Differential metabolic profiles of pigment constituents affecting leaf color in different albino tea resources

Albino tea cultivars with distinct leaf colors have rarely been used to explore the metabolic mechanism of leaf color formation. Carotenoids and chlorophyll are primary pigments affecting leaf color with differential metabolic mechanisms in albino tea resources. TEM analysis showed that in albino stage, much less chloroplasts with abnormal structure were observed in white and yellow tea leaves, which corresponded to the significant reduction of total chlorophyll, Chl a and Chl b, and increase of Chl a/b, resulting in tea leaves to lose their green color. Compared to green tea 'Fudingdabaicha' (FD), three albino tea cultivars had higher number of carotenoids, but much lower contents. For albino mutants, significant lower α-Carotene, α-cryptoxanthin and lutein involved in lutein biosynthesis and remarkable higher zeaxanthin (P < 0.05) were responsible for the leaf yellowing of 'Huangjinya' (HJY), while zeaxanthin degradation and accumulation of antheraxanthin, violaxanthin and neoxanthin contribute to the white appearance of 'Jibai' (JB).