Arbuscular mycorrhiza induces low oxidative burst in drought-stressed walnut through activating antioxidant defense systems and heat shock transcription factor expression

Wen-Ya Ma; Qiu-Yun Qin; Ying-Ning Zou; Kamil Kuča; Bhoopander Giri; Qiang-Sheng Wu; Abeer Hashem; Al-Bandari Fahad Al-Arjani; Khalid F Almutairi; Elsayed Fathi Abd Allah; Yong-Jie Xu

doi:10.3389/fpls.2022.1089420

Arbuscular mycorrhiza induces low oxidative burst in drought-stressed walnut through activating antioxidant defense systems and heat shock transcription factor expression

Front Plant Sci. 2022 Nov 29:13:1089420. doi: 10.3389/fpls.2022.1089420. eCollection 2022.

Authors

Affiliations

¹ Tibet Plateau Walnut Industry Research Institute/College of Horticulture and Gardening, Yangtze University, Jingzhou, Hubei, China.
² Department of Chemistry, Faculty of Science, University of Hradec Kralove, Hradec Kralove, Czechia.
³ Department of Botany, Swami Shraddhanand College, University of Delhi, New Delhi, India.
⁴ Botany and Microbiology Department, College of Science, King Saud University, Riyadh, Saudi Arabia.
⁵ Plant Production Department, College of Food and Agricultural Sciences, King Saud University, Riyadh, Saudi Arabia.
⁶ Hubei Key Laboratory of Economic Forest Germplasm Improvement and Resources Comprehensive Utilization, Hubei Collaborative Innovation Center for the Characteristic Resources Exploitation of Dabie Mountains, Huanggang Normal University, Huanggang, China.
⁷ Hubei Academy of Forestry, Wuhan, China.

Abstract

Arbuscular mycorrhizal fungi (AMF) have important roles in enhancing drought tolerance of host plants, but it is not clear whether and how AMF increase drought tolerance in walnut (Juglans regia). We hypothesized that AMF could activate antioxidant defense systems and heat shock transcription factors (Hsfs) transcription levels to alleviate oxidative damage caused by drought. The walnut variety 'Liaohe No. 1' was inoculated with Diversispora spurca and exposed to well-watered (WW, 75% of the maximum soil water capacity) and drought stress (DS, 50% of the maximum soil water capacity) for 6 weeks. Plant growth, antioxidant defense systems, and expressions of five JrHsfs in leaves were studied. Such drought treatment inhibited root mycorrhizal colonization, while plant growth performance was still improved by AMF inoculation. Mycorrhizal fungal inoculation triggered the increase in soluble protein, glutathione (GSH), ascorbic acid (ASC), and total ASC contents and ascorbic peroxidase and glutathione reductase activities, along with lower hydrogen peroxide (H₂O₂), superoxide anion radical (O₂ ^•-), and malondialdehyde (MDA) levels, compared with non-inoculation under drought. Mycorrhizal plants also recorded higher peroxidase, catalase, and superoxide dismutase activities than non-mycorrhizal plants under drought. The expression of JrHsf03, JrHsf05, JrHsf20, JrHsf22, and JrHsf24 was up-regulated under WW by AMF, while the expression of JrHsf03, JrHsf22, and JrHsf24 were up-regulated only under drought by AMF. It is concluded that D. spurca induced low oxidative burst in drought-stressed walnut through activating antioxidant defense systems and part Hsfs expressions.

Keywords: arbuscular mycorrhiza; heat shock transcription factor; reactive oxygen species; symbiosis; water stress.