in the mechanism of action under stress.

Aquaporin CmPIP2;3 links H2O2 signal and antioxidation to modulate trehalose-induced cold tolerance in melon seedlings

Cold stress severely restricts the growth and development of cold-sensitive crops. Trehalose (Tre), known as the "sugar of life", plays key roles in regulating plant cold tolerance by triggering antioxidation. However, the relevant regulatory mechanism remains unclear. Here, we confirmed that Tre triggers apoplastic hydrogen peroxide (H2O2) production and thus plays key roles in improving the cold tolerance of melon (Cucumis melo var. makuwa Makino) seedlings. Moreover, Tre treatment can promote the transport of apoplastic H2O2 to the cytoplasm. This physiological process may depend on aquaporins. Further studies showed that a Tre-responsive plasma membrane intrinsic protein 2;3 (CmPIP2;3) had strong H2O2 transport function and that silencing CmPIP2;3 significantly weakened apoplastic H2O2 transport and reduced the cold tolerance of melon seedlings. Yeast library and protein-DNA interaction technology were then used to screen 2 Tre-responsive transcription factors, abscisic acid-responsive element (ABRE)-binding factor 2 (CmABF2) and ABRE-binding factor 3 (CmABF3), which can bind to the ABRE motif of the CmPIP2;3 promoter and activate its expression. Silencing of CmABF2 and CmABF3 further dramatically increased the ratio of apoplastic H2O2/cytoplasm H2O2 and reduced the cold tolerance of melon seedlings. This study uncovered that Tre treatment induces CmABF2/3 to positively regulate CmPIP2;3 expression. CmPIP2;3 subsequently enhances the cold tolerance of melon seedlings by promoting the transport of apoplastic H2O2 into the cytoplasm for conducting redox signals and stimulating downstream antioxidation.

TRX h2-PP2AC2 module serves as a convergence node for aluminum stress and leaf senescence signals, regulating cell death via ABA-mediated ROS pathway

ROS/redox signaling plays an important role in the regulation of signal transduction and acclimation pathways activated by multiple abiotic stresses and leaf senescence. However, the regulatory events that produce ROS under different stimuli are far from clear. Here, we report the elucidation of the molecular mechanism of an h type thioredoxin, AhTRX h2, positively regulates Al sensitivity and leaf senescence by promoting ROS. AhTRX h2 transcript levels increased greatly during both natural senescence and Al stress condition in peanut. Ectopic expression of AhTRX h2 in Arabidopsis conferred Al sensitivity as well as premature leaf senescence, manifested by multiple indices, including inhibiting root elongation, severe cell death, and accelerated expression of MC1 and CEX17. AhTRX h2 exhibited similar functions to AtTRX h2, as AhTRX h2 was able to restore the phenotypes of the AtTRX h2 defective mutant (trxh2-4) which showed Al tolerant and late senescence phenotypes. The knock down of AhTRX h2 markedly suppressed Al- and senescence-induced cell death in peanut. AhTRX h2 could recruit catalytic subunit of protein phosphatase 2A (PP2AC2) to form a stable complex. The interaction between AhTRX h2 and AtPP2AC2, as well as AhPP2AC2 and AtTRX h2 was also proved. Overexpression of AhPP2AC2 significantly enhanced Al sensitivity and leaf senescence in Arabidopsis. Protein stability assay revealed that AhTRX h2 was more stable during aging or aluminum stress. Moreover, PP2AC2 could greatly enhance the stability of AhTRX h2 in vivo. Consistent with these observations, overexpression of AhPP2AC2 effectively enhanced AhTRX h2-induced Al sensitivity and precocious leaf senescence. AhTRX h2 and AhPP2AC2 required ABA and ROS in response to cell death under Al stress and senescence, and it was evidence to suggest that ABA acted upstream of ROS in this process. Together, AhTRX h2 and AhPP2AC2 constitute a stable complex that promotes the accumulation of ABA and ROS, effectively regulate cell death. These findings suggest that TRX h2-PP2AC2-mediated pathway may be a widespread mechanism in regulating Al stress and leaf senescence.

Unraveling the Role of the Liriodendron Thioredoxin (TRX) Gene Family in an Abiotic Stress Response

Thioredoxin (TRX) is a small protein with REDOX activity that plays a crucial role in a plant's growth, development, and stress resistance. The TRX family has been extensively studied in Arabidopsis, rice, and wheat, and so it is likely that its members have similar biological functions in Liriodendron that have not been reported in Liriodendron. In this study, we performed the genome-wide identification of the TRX gene family based on the Liriodendron chinense genome, leading to a total of 42 LcTRX gene members. A phylogenetic analysis categorized these 42 LcTRX proteins into 13 subfamilies. We further characterized their chromosome distributions, gene structures, conserved protein motifs, and cis-elements in the promoter regions. In addition, based on the publicly available transcriptome data for Liriodendron hybrid and following RT-qPCR experiments, we explored the expression patterns of LhTRXs to different abiotic stressors, i.e., drought, cold, and heat stress. Notably, we found that several LhTRXs, especially LhTRX-h3, were significantly upregulated in response to abiotic stress. In addition, the subcellular localization assay showed that LhTRX-h3 was mainly distributed in the cytoplasm. Subsequently, we obtained LhTRX-h3 overexpression (OE) and knockout (KO) callus lines in Liriodendron hybrid. Compared to the wild type (WT) and LhTRX-h3-KO callus proliferation of LhTRX-h3-OE lines was significantly enhanced with reduced reactive oxygen species (ROS) accumulation under drought stress. Our findings that LhTRX-h3 is sufficient to improve drought tolerance. and underscore the significance of the TRX gene family in environmental stress responses in Liriodendron.

