Comparative Transcriptome Analysis Reveals Differential Mechanisms of Soft Rot Resistance in Lettuce Grown Under White and Blue Light

ABSTRACT

Specific light wavelengths can affect plant responses to pathogens. In this study, we investigated the soft rot resistance of lettuce grown under different light conditions and analyzed the underlying molecular mechanisms using RNA‐seq data. The results revealed that blue‐light‐grown leaves had a better resistance to soft rot infection compared to the leaves grown under white light and other light conditions, as evidenced by the fewer soft rot symptoms and lower soft rot incidence. After soft rot infection, H₂O₂ levels increased in all samples grown under different light conditions but were the lowest in blue‐light‐grown leaves. Significantly higher activities of superoxide dismutase (SOD) and catalase (CAT) were observed in blue‐light‐grown leaves than in white‐light‐grown regardless of soft rot infection. Transcriptome analysis revealed that blue‐light‐grown leaves could better activate and maintain the expressions of CAT and SOD genes, isochorismate synthase and pathogenesis‐related protein genes, and the genes involved in the ascorbate‐glutathione cycle, the photosynthesis‐related metabolic pathways than white‐light‐grown leaves, which should contribute to the blue‐light‐induced soft rot resistance. In addition, we found many genes involved in the synthesis and signaling pathways of jasmonic acid and ethylene were significantly upregulated in white‐light‐grown leaves after soft rot infection. Thus, light quality in the growth environment can affect lettuce soft rot resistance by altering the antioxidant and photosynthetic systems and plant hormone‐related pathways, providing new ideas for the prevention and control of soft rot in lettuce.