The role of Arabidopsis thaliana RASD1 gene in ABA-dependent abiotic stress response

A Large-Scale Genomic Association Analysis Identifies the Candidate Genes Regulating Salt Tolerance in Cucumber (Cucumis sativus L.) Seedlings

Salt stress seriously restricts plant growth and development, affects yield and quality, and thus becomes an urgent problem to be solved in cucumber stress resistance breeding. Mining salt tolerance genes and exploring the molecular mechanism of salt tolerance could accelerate the breeding of cucumber germplasm with excellent salt stress tolerance. In this study, 220 cucumber core accessions were used for Genome-Wide Association Studies (GWAS) and the identification of salt tolerance genes. The salinity injury index that was collected in two years showed significant differences among the core germplasm. A total of seven loci that were associated with salt tolerance in cucumber seedlings were repeatedly detected, which were located on Chr.2 (gST2.1), Chr.3 (gST3.1 and gST3.2), Chr.4 (gST4.1 and gST4.2), Chr.5 (gST5.1), and Chr.6 (gST6.1). Within these loci, 62 genes were analyzed, and 5 candidate genes (CsaV3_2G035120, CsaV3_3G023710, CsaV3_4G033150, CsaV3_5G023530, and CsaV3_6G009810) were predicted via the functional annotation of Arabidopsis homologous genes, haplotype of extreme salt-tolerant accessions, and qRT-PCR. These results provide a guide for further research on salt tolerance genes and molecular mechanisms of cucumber seedlings.

Genetic dissection of drought resistance based on root traits at the bud stage in common bean

A whole-genome resequencing-derived SNP dataset used for genome-wide association analysis revealed 196 loci significantly associated with drought stress based on root traits. Candidate genes identified in the regions of these loci include homologs of known drought resistance genes in A. thaliana. Drought is the main abiotic constraint of the production of common bean. Improved adaptation to drought environments has become a main goal of crop breeding due to the increasing scarcity of water that will occur in the future. The overall objective of our study was to identify genomic regions associated with drought resistance based on root traits using genome-wide association analysis. A natural population of 438 common bean accessions was evaluated for root traits: root surface area, root average diameter, root volume, total root length, taproot length, lateral root number, root dry weight, lateral root length, special root weight/length, using seed germination pouches under drought conditions and in well-watered environments. The coefficient of variation ranged from 11.24% (root average diameter) to 38.19% (root dry weight) in the well-watered environment and from 9.61% (root average diameter) to 39.05% (lateral root length) under drought stress. A whole-genome resequencing-derived SNP dataset revealed 196 loci containing 230 candidate SNPs associated with drought resistance. Seventeen candidate SNPs were simultaneously associated with more than two traits. Forty-one loci were simultaneously associated with more than two traits, and eleven loci were colocated with loci previously reported to be related to drought resistance. Candidate genes of the associated loci included the ABA-responsive element-binding protein family, MYB, NAC, the protein kinase superfamily, etc. These results revealed promising alleles linked to drought resistance or root traits, providing insights into the genetic basis of drought resistance and roots, which will be useful for common bean improvement.

Control of rice pre-harvest sprouting by glutaredoxin-mediated abscisic acid signaling

Pre-harvest sprouting (PHS) is one of the major problems in cereal production worldwide, which causes significant losses of both yield and quality; however, the molecular mechanism underlying PHS remains largely unknown. Here, we identified a dominant PHS mutant phs9-D. The corresponding gene PHS9 encodes a higher plant unique CC-type glutaredoxin and is specifically expressed in the embryo at the late embryogenesis stage, implying that PHS9 plays some roles in the late stage of seed development. Yeast two-hybrid screening showed that PHS9 could interact with OsGAP, which is an interaction partner of the abscicic acid (ABA) receptor OsRCAR1. PHS9- or OsGAP overexpression plants showed reduced ABA sensitivity in seed germination, whereas PHS9 or OsGAP knock-out mutant plants showed increased ABA sensitivity in seed germination, suggesting that PHS9 and OsGAP acted as negative regulators in ABA signaling during seed germination. Interestingly, the germination of PHS9 and OsGAP overexpression or knock-out plant seeds was weakly promoted by H₂ O₂ , implying that PHS9 and OsGAP could affect reactive oxygen species (ROS) signaling during seed germination. These results indicate that PHS9 plays an important role in the regulation of rice PHS through the integration of ROS signaling and ABA signaling.