Long-term heat stress induces transcriptomic reprogramming of hormone signaling and metabolic pathways during rapeseed flowering.

Rapeseed is an important edible oil crop that is cultivated in temperate regions worldwide. Rapeseed is a heat-sensitive crop in the pre- and post-flowering stages; however, in the face of global climate change and rising global temperatures, it poses a great challenge to productivity. It is pivotal to determine the dynamics of the rapeseed response to long-term heat stress, particularly during flowering, to accelerate research on heat tolerance in rapeseed. The present study investigated transcriptomic alterations in rapeseed plants subjected to continuous heat stress (33 °C) from the pre-flowering phase to the onset of blooming. Heat stress leads to pronounced phenotypic abnormalities, including the development of smaller flowers, nonviable pollen, and impaired pistil receptivity. Of the 11,582 differentially expressed genes (DEGs), 5,588 were significantly upregulated and 5,994 were downregulated. KEGG enrichment analysis revealed that the differentially expressed genes were associated with hormone signal transduction pathways, energy metabolism (starch and sucrose metabolism, and glutathione metabolism), and plant-specific MAPK signaling pathways. In contrast, genes functioning as ROS scavengers and heat shock transcription factors were also significantly expressed under heat stress. This study provides preliminary insights into the mechanisms underlying heat tolerance in rapeseed and is of great significance for breeding heat-tolerant rapeseed varieties through genetic improvement.