Analysis of lettuce transcriptome reveals the mechanism of different diel light cycle in promoting the growth and quality

Abstract

Abstract Diel light cycle plays a crucial role in controlling the production and quality of vegetables. However, the mechanism of diel light cycle on vegetable growth and quality is scarce studied. To investigate the impact of light cycle on lettuce growth and quality, we designed three diel scenarios, including 16 hours of light and 8 hours of darkness (1C), 12 hours of light and 6 hours of darkness (1.3C), and 8 hours of light and 4 hours of darkness (2C). Lettuce grew better under the 2C scenariothan under the other light cycle scenarios. Under the 2C scenario, the lettuce leaves exhibited greater enhancements in the levels of soluble protein, soluble sugar, and carotenoid content compared to the other scenarios. By comparing the expression levels under different diel scenarios (1C vs 1.3C, 1C vs 2C, and 1.3C vs 2C), we identified 7,209 differentially expressed genes (DEGs). Additionally, 3 gene modules that were closely related to growth, quality and photosynthesis of lettuce were selected by WGCNA analysis. The eigengenes of three gene modules were enriched in plant hormone signal transduction, sphingolipid metabolism, and nucleocytoplasmic transport pathways. Through network analysis, we identified six hub genes (CIP1, SCL34, ROPGEF1, ACD6, CcmB, and Rps4) in three gene modules, which were dominant in the mechanism by which diel light cycle affected lettuce growth and quality. qRT-PCR analysis confirmed the expression levels of hub genes. This study significantly enhanced our comprehension of the diel light cycle in the growth morphology, nutritional quality, and metabolic pathways of lettuce.