A proposed model for CsMYB73 negatively regulating the accumulation of theanine mediated by CsGGT2 and CsGGT4 in tea shoots of ‘Huangkui’ returning green from yellow. (IMAGE)
Caption
A proposed model for CsMYB73 negatively regulating the accumulation of theanine mediated by CsGGT2 and CsGGT4 in tea shoots of ‘Huangkui’ returning green from yellow. The blue arrows indicate theanine metabolism involved in CsGGT2. The orange arrows indicate the theanine metabolism involved in CsGGT4. The black arrows represent upregulated and downregulated gene expression and theanine content. The gray arrows represent a positive effect, and the gray vertical lines represent an inhibitory effect. Glu, glutamine; CsGGT2 and CsGGT4, γ-glutamyl-transpeptidase from tea plants; CsMYB73, transcription factor from tea plants. Ellipses embedded with question marks represent unverified regulatory factors that may participate in this model. During the yellowing period of ‘Huangkui’ leaves, a significant suppression of CsMYB73 further inhibited the theanine hydrolase CsGGT2 activity, and activated the theanine synthase CsGGT4 activity, resulting in a higher level of theanine accumulated in tea shoots. As tea shoots transition from yellow to green, the upregulation of CsMYB73 leads to an enhancement in the activity of theanine hydrolase CsGGT2, while simultaneously suppressing the synthesis of theanine by the theanine synthase CsGGT4. Consequently, this process culminates in a persistent reduction in the accumulation level of theanine in ‘Huangkui’ shoots.
Credit
Horticulture Research
Usage Restrictions
Credit must be given to the creator.
License
CC BY