Exogenous niacin treatment increases NADPH oxidase in kiwifruit

Abstract Kiwifruit are a popular fruit worldwide; however, plant growth is threatened by abiotic stresses such as drought and high temperatures. Niacin treatment in plants has been shown to increase NADPH levels, thus enhancing abiotic stresses tolerance. Here, we evaluate the effect of niacin solution spray treatment on NADPH levels in the kiwifruit cultivars Hayward and Xuxiang. We found that spray treatment with niacin solution promoted NADPH and NADP+ levels and decreased both O2·- production and H2O2 contents in leaves during a short period. In fruit, NADPH contents increased during early development, but decreased later. However, no effect on NADP+ levels has been observed throughout fruit development. In summary, this report suggests that niacin may be used to increase NADPH oxidases, thus increasing stress-tolerance in kiwifruit during encounter of short-term stressful conditions.

摘要 猕猴桃是全球广受欢迎的果品，但其植株生长常受到干旱、高温等非生物胁迫的威胁。已有研究证实，对植物施加烟酸处理可提升烟酰胺腺嘌呤二核苷酸磷酸（NADPH）水平，进而增强植株对非生物胁迫的耐受性。本研究以‘海沃德（Hayward）’与‘徐香（Xuxiang）’两个猕猴桃品种为试材，评估了烟酸溶液喷雾处理对其叶片NADPH水平的影响。结果显示，短期喷施烟酸溶液可提升叶片内NADPH与烟酰胺腺嘌呤二核苷酸磷酸（NADP+）水平，同时降低叶片中超氧阴离子（O₂·⁻）的生成量与过氧化氢（H₂O₂）的含量。在果实发育阶段，NADPH水平在发育早期呈上升趋势，后期则有所下降；但在整个果实发育期内，未观察到烟酸处理对NADP+水平产生显著影响。综上，本研究提示烟酸可通过提升NADPH氧化酶（NADPH oxidases）活性，增强猕猴桃在遭遇短期逆境胁迫时的抗逆能力。