Transcriptome analysis reveals genes expression pattern of seed response to heat stress in Brassica napus L.

Seeds might deteriorate, and lose the ability to germinate when stored under high temperature and high humidity. Brassica napus is one of the most important oil crops in China. However, B. napus seeds were generally stored through summer season with high ambient temperature, which lead to seed viability loss. In order to understand the mechanism of seed response to heat stress and improve seed heat tolerance, B. napus seeds were treated with high temperature(40C) and ultra-high temperature(60C) for 4 h. The germination of heatstressed seeds were obviously slower, the germination index and vigor index decreased with temperature increase from 40 to 60C, and the 40C pretreatment could improve the seed tolerance to 60C heat stress.Transcriptomics results showed that 442 differentially expressed genes(DEGs) were identified in seeds after heat stress. Gene ontology and KEGG pathway enrichment analysis revealed that some of the genes were involved in posttranslational modification, protein turnover, chaperones and carbohydrate transport, metabolic pathways and secondary metabolites biosynthesis pathway. Among these DEGs, sHSP and transcription factors genes were involved in heat stress tolerance. Thirty-two overlapping genes under different high temperature stress(40C and60C) were enriched in biological processes of response to oxidative stress and abiotic stimulus. The expression trends of 12 genes randomly selected from the RNA-seq data were almost consistent with the results of qRT-PCR.Our results revealed several potential candidate genes and pathways related to heat responsive by high temperature, which is beneficial for further improving the heat tolerance in B. napus seeds.