Hydrogen peroxide mediates abscisic acid‐induced HSP70 accumulation and heat tolerance in grafted cucumber plants

• Published in: Plant, cell and environment Vol. 37; no. 12; pp. 2768 - 2780
• Main Authors: LI, HAO, LIU, SHAN‐SHAN, YI, CHANG‐YU, WANG, FENG, ZHOU, JIE, XIA, XIAO‐JIAN, SHI, KAI, ZHOU, YAN‐HONG, YU, JING‐QUAN
• Format: Journal Article
• Language: English
• Published: Oxford Blackwell Scientific Publications 01.12.2014; Blackwell; Wiley Subscription Services, Inc
• Subjects: abscisic acid; Abscisic Acid - biosynthesis; Abscisic Acid - pharmacology; Adaptation, Physiological - drug effects; Adaptation, Physiological - genetics; Biological and medical sciences; biosynthesis; chlorophyll; cucumbers; Cucumis sativus; Cucumis sativus - drug effects; Cucumis sativus - genetics; Cucumis sativus - physiology; fluorescence; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Plant - drug effects; grafting; heat; heat shock proteins; heat stress; heat tolerance; Heat-Shock Response - drug effects; Heat-Shock Response - genetics; HSP70 Heat-Shock Proteins - genetics; HSP70 Heat-Shock Proteins - metabolism; hydrogen peroxide; Hydrogen Peroxide - pharmacology; immunoassays; Luffa cylindrica; Models, Biological; oxidative stress; photoinhibition; photosystem II; Plant Leaves - drug effects; Plant Leaves - metabolism; Plant Roots - drug effects; Plant Roots - physiology; Plant Shoots - drug effects; Plant Shoots - physiology; plant stress; Respiratory burst oxidase homolog; RNA, Messenger - genetics; RNA, Messenger - metabolism; roots; rootstocks; root–shoot communication; shoots; stress response; Time Factors; Up-Regulation - drug effects; Up-Regulation - genetics; Western blotting; Heat resistance; Oxidative stress; Hydrogen peroxide; Cucumis salivus; Oxidase; Grafting; Accumulation; Dicotyledones; Sesquiterpenes; Angiospermae; Abscisic acid; Plant growth substance; Luffa cylindrica; Root; Enzyme; Cucurbitaceae; Plant ecology; Cucumis sativus; Respiratory burst oxidase homolog; Vegetable crop; Spermatophyta; Oxidoreductases; Thermotolerance; Respiration; root-shoot communication; oxidative stress; grafting
• ISSN: 0140-7791; 1365-3040
• DOI: 10.1111/pce.12360

Root–shoot communications play important roles in plant stress responses. Here, we examined the roles of root‐sourced signals in the shoot response to heat in cucumber plants. Cucumber plants grafted onto their own roots and luffa roots were exposed to aerial and root‐zone heat to examine their tolerance by assessing the levels of oxidative stress, PSII photoinhibition, accumulation of abscisic acid (ABA), H₂O₂and heat shock protein (HSP) 70 using immunoblotting, chlorophyll fluorescence, immunoassay, CeCl₃staining and Western blotting, respectively. Grafting onto the luffa rootstock enhanced the shoot tolerance to the heat. This enhanced tolerance was associated with increased accumulation of ABA and apoplastic H₂O₂, RBOH transcripts and HSP70 expression and a decrease in oxidative stress in the shoots. The increases in the ABA and H₂O₂concentrations in the shoots were attributed to an increase in ABA transport from roots and an increase in ABA biosynthesis in the shoots when the root‐zone and shoots were heat stressed, respectively. Inhibition of H₂O₂accumulation compromised luffa rootstock‐induced HSP70 expression and heat tolerance. These results suggest that, under heat stress, ABA triggers the expression of HSP70 in an apoplastic H₂O₂‐dependent manner, implicating the role of an ABA‐dependent H₂O₂‐driven mechanism in a systemic response involving root–shoot communication.