CsRVE1 promotes seasonal greening of albino Camellia sinensis cv. Huangkui by activating chlorophyll biosynthesis

Abstract

Seasonal greening is a crucial survival strategy for albino tea cultivars, during which dysfunctional chloroplasts recover and chlorophyll biosynthesis increases in albino leaves. However, the regulatory mechanisms of seasonal greening in albino tea plants remain unclear. Here, we report that CsRVE1, a nuclear-located Myb-like transcription factor, can positively modulate the seasonal greening of albino Camellia sinensis cv. Huangkui leaves by activating the expression of genes involved in light harvesting and chlorophyll biosynthesis. The transcriptional expression of CsRVE1 increased during seasonal greening and was tightly correlated with increases in the expression of genes involved in light harvesting (CsLhcb) and chlorophyll biosynthesis (CsCHLH, CsHEMA1 and CsCAO). In vivo and in vitro molecular analyses showed that CsRVE1 can directly bind to the promoters of CsLhcb, CsCHLH and CsPORA, eventually leading to chlorophyll accumulation in tea leaves. Furthermore, transient suppression of CsRVE1 in tea leaves led to a decrease in target gene expression. In contrast, the overexpression of CsRVE1 in Arabidopsis led to chlorophyll increases and the activation of AtLhcb, AtPORA, AtCHLH, etc. These results identify CsRVE1 as an important promoter of seasonal greening that functions by regulating genes involved in chlorophyll biosynthesis in albino tea plants and shed new light on the regulatory mechanisms of leaf phenotypes in plants.

Keywords: Camellia sinensis; REVEILLE 1; albino; chlorophyll biosynthesis; seasonal greening.