Analysis of Genetic Diversity in Adzuki Beans (Vigna angularis): Insights into Environmental Adaptation and Early Breeding Strategies for Yield Improvement

Adzuki beans are widely cultivated in East Asia and are one of the earliest domesticated crops. In order to gain a deeper understanding of the genetic diversity and domestication history of adzuki beans, we conducted Genotyping by Sequencing (GBS) analysis on 366 landraces originating from Korea, China, and Japan, resulting in 6586 single-nucleotide polymorphisms (SNPs). Population structure analysis divided these 366 landraces into three subpopulations. These three subpopulations exhibited distinctive distributions, suggesting that they underwent extended domestication processes in their respective regions of origin. Phenotypic variance analysis of the three subpopulations indicated that the Korean-domesticated subpopulation exhibited significantly higher 100-seed weights, the Japanese-domesticated subpopulation showed significantly higher numbers of grains per pod, and the Chinese-domesticated subpopulation displayed significantly higher numbers of pods per plant. We speculate that these differences in yield-related traits may be attributed to varying emphases placed by early breeders in these regions on the selection of traits related to yield. A large number of genes related to biotic/abiotic stress resistance and defense were found in most quantitative trait locus (QTL) for yield-related traits using genome-wide association studies (GWAS). Genomic sliding window analysis of Tajima's D and a genetic differentiation coefficient (Fst) revealed distinct domestication selection signatures and genotype variations on these QTLs within each subpopulation. These findings indicate that each subpopulation would have been subjected to varied biotic/abiotic stress events in different origins, of which these stress events have caused balancing selection differences in the QTL of each subpopulation. In these balancing selections, plants tend to select genotypes with strong resistance under biotic/abiotic stress, but reduce the frequency of high-yield genotypes to varying degrees. These biotic/abiotic stressors impact crop yield and may even lead to selection purging, resulting in the loss of several high-yielding genotypes among landraces. However, this also fuels the flow of crop germplasms. Overall, balancing selection appears to have a more significant impact on the three yield-related traits compared to breeder-driven domestication selection. These findings are crucial for understanding the impact of domestication selection history on landraces and yield-related traits, aiding in the improvement of adzuki bean varieties.

The DREB transcription factor, a biomacromolecule, responds to abiotic stress by regulating the expression of stress-related genes

Abiotic stress is a crucial factor that affects plant survival and growth and even leads to plant death in severe cases. Transcription factors can enhance the ability of plants to fight against various stresses by controlling the expression of downstream genes. The dehydration response element binding protein (DREB) is the most extensive subfamily of AP2/ERF transcription factors involved in abiotic stress. However, insufficient research on the signal network of DREB transcription factors has limited plant growth and reproduction. Furthermore, field planting of DREB transcription factors and their roles under multiple stress also require extensive research. Previous reports on DREB transcription factors have focused on the regulation of DREB expression and its roles in plant abiotic stress. In recent years, there has been new progress in DREB transcription factors. Here, the structure and classification, evolution and regulation, role in abiotic stress, and application in crops of DREB transcription factors were reviewed. And this paper highlighted the evolution of DREB1/CBF, as well as the regulation of DREB transcription factors under the participation of plant hormone signals and the roles of subgroups in abiotic stress. In the future, it will lay a solid foundation for further study of DREB transcription factors and pave the way for the cultivation of resistant plants.

Abiotic Stress in Crop Production

The vast majority of agricultural land undergoes abiotic stress that can significantly reduce agricultural yields. Understanding the mechanisms of plant defenses against stresses and putting this knowledge into practice is, therefore, an integral part of sustainable agriculture. In this review, we focus on current findings in plant resistance to four cardinal abiotic stressors—drought, heat, salinity, and low temperatures. Apart from the description of the newly discovered mechanisms of signaling and resistance to abiotic stress, this review also focuses on the importance of primary and secondary metabolites, including carbohydrates, amino acids, phenolics, and phytohormones. A meta-analysis of transcriptomic studies concerning the model plant Arabidopsis demonstrates the long-observed phenomenon that abiotic stressors induce different signals and effects at the level of gene expression, but genes whose regulation is similar under most stressors can still be traced. The analysis further reveals the transcriptional modulation of Golgi-targeted proteins in response to heat stress. Our analysis also highlights several genes that are similarly regulated under all stress conditions. These genes support the central role of phytohormones in the abiotic stress response, and the importance of some of these in plant resistance has not yet been studied. Finally, this review provides information about the response to abiotic stress in major European crop plants—wheat, sugar beet, maize, potatoes, barley, sunflowers, grapes, rapeseed, tomatoes, and apples.