State Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, P.R. China.
J Sci Food Agric. 2010 Jul;90(9):1479-84. doi: 10.1002/jsfa.3970.
FJ72-1 navel orange and its bud mutant FJWC exhibit differences in melting texture character which are influenced mostly by cell wall metabolism. Here we compared the contents of water soluble pectin (WSP), protopectin, total pectin (TP), cellulose, and hemicellulose, activities of polygalaturonase (PG), pectin methylesterase (PME), pectate lyases (PL), cellulase (Cel) and gene expression levels of PG, PME, PL and Cel between the two cultivars.
The content of cellulose and hemicellulose decreased progressively during fruit ripening. At the harvest time (230 DAF), the content of cellulose and hemicellulose in FJWC were obviously higher than those in FJ72-1; the WSP content, PG activities and its gene expression level in FJWC was lower than those in FJ72-1. Moreover, gene expression levels of PME and Cel in FJWC were only one-quarter of those in FJ72-1 at 230 DAF.
The present work showed that the inferior melting character of FJWC attributed to the lower WSP, higher TP or protopectins, higher cellulose and hemicellulose than those in the pulp of FJ72-1 at harvest time. Lower expression levels of PG, PME and Cel at harvest time might be associated with the inferior melting character.
丰水脐橙及其芽变株系 FJWC 在融解质地特性上存在差异，这种差异主要受细胞壁代谢的影响。在这里，我们比较了这两个品种在果实成熟过程中水溶性果胶（WSP）、原果胶、总果胶（TP）、纤维素和半纤维素的含量、多聚半乳糖醛酸酶（PG）、果胶甲酯酶（PME）、果胶裂解酶（PL）、纤维素酶（Cel）的活性以及 PG、PME、PL 和 Cel 基因的表达水平。
纤维素和半纤维素的含量在果实成熟过程中逐渐下降。在收获期（230 DAF），FJWC 的纤维素和半纤维素含量明显高于 FJ72-1；FJWC 的 WSP 含量、PG 活性及其基因表达水平均低于 FJ72-1。此外，在 230 DAF 时，FJWC 的 PME 和 Cel 基因的表达水平仅为 FJ72-1 的四分之一。
本研究表明，FJWC 较差的融解特性归因于收获期时 WSP 含量较低、TP 或原果胶含量较高、纤维素和半纤维素含量较高，而 FJ72-1 果肉中则较低。收获期 PG、PME 和 Cel 的低表达水平可能与较差的融解特性有关。
