Abstract
Tea (Camellia sinensis) is one of the most important cash crops in the world. Theanine, as an important amino acid component in tea, is a key quality index for excellent tea quality and high economic value. People increase theanine accumulation in tea mainly through the application of nitrogen fertilizer, shading and pruning. However, these methods are not effective. In this study, we treated tea buds with a 100 μM solution of GA3 containing 1‰ tween-20, investigated the effects of GA3 on theanine accumulation, bud yield, chlorophyll fluorescence parameters and expression level of theanine biosynthesis pathway genes in tea plant by qPCR, LC-MS/MS etc. Results showed that change trends of theanine and GA3 was extremely positively correlated with each other. Exogenous GA3 upregulated the expression level of theanine biosynthesis pathway genes, caused an increase of theanine content (mg·g-1) by 27% in tea leaves compared with Mock, and accelerated the germination of buds and elongation of shoots, which lead to a significant increase of tea yield by 56% (w/w). Moreover, the decrease of chlorophyll contents, photochemical quenching coefficient (qP) and relative electron transport rate (rETR) under GA3 treatment suggested that GA3 reduced photosynthesis in the tender tea leaves, indicating that the decline of carbon assimilation in tea plants was conducive to the nitrogen metabolism, and it was beneficial to the accumulation of theanine. This study provided a new technical and theoretical support for the precise control of tea quality components and phenophase.
Highlights
Humans have consumed tea (Camellia sinensis (L.) Kuntze) as daily necessities for thousands of years, because of the health-promoting functions [1,2,3,4]
Our work showed that GA3 treatment reduced the photochemical quenching and relative electron transport rate both in tender leaves and mature leaves (Figure 6b,c), which supported that the decline of carbon assimilation in tea plants was conducive to the nitrogen assimilation, and it was beneficial to the synthesis and accumulation of the intermediate products such as theanine and other nitrogen metabolites (Figure 3, Table S3) [22]
We investigated the possible correlation between gibberellin and theanine and the effects of GA3 on theanine accumulation
Summary
Humans have consumed tea (Camellia sinensis (L.) Kuntze) as daily necessities for thousands of years, because of the health-promoting functions [1,2,3,4]. The consuming tea categories were mainly composed of the green tea, black tea, white tea, dark tea, yellow tea and oolong tea according to the tea processing method. The consumption of green tea is the second largest tea category after black tea that reaches. Compared with other tea categories, green tea is rich in theanine, the content of theanine in green tea has gained more concern. HJ1, with higher NUE, higher levels of amino acids and higher leaf yield compared with Fudingdabaicha (a common tea cultivar used as control), is native to a relatively isolated natural environment in the Wuling mountains of Western
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