YAN Huiting, WANG Yanyan, LU Jianwei, RAO Zilei, LI Yuanyuan, CHANG Runrun, ZHAO Hongyan, YANG Juncong, ZHANG Lilan, BAI Bapu, LU Liping, BAI Bing, WANG Baijuan, GAO Jun, LIU Zhiwei
Camellia sinensis var. pubilimba ‘Mayu’ is a dominant tea cultivar in Lüchun County, Yunnan. This study systematically analyzed the leaf anatomical structures and biochemical components of 28 germplasms using C. sinensis var. sinensis (CSS) and C. sinensis var. assamica (CSA) as controls. This study established a comprehensive evaluation system for germplasm resources for the first time. Key findings include: (1) M4 and M5 in the ‘Mayu’ tea group (MY) exhibits higher stomatal density than the controls, with a 30.0% and 10.6% reduction in stomatal area relative to CSS and CSA, respectively. The MY group exhibits unique undulated wax layers in the upper epidermis. (2) Cold resistance evaluation via membership function analysis identifies M4 and M5 germplasms with the highest scores (0.975 and 0.689), while the palisade-to-spongy tissue ratio shows a significant positive influence on the cold resistance (β=0.179, P<0.01). (3) Biochemical profiling reveals high stability in ‘Mayu’ tea’s water extracts (46.8%) and tea polyphenols (32.14%) (coefficient of variation, CV<5%). Its phenolic-to-amino acid ratio (9.05-14.54) indicates suitability for both black and green tea processing. The catechin quality index of ‘Mayu’ tea significantly surpassed controls (P<0.05), with bitter amino acids reduced by 18.04% compared to CSS and umami amino acids increased by 17.76% relative to CSA. While sweet amino acids show no significant inter-varietal differences. (4) Ten characteristic markers (including methionine, theanine, caffeine, and seven catechin derivatives) were identified through principal component analysis combined with differential metabolite screening, enabling discrimination of ‘Mayu’ tea from controls. This study elucidated the germplasm specificity of ‘Mayu’ tea from structural adaptation and biochemical perspectives, providing a theoretical foundation for its conservation, breeding, and functional component development.