Effect of Supplemental Light for Leaves Development and Seed Oil Content in Brassica napus

Rapeseed is an important commercial crop globally, used for both animal fodder and human consumption. Varied insolation duration and intensity are among the main factors affecting the seed yield and quality of <i>Brassica napus</i> (<i>B. napus</i>) worldwide. In this study, the high-oil-content rapeseed cultivar "Qingyou 3" was subjected to a light supplementation trial during both the vegetative growth period and the seed productive stage. Different light intensity conditions were stimulated using light-emitting diodes (LEDs). The main plot factor was land condition, with LED treatment (Treatment) and without LED treatment (Control) under natural conditions. The results showed that the leaf size and thickness, photosynthesis efficiency, and seed oil content of <i>B. napus</i> increased significantly after light supplementation. Then, 18 cDNA libraries were constructed from leaf segments (30 days after transplanting-DAT) and seeds 30 and 40 days after pollination (DPA) for RNA transcriptome sequencing. It was found that genes encoding lipid transfer protein, phenylpropanoid biosynthesis, photosynthesis, and plant hormone signal transduction were enriched in differentially expressed genes (DEGs). The qRT-PCR analysis showed that eight key genes had significant variations, a finding also consistent with the RNA-seq results. The aim of this study was to identify the DEGs and signaling pathways in the leaves and seeds of <i>B. napus</i> during the vegetative and seed productive stages under different light intensities. The results provide insight into how sufficient light plays a critical role in promoting photosynthesis and serves as the foundation for material accumulation and yield formation.