Genome-Wide Analysis of the RbcS Gene Family and Expression Analysis Under Light Response in Brassica napus L.

Enhancing photosynthetic efficiency represents a key approach for improving crop biomass, with its translation into higher grain yield being contingent upon the efficiency of photosynthate partitioning toward harvestable organs. The Rubisco small subunit (<i>RbcS</i>) gene family plays an essential role in this process by stabilizing and regulating Rubisco assembly and activity during photosynthesis. In this study, we identified 61 <i>RbcS</i> genes across <i>B</i>. <i>napus</i>, <i>B</i>. <i>juncea</i>, and <i>B</i>. <i>carinata</i>, and their diploid progenitors <i>B</i>. <i>rapa</i>, <i>B</i>. <i>nigra</i>, and <i>B</i>. <i>oleracea</i> by genome-wide screening and bioinformatic approaches. Phylogenetic relationships, gene structures, conserved domains, collinearity, cis-regulatory elements, expression profiles, and haplotype variations were systematically investigated, revealing the potential functional role significance and regulatory complexity of <i>RbcS</i> genes in photosynthesis. The results imply that the promoter type of this gene family may belong to light-inducible promoters. Furthermore, while a haplotype analysis provided valuable insights for selecting germplasm with potentially high photosynthetic efficiency, definitive confirmation of their effects requires functional validation. Collectively, our results establish a theoretical foundation for understanding the molecular mechanisms of <i>BnRbcS</i> genes and propose candidate genetic targets for further exploration to enhance photosynthetic performance in rapeseed breeding.