Lin Yuanxiu, Tang Honglan, Zhao Bing, Lei Diya, Zhou Xuan, Yao Wantian, Fan Jinming, Zhang Yunting, Chen Qing, Wang Yan, Li Mengyao, He Wen, Luo Ya, Wang Xiaorong, Tang Haoru, Zhang Yong
College of Horticulture, Sichuan Agricultural University, Chengdu, China.
Institute of Pomology and Olericulture, Sichuan Agricultural University, Chengdu, China.
Front Plant Sci. 2022 Dec 15;13:1087452. doi: 10.3389/fpls.2022.1087452. eCollection 2022.
Hardy kiwifruit () has an extensive range of nutritional and bioactive compounds and has been valued as a great resource for kiwifruit breeding. A better understanding of the dynamic changes of the composition and accumulation of nutritional compounds during fruit development and ripening is required before genetic or cultural improvements can be targeted.
In the present study, the phytochemical analysis of two cultivars 'Yilv' and 'Lvmi-1' showed that they comprised different morphology, with a higher fruit diameter while a lower vertical fruit diameter of 'Lvmi-1' compared with 'Yilv'. The antioxidant capacity of both cultivars decreased during the maturity time and showed no significant difference between them. Furthermore, although glucose gradually increased during the maturity time, the predominant sugar composition was speculated to be fructose in 'Lvmi-1' fruit while sucrose in 'Yilv' fruit at the early fruit developmental stages. Moreover, the predominant acids in 'Yilv' and 'Lvmi-1' were citric acid followed by quinic acid, malic acid, and oxalic acid. The expression of sugar- and starch-related genes encoding the crucial enzymes suggested different changes in 'Yilv' and 'Lvmi-1'. Notably, a subsequent correlation analysis showed a significant positive correlation between sucrose phosphate synthase (SPS) expression and glucose in 'Yilv', fructokinase (FK) expression, and starch content in 'Lvmi-1', implying their vital roles in sugar and starch accumulation. By contrast, a significant negative correlation between FK expression and fructose in 'Lvmi-1' fruit was observed.
In summary, our results provide supplementary information for the dynamic changes of nutritional compounds and antioxidant capacity during hardy kiwifruit maturity time and give a clue for exploring the mechanism of sugar and starch accumulation in hardy kiwifruit.
中华狝猴桃（）含有多种营养和生物活性化合物，是狝猴桃育种的重要资源。在进行基因改良或栽培优化之前，需要深入了解果实发育和成熟过程中营养成分的组成及积累的动态变化。
在本研究中，对两个中华狝猴桃品种‘伊吕’和‘绿蜜1号’的植物化学分析表明，它们形态各异，‘绿蜜1号’果实直径较大，而垂直果实直径比‘伊吕’小。两个品种的抗氧化能力在成熟过程中均下降，且两者之间无显著差异。此外，尽管葡萄糖在成熟过程中逐渐增加，但推测在果实发育早期，‘绿蜜1号’果实中主要的糖类成分是果糖，而‘伊吕’果实中是蔗糖。而且，‘伊吕’和‘绿蜜1号’中主要的酸是柠檬酸，其次是奎尼酸、苹果酸和草酸。编码关键酶的糖和淀粉相关基因的表达在‘伊吕’和‘绿蜜1号’中呈现不同变化。值得注意的是，随后的相关性分析表明，‘伊吕’中蔗糖磷酸合酶（SPS）表达与葡萄糖之间、‘绿蜜1号’中果糖激酶（FK）表达与淀粉含量之间存在显著正相关，这表明它们在糖和淀粉积累中起重要作用。相比之下，在‘绿蜜1号’果实中观察到FK表达与果糖之间存在显著负相关。
总之，我们的研究结果为中华狝猴桃成熟过程中营养成分和抗氧化能力的动态变化提供了补充信息，并为探索中华狝猴桃糖和淀粉积累机制提供了线索。
