The R2R3 Transcription Factor CsMYB59 Regulates Polyphenol Oxidase Gene CsPPO1 in Tea Plants (Camellia sinensis)

Abstract

Polyphenol oxidase (PPO) plays a role in stress response, secondary metabolism, and other physiological processes during plant growth and development, and is also a critical enzyme in black tea production. However, the regulatory mechanisms of PPO genes and their activity in tea plants are still unclear. In this study, we measured PPO activity in two different tea cultivars, Taoyuandaye (TYDY) and Bixiangzao (BXZ), which are commonly used to produce black tea and green tea, respectively. The expression pattern of CsPPO1 was assessed and validated via transcriptomics and quantitative polymerase chain reaction in both tea varieties. In addition, we isolated and identified an R2R3-MYB transcription factor CsMYB59 that may regulate CsPPO1 expression. CsMYB59 was found to be a nuclear protein, and its expression in tea leaves was positively correlated with CsPPO1 expression and PPO activity. Transcriptional activity analysis showed that CsMYB59 was a transcriptional activator, and the dual-luciferase assay indicated that CsMYB59 could activate the expression of CsPPO1 in tobacco leaves. In summary, our study demonstrates that CsMYB59 represents a transcriptional activator in tea plants and may mediate the regulation of PPO activity by activating CsPPO1 expression. These findings provide novel insights into the regulatory mechanism of PPO gene in Camellia sinensis, which might help to breed tea cultivars with high PPO activity.

Polysaccharides of Aspergillus cristatus attenuate obesity by regulating gut microbiota and gut microbiota-related metabolites

“…Tea is one of the most widely consumed non-alcoholic beverages around the world [33][34][35][36][37][38][39][40] . In China, Fu-brick tea has historically been used to treat obesity and metabolic disorders [41] .…”

A comprehensive review of polyphenol oxidase in tea (Camellia sinensis): Physiological characteristics, oxidation manufacturing, and biosynthesis of functional constituents

“…Overexpression of the PPO gene family in Camellia sinensis (CsPPOs) has been shown to improve pest disease resistance in tea plants (Gulati et al., 1999; Palanisamy & Mandal, 2014); meanwhile, the laccase gene family in C. sinensis (CsLACs) participates in constitutive lignin biosynthesis throughout tea plant growth and development (Yu et al., 2021). Certain R 2 R 3 ‐MYB transcription factors with high specificity and amplification in tea plants regulate secondary metabolite biosynthesis, such as catechins, and specifically activate the CsPPO 1 gene and enhance PPO activity (Huang et al., 2021; Li et al., 2022). Thus, a better understanding of the regulatory mechanisms governing the expression of PPO genes and their activity in tea plants based on the genomes and transcriptomes of tea plants is needed (Xia et al., 2020), which will contribute to the breeding and selection of high‐PPO‐activity tea cultivar resources.…”

Recent developments in cold plasma‐based enzyme activity (browning, cell wall degradation, and antioxidant) in fruits and vegetables

“…Recent studies have confirmed the role of PPO in EB on various fruits and vegetables, including apple (Murtaza et al., 2019; Xu et al., 2020), banana (Lim et al., 2020), litchi (Ali et al., 2019), dates (Al‐Amrani et al., 2020), pear (Zheng et al., 2019), sweet potato (Lim et al., 2019, 2020), apricot (Derardja et al., 2019), potato (Aksoy & Öztekin, 2021; González et al., 2020), lettuce (Li et al., 2021), and ginger (Lim et al., 2020). In addition, phenylalanine ammonia‐lyase (PAL), a key rate‐limiting enzyme of the phenylalanine pathway, showed a significant role in EB by modulating the production of polyphenols (Huang et al., 2021). Inhibition of PAL using purslane extract significantly reduced EB in fresh‐cut potatoes (Liu et al., 2019).…”

“…Huang et al. (2021) proved that the repression activity and expression of PAL using ethanol and acetic acid as anti‐browning agents for lettuce with discoloration problems. Apart from PPO, PAL activity, and phenolic compounds, various other factors are crucial in the browning reaction.…”