title: The ABI2-dependent abscisic acid signalling controls HrpN-induced drought tolerance in Arabidopsis.
abstract: HrpN, a protein produced by the plant pathogenic bacterium Erwinia amylovora, has been shown to stimulate plant growth and resistance to pathogens and insects. Here we report that HrpN activates abscisic acid (ABA) signalling to induce drought tolerance (DT) in Arabidopsis thaliana L. plants grown with water stress. Spraying wild-type plants with HrpN-promoted stomatal closure decreased leaf transpiration rate, increased moisture and proline levels in leaves, and alleviated extents of damage to cell membranes and plant drought symptoms caused by water deficiency. In plants treated with HrpN, ABA levels increased; expression of several ABA-signalling regulatory genes and the important effector gene rd29B was induced or enhanced. Induced expression of rd29B, promotion of stomatal closure, and reduction in drought severity were observed in the abi1-1 mutant, which has a defect in the phosphatase ABI1, after HrpN was applied. In contrast, HrpN failed to induce these responses in the abi2-1 mutant, which is impaired in the phosphatase ABI2. Inhibiting wild-type plants to synthesize ABA eliminated the role of HrpN in promoting stomatal closure and reducing drought severity. Moreover, resistance to Pseudomonas syringae developed in abi2-1 as in wild-type plants following treatment with HrpN. Thus, an ABI2-dependent ABA signalling pathway is responsible for the induction of DT but does not affect pathogen defence under the circumstances of this study.
authors.affiliation: Department of Plant Pathology, Nanjing Agricultural University, 1 Weigang, Nanjing, 210095, China.
authors.forename: Hong-Ping
authors.initials: HP
authors.lastname: Dong
authors.forename: Haiqin
authors.initials: H
authors.lastname: Yu
authors.forename: Zhilong
authors.initials: Z
authors.lastname: Bao
authors.forename: Xiaojing
authors.initials: X
authors.lastname: Guo
authors.forename: Jianling
authors.initials: J
authors.lastname: Peng
authors.forename: Zhen
authors.initials: Z
authors.lastname: Yao
authors.forename: Guangyong
authors.initials: G
authors.lastname: Chen
authors.forename: Shuping
authors.initials: S
authors.lastname: Qu
authors.forename: Hansong
authors.initials: H
authors.lastname: Dong
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D000220:Adaptation, Biological / Q000187:drug effects; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D001425:Bacterial Outer Membrane Proteins / Q000494:pharmacology*; D003681:Dehydration; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D009154:Mutation; D010641:Phenotype; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects*
chemical_list: D001425:Bacterial Outer Membrane Proteins; C075462:harpin protein, Erwinia amylovora; D000040:Abscisic Acid; C106443:ABI2 protein, Arabidopsis; D010749:Phosphoprotein Phosphatases