The CsHSFA-CsJAZ6 module mediated high temperature regulates flavonoid
metabolism in Camellia sinensis
Abstract
High temperatures (HT) seriously affect the yield and quality of tea.
Catechins, derived from the flavonoid pathway, are characteristic
compounds that contribute to the flavor of tea leaves. In this study, we
first showed that the flavonoid content of tea leaves was significantly
reduced under HT conditions via metabolic profiles; and then
demonstrated that two transcription factors, CsHSFA1b and CsHSFA2 were
activated by HT and negatively regulate flavonoid biosynthesis during HT
treatment. Jasmonate (JA), a defensive hormone, plays a key role in
plant adaption to environmental stress. However, little has been
reported on its involvement in HT response in tea. Herein, we
demonstrated that CsHSFA1b and CsHSFA2 activate CsJAZ6 expression
through directly binding to HSE elements in its promoter, and thereby
repress the JA pathway. Most secondary metabolites are regulated by JA,
including catechin in tea. Our study reported that CsJAZ6 directly
interacts with CsEGL3 and CsTTG1 and thereby reduces catechin
accumulation. From this, we proposed a CsHSFA-CsJAZ6 mediated HT
regulation model of catechin biosynthesis. We also determined that
negative regulation of the JA pathway by CsHSFAs and its
homologues is conserved in Arabidopsis. These findings broaden
the applicability of the regulation of JAZ by HSF transcription factors
and further suggest the JA pathway as a valuable candidate for
HT-resistant breeding and cultivation.