FeCl3-Promoted Photocatalytic Cleavage of Cα-Cß Bond in Lignin and Lignin Model to Benzoic Acid.

Because of the complex structure and inherent inert chemical activity of lignin, it is still challenging to depolymerize lignin to obtain valuable chemicals efficiently. Here, we present an FeCl3-promoted photocatalytic depolymerization strategy to realize the Cα-Cß oxidative cleavage of lignin model compounds at room temperature. The method generates benzoic acid and phenol compounds in high yields. In addition, the method is effective for the depolymerization of organosolv lignin by cleavage of the products of Cα-Cß bonds and affords the corresponding products. This strategy provides a method of using an economical photocatalyst to depolymerize lignin and provides a reference for the industrial depolymerization of lignin.

Effects of different light intensity on leaf color changes in a Chinese cabbage yellow cotyledon mutant.

Leaf color is one of the most important phenotypic features in horticultural crops and directly related to the contents of photosynthetic pigments. Most leaf color mutants are determined by the altered chlorophyll or carotenoid, which can be affected by light quality and intensity. Our previous study obtained a Chinese cabbage yellow cotyledon mutant that exhibited obvious yellow phenotypes in the cotyledons and the new leaves. However, the underlying mechanisms in the formation of yellow cotyledons and leaves remain unclear. In this study, the Chinese cabbage yellow cotyledon mutant 19YC-2 exhibited obvious difference in leaf color and abnormal chloroplast ultrastructure compared to the normal green cotyledon line 19GC-2. Remarkably, low-intensity light treatment caused turn-green leaves and a significant decrease in carotenoid content in 19YC-2. RNA-seq analysis revealed that the pathways of photosynthesis antenna proteins and carotenoid biosynthesis were significantly enriched during the process of leaf color changes, and many differentially expressed genes related to the two pathways were identified to respond to different light intensities. Remarkably, BrPDS and BrLCYE genes related to carotenoid biosynthesis showed significantly higher expression in 19YC-2 than that in 19GC-2, which was positively related to the higher carotenoid content in 19YC-2. In addition, several differentially expressed transcription factors were also identified and highly correlated to the changes in carotenoid content, suggesting that they may participate in the regulatory pathway of carotenoid biosynthesis. These findings provide insights into the molecular mechanisms of leaf color changes in yellow cotyledon mutant 19YC-2 of Chinese cabbage.