Abstract: Tea plants are known to hyperaccumulate fluorine, with significant variation in fluorine accumulation among different cultivars. To explore the patterns of fluorine accumulation in tea leaf cell walls, the fluorine content in leaves of 15 tea cultivars was measured. Moreover, the contents of pectin, hemicellulose, cellulose components, and their respective fluorine contents were analyzed. The distribution of fluorine in the cell walls at different maturity stages of leaves were examined. The results indicate that pectin is a crucial component reflecting the differences in fluoride accumulation and maturity level of the cell walls among cultivars. Only the mature leaves of ‘Liancha 7', ‘Zhuyeqi' and ‘Shangmeizhouzhong' increased pectin content and fluoride content in pectin compared to the young leaves. ‘Tieguanyin' was the only cultivar with the fluoride content in pectin decreased in the mature leaves compared to the young leaves. Correlation analysis of the fluoride proportion in the cell wall components reveals that higher fluoride content in the leaves correlates with greater maturity, reflecting a trend of multi-component fluoride accumulation in the cell walls. Through a comprehensive evaluation and cluster analysis, ‘Hanlü' exhibits consistently high levels of fluorine accumulation in cell walls at different maturity stages (D_1-4=0.704 6, D_5-8=0.928 6). ‘Fuding Dabaicha', ‘Xiangbolü', ‘Xiangbolü 2', ‘Biyun', and ‘Qianmei 702' show moderate levels of fluorine enrichment in cell walls (D_1-4=0.3267-0.4861, D_5-8=0.484 4~0.699 3), while ‘Yunnan Wuheidaye' and ‘Zhuyeqi' exhibit low levels of fluorine accumulation (D_1-4=0.146 5-0.268 8, D_5-8=0.2223-0.345 7). This study explored the regularity and difference of fluorine accumulation in tea cell walls from the perspectives of cultivar and leaf maturity, and provided insights for molecular breeding of low-fluorine tea cultivars.

Key words: tea cultivar, fluorine, leaf cell wall, maturity