Title : Stem-specific protein TSJT1-like (TSJT1) gene regulates growth parameters in rapeseed (Brassica napus L.) under drought stress
Drought is one of the major environmental stress conditions affecting the growth of rapeseed across the globe. Understanding the genetic architecture of drought stress tolerance in rapeseed at the seedling stage is crucial for developing drought-tolerant varieties. In the present study, 119 diverse rapeseed genotypes were evaluated under greenhouse conditions at the seedling stage for Leaf Number (LN), Leaf Area Index (LAI), Seedling Dry Weight (SDW) and Seedling Wet Weight (SWW) under two irrigation regimes (well-watered and drought stress conditions). A Genome-Wide Association Study (GWAS) was carried to identify loci underlaying the traits tested. The panel genotyped using the Infinium Brassica 60K SNP array with 29,311 polymorphic markers. Ninety-one SNPs on 19 chromosomes significantly associated with four growth related traits in the seedling stage, and 40 Candidate Genes (CGs) were screened at the flanking 288 kb region of significant SNPs. Furthermore, several promising SNPs revealed significant differences among haplotypes for LN, LAI, SDW, and SWW under drought stress. Functional annotation of genes revealed important putative CGs underlying the identified stable genomic regions such as protein kinases, transporters, methyltransferases and NAD-dependent dehydratases. To validate the CGs associated with the SNPs, RNA-seq analysis was subsequently performed in leaves of two cultivars with the highest drought tolerance according to phenotypic traits. A total of 10,149 differentially expressed genes (DEGs) were obtained. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes analysis (KEGG) showed up-regulated genes that mainly enriched in the hormone metabolism, signal transductions and photosynthesis-related process. Through the integration of the GWAS and the RNA-sequencing data, 30 CGs were identified. Among the identified CGs, pleiotropic stem-specific protein TSJT1 (LOC106380617) on chromosome C05 was related to LN, LAI, DW and upregulated (45-fold) under drought condition. This gene may play an important role in rapeseed drought response and can be used for further breeding study. Our findings provide new insights into the response mechanisms of rapeseed against drought stress and contribute to further genetic breeding.
What will audience learn from your presentation?
• The current analyses show the power of the GWAS both for identifying putative candidate genes and for improving plant adaptive traits in rapeseed.
• The drought tolerance genotypes can be used as candidate parents to improve drought tolerance in rapeseed.
• Our study provides essential information about significant MTAs related to drought tolerance at seedling stage which can be further used for marker-assisted selection.
• By integrating the results of the GWAS and the common DEGs promising candidate genes were prioritized for further research.