Hydrogen peroxide mediates spermidine-induced autophagy to alleviate salt stress in cucumber

Yuemei Zhang; Yu Wang; Wenxu Wen; Zhengrong Shi; Qinsheng Gu; Golam Jalal Ahammed; Kai Cao; Mohammad Shah Jahan; Sheng Shu; Jian Wang; Jin Sun; Shirong Guo

doi:10.1080/15548627.2020.1847797

Hydrogen peroxide mediates spermidine-induced autophagy to alleviate salt stress in cucumber

Autophagy. 2021 Oct;17(10):2876-2890. doi: 10.1080/15548627.2020.1847797. Epub 2020 Nov 29.

Authors

Yuemei Zhang¹, Yu Wang¹, Wenxu Wen¹, Zhengrong Shi¹, Qinsheng Gu², Golam Jalal Ahammed³, Kai Cao⁴, Mohammad Shah Jahan¹, Sheng Shu^{1

5}, Jian Wang¹, Jin Sun^{1

5}, Shirong Guo^{1

5}

Affiliations

¹ College of Horticulture, Nanjing Agricultural University, Nanjing, China.
² Zhengzhou Fruit Research Institute, Chinese Academy of Agricultural Sciences, Zhengzhou, China.
³ College of Forestry, Henan University of Science and Technology, Luoyang, China.
⁴ The Agriculture Ministry Key Laboratory of Agricultural Engineering in the Middle and Lower Reaches of Yangtze River, Institute of Agricultural Facilities and Equipment, Jiangsu Academy of Agricultural Sciences, Nanjing, China.
⁵ Suqian Academy of Protected Horticulture, Nanjing Agricultural University, Suqian, China.

Abstract

Autophagy, an evolutionally conserved cellular degradation process, plays critical roles in plant development and stress response. Despite the wealth of information on the vital role of autophagy in responses to environmental stresses, little is known about the regulation of autophagy. In this study, we demonstrated that spermidine (Spd), a kind of polyamine, was involved in the regulation of salt tolerance through activating the expression of ATG (autophagy-related) genes and the formation of autophagosomes in cucumber under salt stress. Furthermore, NADPH oxidase-derived apoplastic H₂O₂-mediated Spd-induced salt tolerance and autophagy. Exogenous Spd significantly increased the tolerance to salt stress and inhibited the accumulation and ubiquitination of insoluble proteins. Foliar application of Spd promoted the transcript levels of ATG genes and autophagosomes formation. Besides, Spd induced the expression of RBOH (respiratory burst oxidase homolog), and the accumulation of H₂O₂ both in leaves and roots. However, either pretreatment with dimethylthiourea (DMTU, an H₂O₂ scavenger) or diphenyleneiodonium chloride (DPI, an inhibitor of NADPH oxidase) reduced Spd-induced accumulation of apoplastic H₂O₂. Importantly, Spd-induced salt tolerance and autophagy were compromised when plants were pretreated with DMTU or DPI. Furthermore, the silencing of ATG4 and ATG7 reduced Spd-induced salt tolerance and autophagosomes formation. Taken together, these results revealed that RBOH-dependent H₂O₂ mediated the Spd-induced autophagy and salt tolerance in cucumber.Abbreviations: Asat: light-saturated rate of CO₂ assimilation; ATG: autophagy-related; DCF-DA: 2, 7-dichlorofluorescein diacetate; DMTU: dimethylthiourea; DPI: diphenyleneiodonium chloride; DW: dry weight; EL: electrolyte leakage; FW: fresh weight; Fv/Fm: the maximum quantum yield of photosystem II; GFP: green fluorescent protein; MDC: monodansylcadaverine; PDS: phytoene desaturase; PE: phosphatidylethanolamine; PLD: phospholipase D; RBOH: respiratory burst oxidase homolog; ROS: reactive oxygen species; SDS-PAGE: sodium dodecyl sulfate-polyacrylamide gel electrophoresis; SIN1: salt induced NAC1; Spd: spermidine; TOR: target of rapamycin; VIGS: virus-induced gene silencing.

Keywords: Autophagy; cucumber; hydrogen peroxide; salt stress; spermidine.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Autophagy / genetics
Cucumis sativus* / genetics
Cucumis sativus* / metabolism
Hydrogen Peroxide / pharmacology
Salt Stress
Spermidine / pharmacology

Substances

Hydrogen Peroxide
Spermidine

Grants and funding

This work was supported by the National Key Research and Development Program of China (2018YFD1000800), the National Natural Science Foundation of China (31801902), the China Postdoctoral Science Foundation (2019M661867 and 2019T120433), the Fundamental Research Funds for the Central Universities (KJQN201928) and the China Agriculture Research System (CARS-23-B12).