Comparative Transcriptome Analysis of Two Brassica napus L. Varieties with Different High Planting Tolerance under High Planting Density

Reasonable dense planting is an important way to increase rapeseed yield. To investigate the molecular response of rapeseed to dense planting, this study focused on tolerant and sensitive rapeseed varieties, and transcriptome sequencing was performed on their upper and lower leaves under low and high density planting conditions. After comparative analysis, 840 differentially expressed genes were selected. KEGG analysis showed that these DEGs were enriched in metabolic pathways mainly related to carbon metabolism, amino acid metabolism, and lipid metabolism, indicating differences in the expression of genes related to these metabolic pathways between the two varieties. GO analysis showed that under high-density environments, the DEG in the upper leaves of the tolerant variety was significantly enriched in biological processes such as membrane and membrane components, as well as catalytic activity, while the DEG in the lower leaves was significantly enriched in processes such as redox and stress response. The difference in light environment has different effects on leaves at different positions. Eleven DEGs related to photosynthesis and 24 DEGs related to shade response were screened, including SPL, HD-ZIP transcription factor, YUCCA, UVR8, TCP transcription factor, and photosensitive pigment binding factor. This result is expected to provide important reference for studying the molecular mechanism of rapeseed density tolerance.