Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, National Engineering Research Centre for Organic-based Fertilizers, Jiangsu Collaborative Innovation Centre for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing, China.
Jiangsu Key Laboratory for the Research and Utilization of Plant Resources, Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, Nanjing, China.
Plant Cell Environ. 2021 Oct;44(10):3412-3431. doi: 10.1111/pce.14140. Epub 2021 Jul 14.
Fusarium wilt is one of the major biotic factors limiting cucumber (Cucumis sativus L.) growth and yield. The outcomes of cucumber-Fusarium interactions can be influenced by the form of nitrogen nutrition (nitrate [NO ] or ammonium [NH ]); however, the physiological mechanisms of N-regulated cucumber disease resistance are still largely unclear. Here, we investigated the relationship between nitrogen forms and cucumber resistance to Fusarium infection. Our results showed that on Fusarium infection, NO feeding decreased the levels of the fungal toxin, fusaric acid, leaf membrane oxidative, organelle damage and disease-associated loss in photosynthesis. Metabolomic analysis and gas-exchange measurements linked NO mediated plant defence with enhanced leaf photorespiration rates. Cucumber plants sprayed with the photorespiration inhibitor isoniazid were more susceptible to Fusarium and there was a negative correlation between photorespiration rate and leaf membrane injury. However, there were positive correlations between photorespiration rate, NO assimilation and the tricarboxylic acid (TCA) cycle. This provides a potential electron sink or the peroxisomal H O catalysed by glycolate oxidase. We suggest that the NO nutrition enhanced cucumber resistance against Fusarium infection was associated with photorespiration. Our findings provide a novel insight into a mechanism involving the interaction of photorespiration with nitrogen forms to drive wider defence.
镰刀菌枯萎病是限制黄瓜（Cucumis sativus L.）生长和产量的主要生物因素之一。氮营养形式（硝酸盐[NO]或铵[NH]）会影响黄瓜与镰刀菌的相互作用的结果；然而，氮调控黄瓜抗病性的生理机制在很大程度上仍不清楚。在这里，我们研究了氮形式与黄瓜对镰刀菌感染抗性之间的关系。我们的结果表明，在镰刀菌感染时，施氮会降低真菌毒素镰刀菌酸的水平、叶片膜氧化、细胞器损伤和与光合作用相关的损失。代谢组学分析和气体交换测量将 NO 介导的植物防御与增强的叶片光呼吸速率联系起来。用光呼吸抑制剂异烟肼喷洒的黄瓜植物更容易受到镰刀菌的感染，并且光呼吸速率与叶片膜损伤之间呈负相关。然而，光呼吸速率、NO 同化和三羧酸（TCA）循环之间存在正相关。这为过氧化物酶体 H O 催化的乙醛酸氧化酶提供了潜在的电子汇或。我们认为，NO 营养增强了黄瓜对镰刀菌感染的抗性与光呼吸有关。我们的发现为涉及光呼吸与氮形式相互作用以驱动更广泛防御的机制提供了新的见解。
