Liu YongZhong, Liu Qing, Xiong JingJing, Deng XiuXin
National Key Laboratory of Crop Genetic Improvement; College of Horticulture and Forestry Science, Huazhong Agricultural University, Wuhan 430070, China.
Sci China C Life Sci. 2007 Aug;50(4):511-7. doi: 10.1007/s11427-007-0063-8.
'Fengjiewancheng' (FW) (Citrus sinensis), a bud sport of 'Fengjie 72-1' navel orange (FJ), ripens one month later than its parental line. Differences in sugar and acid content and the transcript level of sucrose-and citric-metabolic enzymes for the two cultivars were investigated during fruit ripening. Results showed that both sugar and acid metabolisms of the mutant were affected by the mutation. In the pulp of FW, sugar content was significantly lower than that in FJ before 227 DAF (days after flowering) and higher at 263 DAF; the mutant's gene expression of one isoform of citrus sucrose synthase (CitSS1) was delayed, and its gene expression of citrus acid invertase (CitAI) was stronger than that in its parental cultivars at 207 and 263 DAF. In the peel, only the sucrose content in FW was significantly lower than those in FJ at the early periods of fruit ripening (165 and 187 DAF); however the transcripts of the sucrose-cleaving enzymes in the mutant were higher than those in FJ at different ripening points. As regards acid accumulation in the two cultivars, it was observed that in the pulp of the mutant, the malic acid content was significantly lower than that in its parental cultivars from 187 to 263 DAF, and in the peel, remarkably higher during the whole fruit ripening period. The citric acid content in both the pulp and the peel of FW was higher than that in those of FJ during the early ripening period and lower during the late ripening period, which were correspondingly associated in part with the higher transcript level of citrus mitochondrial citrate synthase (CitCS) and with lower or undetectable transcript level of citrus cytosolic aconitase (CitAC). Hence, it could be concluded that the mutation in FW affected sugar and acid metabolism, which might be related with other late-ripening phenotypes.
“凤解晚橙”（FW）（甜橙）是“奉节72 - 1”脐橙（FJ）的一个芽变品种，其成熟时间比亲本晚一个月。研究了这两个品种在果实成熟过程中糖酸含量以及蔗糖和柠檬酸代谢酶转录水平的差异。结果表明，突变体的糖代谢和酸代谢均受到突变的影响。在FW果肉中，花后227天（DAF）之前糖含量显著低于FJ，而在263 DAF时则高于FJ；柑橘蔗糖合酶一种同工型（CitSS1）的基因表达在突变体中延迟，柑橘酸性转化酶（CitAI）的基因表达在207和263 DAF时比其亲本品种更强。在果皮中，仅在果实成熟早期（165和187 DAF）FW中的蔗糖含量显著低于FJ；然而，突变体中蔗糖裂解酶的转录本在不同成熟阶段均高于FJ。关于两个品种的酸积累情况，观察到在突变体果肉中，从187到263 DAF苹果酸含量显著低于其亲本品种，而在果皮中，在整个果实成熟期间显著更高。FW果肉和果皮中的柠檬酸含量在成熟早期高于FJ，在成熟后期低于FJ，这部分相应地与柑橘线粒体柠檬酸合酶（CitCS）较高的转录水平以及柑橘胞质乌头酸酶（CitAC）较低或未检测到的转录水平有关。因此，可以得出结论，FW中的突变影响了糖和酸代谢，这可能与其他晚熟表型有关。
