Comparison of cell wall metabolism in the pulp of three cultivars of Nanfeng' tangerine differing in mastication trait

BACKGROUND: Like sweet orange (Citrus sinensis), tangerine (Citrus reticulata) is another citrus crop grown widely throughout the world. However, whether it shares a common mechanism with sweet orange in forming a given mastication trait is still unclear. In this study, three Nanfeng tangerine cultivars, Yangxiao-26 (YX-26) with inferior mastication trait, elite YX-26 with moderate mastication trait and Miguang (MG) with superior mastication trait, were selected to investigate the formation mechanism of mastication trait. RESULTS: 'MG' had the lowest contents of total pectin, protopectin and lignin and the highest gene expression levels of citrus polygalacturonase (PG) and pectin methylesterase (PME) at the end of fruit ripening, whereas 'YX-26' had the lowest water-soluble pectin (WSP) content, the highest lignin content and the lowest PG and PME expression levels. The contents of cellulose and hemicellulose were similar among the three tangerines. CONCLUSION: The fruit mastication trait of C. reticulata was determined by the proportions of WSP and protopectin as well as lignin content, not by cellulose and hemicellulose contents. Pectin content could be a major contribution to the feeling of mastication trait, while PG and PME exhibited an important role in forming a given mastication trait according to the present results as well as previous results for C. sinensis. (C) 2011 Society of Chemical Industry