title: Induction of systemic stress tolerance by brassinosteroid in Cucumis sativus.
abstract: • Brassinosteroids (BRs) are a new class of plant hormones that are essential for plant growth and development. Here, the involvement of BRs in plant systemic tolerance to biotic and abiotic stresses was studied. • The effects of 24-epibrassinolide (EBR) on plant stress tolerance were studied through the assessment of symptoms of photooxidative stress by chlorophyll fluorescence imaging pulse amplitude modulation, the analysis of gene expression using quantitative real-time PCR and the measurement of hydrogen peroxide (H₂O₂) production using a spectrophotometric assay or confocal laser scanning microscopy. • Treatment of primary leaves with EBR induced systemic tolerance to photooxidative stress in untreated upper and lower leaves. This was accompanied by the systemic accumulation of H₂O₂ and the systemic induction of genes associated with stress responses. Foliar treatment of EBR also enhanced root resistance to Fusarium wilt pathogen. Pharmacological study showed that EBR-induced systemic tolerance was dependent on local and systemic H₂O₂ accumulation. The expression of BR biosynthetic genes was repressed in EBR-treated leaves, but elevated significantly in untreated systemic leaves. Further analysis indicated that EBR-induced systemic induction of BR biosynthetic genes was mediated by systemically elevated H₂O₂. • These results strongly argue that local EBR treatment can activate the continuous production of H₂O₂, and the autopropagative nature of the reactive oxygen species signal, in turn, mediates EBR-induced systemic tolerance.
authors.affiliation: Department of Horticulture, Huajiachi Campus, Zhejiang University, Kaixuan Road 268, Hangzhou 310029, China.
authors.forename: Xiao-Jian
authors.initials: XJ
authors.lastname: Xia
authors.affiliation: Department of Horticulture, Huajiachi Campus, Zhejiang University, Kaixuan Road 268, Hangzhou 310029, China.
authors.forename: Yan-Hong
authors.initials: YH
authors.lastname: Zhou
authors.affiliation: Department of Horticulture, Huajiachi Campus, Zhejiang University, Kaixuan Road 268, Hangzhou 310029, China.
authors.forename: Ju
authors.initials: J
authors.lastname: Ding
authors.affiliation: Department of Horticulture, Huajiachi Campus, Zhejiang University, Kaixuan Road 268, Hangzhou 310029, China.
authors.forename: Kai
authors.initials: K
authors.lastname: Shi
authors.affiliation: Department of Applied Biological Chemistry, University of Tokyo, Bunkyo Ku, Tokyo 1138657, Japan.
authors.forename: Tadao
authors.initials: T
authors.lastname: Asami
authors.affiliation: Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907-2054, USA.
authors.forename: Zhixiang
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Department of Horticulture, Huajiachi Campus, Zhejiang University, Kaixuan Road 268, Hangzhou 310029, China.|Key Laboratory of Horticultural Plants Growth, Development and Biotechnology, