Mechanism Underlying the Shading-Induced Chlorophyll Accumulation in Tea Leaves

Abstract

Besides aroma and taste, the color of dry tea leaves, tea infusion, and infused tea leaves is also an important index for tea quality. Shading can significantly increase the chlorophyll content of tea leaves, leading to enhanced tea leaf coloration. However, the underlying regulatory mechanism remains unclear. In this study, we revealed that the expressions of chlorophyll synthesis genes were significantly induced by shading, specially, the gene encoding protochlorophyllide oxidoreductase (CsPOR). Indoor control experiment showed that decreased light intensity could significantly induce the expression of CsPOR, and thus cause the increase of chlorophyll content. Subsequently, we explored the light signaling pathway transcription factors regulating chlorophyll synthesis, including CsPIFs and CsHY5. Through expression level and subcellular localization analysis, we found that CsPIF3-2, CsPIF7-1, and CsHY5 may be candidate transcriptional regulators. Transcriptional activation experiments proved that CsHY5 inhibits CsPORL-2 transcription. In summary, we concluded that shading might promote the expression of CsPORL-2 by inhibiting the expression of CsHY5, leading to high accumulation of chlorophyll in tea leaves. The results of this study provide insights into the mechanism regulating the improvements to tea plant quality caused by shading.

A point mutation in Chl biosynthesis gene Mg-chelatase I subunit influences on leaf color and metabolism in strawberry

“…Further study showed that shading might increase the expression of CsPORL-2 (encoding protochlorophyllide oxidoreductase) by inhibiting the expression of CsHY5, resulting an increase of chlorophyll in tea leaves (Chen et al, 2021). However, how FveCHLI correlation with low light and accumulation of chlorophyll should be investigated further.…”

“…The same reports were found in tea plants, as albino-leaf plants ‘Huangjinya’ and ‘Anjibaicha’ showed a yellow-leaf phenotype under strong light but green leaf under weak light (Song et al, 2017; Wei et al, 2011). Further study showed that shading might increase the expression of CsPORL-2 (encoding protochlorophyllide oxidoreductase) by inhibiting the expression of CsHY5, resulting an increase of chlorophyll in tea leaves (Chen et al, 2021). However, how FveCHLI correlation with low light and accumulation of chlorophyll should be investigated further.…”

HPLC–MS2 Analysis of Chlorophylls in Green Teas Establishes Differences among Varieties

“…The obtained data regarding the identification of each pigment agree with previous characterizations [ 18 , 19 ], and the analysis was developed using authentic standards. Most of the studies conducted on green tea have been based on chlorophyll a and b content [ 9 , 11 , 20 ], which should be the main chlorophyll pigments. In addition, other analytical studies have also identified dephytylated (chlorophyllide and pheophorbide) and phytylated (pheophytin) chlorophyll derivatives [ 7 , 13 , 21 ].…”

“…The total chlorophyll content obtained is in line with that found in previous studies although our extraction method resulted in slightly more exhaustive findings for all of the studied samples. Previous studies regarding the chlorophyll content in green teas have obtained amounts in the range of 1000 mg/kg [ 8 , 20 ] and up to 4000 mg/kg [ 24 ], while for Matcha samples, the literature describes amounts of up to 15,000 mg/kg [ 10 , 24 ]. In any case, based on the total amount of chlorophylls, two separate groups can be clearly distinguished.…”

Mechanism underlying the carotenoid accumulation in shaded tea leaves

“…Similar to the carotenoid regulation in other plants ( Fu et al, 2019 ), it was demonstrated that light also influences the synthesis and accumulation of tea pigments ( Yue, Wang, & Yang, 2021 ). The shading of commonly grown green tea varieties will lead to the increased intensity of green coloration on leaves ( Chen et al, 2021 ). Sonobe, Miura, Sano, and Horie (2018) used different shading treatments (0%, 35%, 75%, and 90%) and observed that the carotenoid content increases as the degree of shading increases.…”