Integrated proteomics and transcriptome analysis reveal a decreased catechins metabolism in variegated tea leaves

Abstract

Globally, tea plant (Camellia sinensis (L.) O. Kuntze) is a crucial commercial crop. In this study, a variegated tea plant identified in Huangshan, China. The variegated and residual normal leaves were used as the research material. The variegated leaves of the plant were ecologically insensitive. The components, tissue structure, gene expression patterns, and protein expression profiles of the variegated tea plant were analyzed. Ultrastructural analysis of the variegated leaves revealed that the chloroplasts of the leaves were abnormally developed, with no obvious thylakoids. Compared with normal leaves, the albino leaves had lower total catechins content and higher total free amino acid content. Through RNA sequencing and proteomic analysis, chlorophyll biosynthesis and degradation, photosynthesis, chloroplast development, and flavonoid biosynthesis of the variegated leaves were affected. The less chlorophyll content in the variegated tea leaves could probably attributed to the destruction of chloroplast structure. Besides, the relatively high expression and enzyme activity of CLH, showed an active chlorophyll degradation; the lower expression of Lhcb1, Lhcb3; and POR in chlorophyll synthesis, might be related to the low chlorophyll in variegated leaves. In terms of flavonoid biosynthesis, expression of the related genes was down-regulated and the target protein content of ANR, CHI) was also reduced. These results may provide insight into the catechins mechanism of such variegated phenotypes.