Induction of reactive oxygen species and the potential role of NADPH oxidase in hyperhydricity of garlic plantlets in vitro

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• 作者：Jie Tian ; Yaqi Cheng ; Xiangyu Kong ; Min Liu ; Fangling Jiang ; Zhen Wu
• 关键词：Garlic ; Plantlet in vitro ; Reactive oxygen species ; NADPH oxidases ; Cell wall POD ; Apoplast PAO ; Hyperhydricity
• 刊名：Protoplasma
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：254
• 期：1
• 页码：379-388
• 全文大小：
• 刊物类别：Biomedical and Life Sciences
• 刊物主题：Cell Biology; Plant Sciences; Zoology;
• 出版者：Springer Vienna
• ISSN：1615-6102
• 卷排序：254

文摘

Hyperhydricity is a physiological disorder associated with oxidative stress. Reactive oxygen species (ROS) generation in plants is initiated by various enzymatic sources, including plasma membrane-localized nicotinamide adenine dinucleotide phosphate (NADPH) oxidases, cell wall-bound peroxidase (POD), and apoplastic polyamine oxidase (PAO). The origin of the oxidative burst associated with hyperhydricity remains unknown. To investigate the role of NADPH oxidases, POD, and PAO in ROS production and hyperhydricity, exogenous hydrogen peroxide (H₂O₂) and inhibitors of each ROS-producing enzyme were applied to explore the mechanism of oxidative stress induction in garlic plantlets in vitro. A concentration of 1.5 mM H₂O₂ increased endogenous ROS production and hyperhydricity occurrence and enhanced the activities of NADPH oxidases, POD, and PAO. During the entire treatment period, NADPH oxidase activity increased continuously, whereas POD and PAO activities exhibited a transient increase and subsequently declined. Histochemical and cytochemical visualization demonstrated that specific inhibitors of each enzyme effectively suppressed ROS accumulation. Moreover, superoxide anion generation, H₂O₂ content, and hyperhydric shoot frequency in H₂O₂-stressed plantlets decreased significantly. The NADPH oxidase inhibitor was the most effective at suppressing superoxide anion production. The results suggested that NADPH oxidases, POD, and PAO were responsible for endogenous ROS induction. NADPH oxidase activation might play a pivotal role in the oxidative burst in garlic plantlets in vitro during hyperhydricity.