Differential accumulation of specialized metabolite L-theanine in green and albino-induced yellow tea (Camellia sinensis) leaves

L-Theanine is a specialized metabolite in tea (Camellia sinensis) leaves that contributes to tea function and quality. Yellow tea leaves (albino) generally have higher L-theanine contents than green tea leaves (normal), but the reason is unknown. The objective of this study was to investigate why L-theanine is accumulated in yellow tea leaves. We compared original normal leaves (green) and light-sensitive albino leaves (yellow) of cv. Yinghong No. 9. The L-theanine content was significantly higher in yellow leaves than in green leaves (p <= 0.01). After supplementation with [H-2(5)]-L-theanine, yellow leaves catabolized less [H-2(5)]-L-theanine than green leaves (p <= 0.05). Furthermore, most plants contained the enzyme catalyzing L-theanine conversion to ethylamine and L-glutamic acid. In conclusion, L-theanine accumulation in albino-induced yellow tea leaves was due to weak L-theanine catabolism. The differential accumulation mechanism differed from the L-theanine accumulation mechanism in tea and other plants.