异花授粉对柚果实代谢产物的影响及其与内裂的关系

为探究异花授粉对柚果实内裂的影响机制,以琯溪蜜柚为父本、早香柚为母本进行异花授粉,统计种子数与果实内裂的关系,并利用气相色谱-质谱技术(GC-MS)分析果实汁胞代谢物组分。结果表明,早香柚自花授粉果实裂瓣数多为2或3瓣,且裂瓣多处于对称位置,说明果实横向生长拉力是中心柱开裂的直接原因;异花授粉后,果实内裂率与种子数有关,低于30粒时内裂率为100%,高于80粒时果实不内裂,大部分异花授粉果实的种子数介于30~80粒之间,内裂率为51.4%,说明异花授粉产生的大量种子可起到保护中心柱的物理性作用;从代谢水平上看,异花授粉后种子可通过激素、多胺等内源物质调控汁胞可溶性糖、有机酸、氨基酸,以及莽草酸途径及其下游次生代谢过程,使果实在外观和风味性状上表现明显的花粉直感效应,其中渗透调节物质的含量变化可能与果实膨大和内裂有关。本研究为进一步探究柚果实内裂调控机制提供了依据。

Effect of Cross-Pollination on Metabolites and Its Relationship With Fruit Inner-Cracking in Pomelo

To study the mechanism of cross-pollination on fruit inner-cracking in pomelo, Zaoxiang pomelo was chosed as female parents and Guanxi pomelo as male parents for hybrididization, and Zaoxiang pomelo self-pollination was chosen as control. The relationship between the seed numbers and inner-cracking ratio was surveyed, and the metabolic changes of juice sacs during the initiation period of inner-cracking were analyzed by metabolomics. The results showed as follows: the numbers of cracked-segments in self-pollination fruits were mostly 2 or 3, and usually located at symmetrical position, which indicated the power of transverse growth may be the direct cause of fruit inner-cracking. After cross-pollination, the fruit inner-cracking ratio was related to the number of seeds. The ratio of inner-cracking was 100% when seeds were less than 30 and 100% when higher than 80 seeds. The seeds numbers of most cross-pollinated fruits were between 30 and 80, at which the inner-cracking ratio was 51.4%, which indicated the plenty of seeds produced by cross-pollination could play a physical role in protecting the center column. According to the metabolome results, the metabolic pathways of the soluble sugars, organic acids, amino acids, and the shikimic acid and its downstream secondary metabolic pathways were regulated by seeds through the endogenous substances such as hormones and polyamine, which resulted in evident xenia effect in both fruit appearance and taste. In the changed processes, osmotic substances may be related to fruit enlargement and further inner-cracking. The study provide a theoretical basis for pomelo inner-cracking mechanism