High Light Intensity Triggered Abscisic Acid Biosynthesis Mediates Anthocyanin Accumulation in Young Leaves of Tea Plant (Camellia sinensis)

Abstract

There is increasing interest in the production and consumption of tea (Camellia sinensis L.) processed from purple–leaved cultivar due to their high anthocyanin content and health benefits. However, how and why seasonal changes affect anthocyanin accumulation in young tea leaves still remains obscured. In this study, anthocyanin and abscisic acid (ABA) contents in young leaves of Zifuxing 1 (ZFX1), a cultivar with new shoots turning to purple in Wuyi Mountain, a key tea production region in China, were monitored over four seasons. Young leaves produced in September were highly purplish, which was accompanied with higher anthocyanin and ABA contents. Among the environmental factors, the light intensity in particular was closely correlated with anthocyanin and ABA contents. A shade experiment also indicated that anthocyanin content significantly decreased after 168 h growth under 75% shade, but ABA treatment under the shade conditions sustained anthocyanin content. To confirm the involvement of ABA in the modulation of anthocyanin accumulation, anthocyanin, carotenoids, chlorophyll, ABA, jasmonic acid (JA), and salicylic acid (SA) in the young leaves of four cultivars, including ZFX1, Zijuan (ZJ), wherein leaves are completely purple, Rougui (RG) and Fudingdabaicha (FDDB) wherein leaves are green, were analyzed, and antioxidant activities of the leaf extracts were tested. Results showed that ABA, not other tested hormones, was significantly correlated with anthocyanin accumulation in the purple–leaved cultivars. Cultivars with higher anthocyanin contents exhibited higher antioxidant activities. Subsequently, ZFX1 plants were grown under full sun and treated with ABA and fluridone (Flu), an ABA inhibitor. ABA treatment elevated anthocyanin level but decreased chlorophyll contents. The reverse was true to those treated with Flu. To pursue a better understanding of ABA involvement in anthocyanin accumulation, RNA–Seq was used to analyze transcript differences among ABA– or Flu–treated and untreated ZFX1 plants. Results indicated that the differentially expressed genes in ABA or Flu treatment were mainly ABA signal sensing and metabolism–related genes, anthocyanin accumulation-related genes, light–responsive genes, and key regulatory MYB transcription factors. Taking all the results into account, a model for anthocyanin accumulation in ZFX1 cultivar was proposed: high light intensity caused reactive oxygen stress, which triggered the biosynthesis of ABA; ABA interactions with transcription factors, such as MYB-enhanced anthocyanin biosynthesis limited chlorophyll and carotenoid accumulation; and transport of anthocyanin to vacuoles resulting in the young leaves of ZFX1 with purplish coloration. Further research is warranted to test this model.

Carotenoid Accumulation in the Rhododendron chrysanthum Is Mediated by Abscisic Acid Production Driven by UV-B Stress

“…Conversely, CK2α and CK2β are important modulators of plant circadian rhythms, and ABA treatment significantly reduced the expression of the CK2α-regulating gene, CSNK2A . This observation, however, defies prior research, and it could be explained by the R. chrysanthum ’s distinct ABA-regulating mechanism [ 27 ]. The PSII light-harvesting chloroplast protein complex’s pertinent genes were found to be down-regulated.…”

Effects of Light Intensity on Endogenous Hormones and Key Enzyme Activities of Anthocyanin Synthesis in Blueberry Leaves

“…The GA 4 content was strongly negatively correlated with the anthocyanin content in sweet cherry [32]. There was a strong positive correlation between the ABA content and anthocyanin content in Lycium fruit [33] and purple-leaved cultivars of tea [34]. The IAA content was positively correlated with the anthocyanin content during bicolor leaf development [35].…”

Deciphering the Anthocyanin Metabolism Gene Network in tea plant(Camellia sinensis) through Structural Equation modeling

“…Combined with BLASTP and HMMER, 30 gene families related to anthocyanin metabolism were systematically identi ed from tea genome, including 2110 independent sequences. Among them, PAL (6), C4H (6), 4CL (34), CHS (16), ACC (2), CHI (7), F3H (2), F3'H (1), F3'5'H (4), DFR (60), FLS (3), ANS (2) are responsible for the catalytic reaction of anthocyanin skeleton synthesis. Gene families involved in anthocyanin structural modi cation include UFGT (340), OMT (44), BAHD (181), gene families involved in anthocyanin transport include GST (94), MRP (92), MATE (99), SNARE (40), gene families involved in anthocyanin degradation include PPO (6), PRX (119) and β-glycosidase (25).…”

“…With the development and maturity of purple young leaves of tea trees, the color of tea leaves changes from purple to green [33]. This color change may be of great signi cance to the environmental adaptation of tea plants, but it is not clear what the potential mechanism is [34]. The phenomenon of tea changing from purple to green is closely related to anthocyanin degradation.…”