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 [2H5]-l-theanine, yellow leaves catabolized less [2H5]-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.