Effect of mechanical stress on expression of PAL, C۴H and F۳H genes in tea leaf (Camellia sinensis)

Background and Aim: Tea is one of the most popular beverages in Iran and an economically important commodity in the world that has received much attention from people around the world for its health benefits. Catechins are a group of phenolic compounds that have many effects on human health and play important antimicrobial roles in the body. In addition, these compounds have antioxidant properties to prevent cardiovascular disease and cancer.Methods: Catechins are mainly produced by the naringenin-chalcone → naringenin → dihydrokaempferol pathway. Several enzymes including Phenylalanine ammonia-lyase (PAL), Cinnamate ۴-hydroxylase (C۴H) and Flavanone ۳-hydroxylase (F۳H) are involved in the biosynthesis pathway of these compounds. In this study, the effect of mechanical stress of strong water spraying as a stimulant on the expression of PAL, C۴H and F۳H genes at five times (۰, ۲۴, ۴۸, ۷۲, ۱۲۰ and ۱۶۸ hours) on tea leaf was investigated using qRT-PCR. These three genes play important roles in the production of secondary metabolites, including catechin, which is one of the most important phenolic compounds.Results: The results of analysis of variance showed that mechanical stress caused by severe water shock on tea shrubs had a significant effect on the relative expression of PAL, C۴H and F۳H genes (P<۰.۰۵). Relative expression of PAL and F۳H genes at ۷۲ hours and expression of C۴H gene at ۴۸ hours after treatment were significantly higher than control (around ۴.۵ fold).Conclusion: It can be concluded that the effect of spraying water and causing a mechanical stress as a stimulus on the expression of PAL, C۴H and F۳H genes was positive and expression of genes increased compared to control, which may lead to an increase in beneficial phenolic compounds such as catechins in tea leaves.

Keywords:

Tea , Secondary metabolites , Phenolic compounds , Catechin , Elicitors