Hydrogen peroxide mediates abscisic acid-induced HSP70 accumulation and heat tolerance in grafted cucumber plants.
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), H2 O2 and heat shock protein (HSP) 70 using immunoblotting, chlorophyll fluorescence, immunoassay, CeCl3 staining 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 H2 O2 , RBOH transcripts and HSP70 expression and a decrease in oxidative stress in the shoots. The increases in the ABA and H2 O2 concentrations 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 H2 O2 accumulation 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 H2 O2 -dependent manner, implicating the role of an ABA-dependent H2 O2 -driven mechanism in a systemic response involving root-shoot communication.
Department of Horticulture, Zijinggang Campus, Zhejiang University, Yuhangtang Road 866, Hangzhou, 310058, China.
Hao
H
Li
Shan-Shan
SS
Liu
Chang-Yu
CY
Yi
Feng
F
Wang
Jie
J
Zhou
Xiao-Jian
XJ
Xia
Kai
K
Shi
Yan-Hong
YH
Zhou
Jing-Quan
JQ
Yu
D000040:Abscisic Acid / Q000096:biosynthesis / Q000494:pharmacology*; D000222:Adaptation, Physiological / Q000187:drug effects* / Q000235:genetics; D018553:Cucumis sativus / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D018869:Heat-Shock Response / Q000187:drug effects* / Q000235:genetics; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D008954:Models, Biological; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000502:physiology; D018520:Plant Shoots / Q000187:drug effects / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013997:Time Factors; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics
D018840:HSP70 Heat-Shock Proteins; D012333:RNA, Messenger; D000040:Abscisic Acid; D006861:Hydrogen Peroxide
Cucumis sativus; Luffa cylindrica; Respiratory burst oxidase homolog; grafting; oxidative stress; root-shoot communication