1 College of Forestry, Henan University of Science and Technology, Luoyang 471023, People's Republic of China.
2 Department of Plant Science, Agricultural and Animal Husbandry College, Tibet University, Linzhi 860000, People's Republic of China.
Phytopathology. 2019 Jun;109(6):972-982. doi: 10.1094/PHYTO-09-18-0342-R. Epub 2019 May 6.
Plant survival in the terrestrial ecosystem is influenced by both beneficial and harmful microbes. spp. are a group of filamentous fungi that promote plant growth and resistance to harmful microbes. Previously, we showed that the genus could effectively suppress Fusarium wilt in cucumber. However, the mechanisms that underlie the effects of the genus on plant defense have not been fully substantiated. Two essential metabolic pathways, such as the ascorbate (AsA)-glutathione (GSH) cycle and the oxidative pentose phosphate pathway (OPPP), have been shown to participate in plant tolerance to biotic stressors; nevertheless, the involvement of these pathways in -induced enhanced defense remains elusive. Here, we show that could alleviate oxidative and nitrostative stress by minimizing reactive oxygen species (ROS; hydrogen peroxide and superoxide) and reactive nitrogen species (nitric oxide [NO]) accumulation, respectively, under infection in cucumber roots. The genus enhanced antioxidant potential to counterbalance the overproduced ROS and attenuated the transcript and activity of NO synthase and nitrate reductase. The genus also stimulated -nitrosylated glutathione reductase activity and reduced -nitrosothiol and -nitrosylated glutathione content. Furthermore, the genus enhanced AsA and GSH concentrations and activated their biosynthetic enzymes, γ-GCS and l-galactono-1,4-lactone dehydrogenase. Interestingly, the genus alleviated -inhibited activity of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase, enzymes involved in the OPPP. Such positive regulation of the key enzymes indicates the adequate maintenance of the AsA-GSH pathway and the OPPP, which potentially contributed to improve redox balance, energy flow, and defense response. Our study advances the current knowledge of -induced enhanced defense against in cucumber.
植物在陆地生态系统中的生存受到有益和有害微生物的影响。 属是一类促进植物生长和抵抗有害微生物的丝状真菌。以前，我们表明 属可以有效地抑制黄瓜枯萎病。然而， 属对植物防御的影响机制尚未得到充分证实。两个重要的代谢途径，如抗坏血酸（AsA）-谷胱甘肽（GSH）循环和氧化戊糖磷酸途径（OPPP），已被证明参与植物对生物胁迫的耐受；然而，这些途径在 属诱导的增强防御中的参与仍不清楚。在这里，我们表明，在黄瓜根系感染 属时， 属可以通过减少活性氧（ROS；过氧化氢和超氧化物）和活性氮（一氧化氮[NO]）的积累来缓解氧化和硝化应激。该属增强了抗氧化能力，以平衡过量产生的 ROS，并减弱了 NO 合酶和硝酸还原酶的转录和活性。该属还刺激了 -亚硝化谷胱甘肽还原酶的活性，降低了 -亚硝酰化谷胱甘肽和 -亚硝酰化谷胱甘肽的含量。此外，该属增加了 AsA 和 GSH 的浓度，并激活了它们的生物合成酶 γ-GCS 和 l-半乳糖酸-1,4-内酯脱氢酶。有趣的是，该属缓解了 属抑制的葡萄糖-6-磷酸脱氢酶和 6-磷酸葡萄糖酸脱氢酶的活性，这些酶参与 OPPP。这些关键酶的正向调节表明 AsA-GSH 途径和 OPPP 的充分维持，这可能有助于改善氧化还原平衡、能量流和防御反应。我们的研究推进了对黄瓜中 属诱导增强防御的认识。
