AUTHOR=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 TITLE=Comparative changes of health-promoting phytochemicals and sugar metabolism of two hardy kiwifruit (Actinidia arguta) cultivars during fruit development and maturity JOURNAL=Frontiers in Plant Science VOLUME=13 YEAR=2022 URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.1087452 DOI=10.3389/fpls.2022.1087452 ISSN=1664-462X ABSTRACT=Introduction

Hardy kiwifruit (Actinidia arguta) 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.

Methods

In the present study, the phytochemical analysis of two A. arguta 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.

Results and Discussion

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.