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Identification and characterization of candidate genes for drought tolerance during the germination stage in Brassica napus L.

Yuan Rong1,**,Du Yuan-Yuan1,**,Hong Mei-Yan1,Gao Jie1,Huang Zhen2,Li Ke-Qi2,*,Zeng Xin-Hua1,*   

  1. 1 Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences / Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture and Rural Affairs, Wuhan 430062, Hubei, China; 2 College of Agronomy, Northwest A&F University / State Key Laboratory of Crop Stress Biology for Arid Areas, Yangling 712100, Shaanxi, China
  • Received:2026-05-08 Revised:2026-08-21 Accepted:2026-08-21 Published:2026-08-31
  • Supported by:
    This study was supported by the Science and Technology Innovation Program of CAAS (CAAS-ASTIP-2021-OCRI) and the China Agriculture Research System of MOF and MARA (CARS-12).

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Abstract: Brassica napus is an important oilseed crop in China. Drought stress significantly inhibits its germination rate and seedling establishment, thereby causing yield loss. To comprehensively identify the genes underlying drought tolerance at the seed germination stage, we simulated drought stress using the PEG-6000 solution and evaluated 183 B. napus accessions for germination-stage drought tolerance. Phenotypic traits including germination rate (GR), germination potential (GP), germination index (GI), seedling percentage (SP), vigor index (VI), shoot fresh weight (SFW), root fresh weight (RFW), and root length (RL) were measured. A genome-wide association study (GWAS) identified nine significant SNP loci and 213 potential candidate genes. Furthermore, transcriptomic analysis of six accessions with contrasting drought tolerance revealed 13,251, 10,250, 10,455, 8968, 9990, and 16,706 differentially expressed genes (DEGs) under 0% and 15% PEG-6000 treatments, respectively. These DEGs were primarily enriched in drought-responsive KEGG pathways such as “plant hormone signal transduction”, “plant-pathogen interaction”, “MAPK signaling pathway-plant”, “phenylpropanoid biosynthesis”, and “starch and sucrose metabolism”. Among them, ZS11A03G038720, ZS11A09G011050, ZS11C02G013040, and ZS11C02G013790 were downregulated following PEG treatment, whereas ZS11A03G039060, ZS11C02G013640, and ZS11C02G013660 were upregulated. By integrating GWAS and RNA-seq data, we identified seven candidate genes associated with drought tolerance during seed germination. This study not only reveals key genetic loci underlying drought tolerance at the germination stage in B. napus, but also provides seven core candidate genes with potential value for molecular breeding of drought-tolerant rapeseed varieties, thereby offering genetic resources and theoretical insights for future improvement strategies.

Key words: Brassica napus, germination stage, drought tolerance, genome-wide association study, transcriptome analysis

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