Transcriptional Regulation of Photomorphogenesis in Brassica Napus Under Different Light Quality

Abstract

Background: Plants undergo skotomorphogenesis or photomorphogenesis upon the absence or presence of light. Although the light signaling pathway has been well documented in Arabidopsis, relatively little is known in other plant species including Brassica napus.Results: In this study, we examined the response of hypocotyl elongation to different light quality (white, blue, red and far-red light) in B. napus. The result showed each of tested light quality promoted photomorphogenesis, with less effect of red light than blue/far-red light. Subsequently, RNA-sequencing was performed to obtain the transcriptomic profile in B. napus in response to dark and different light quality. A total of 9748 genes were differentially expressed among treatments. Correlation analysis and hierarchical cluster analysis of differentially expressed genes (DEGs) indicated the transcriptomic profile in red light exhibited an analogous pattern with that in dark to some extent, while blue/far-red light induced transcriptional profiles showed distinct patterns. Moreover, we found the differential expressions of PHYB, COP1 and BBXs homologs between two subgenomes, which may affect their interactions with up/downstream pathway. Finally, we constructed a transcriptional network including light signaling, phytohormone and cell elongation/modification, which explained the observed hypocotyl phenotype under different light quality.Conclusions: We partially explained why red light has reduced effect on photomorphogenesis in B. napus by RNA-seq and displayed gene expression of the key regulators in light signaling pathway and their contribution to photomorphogenesis under different light quality in B. napus. The result could improve new sight into understanding on transcriptional regulation of photomorphogenesis of B. napus.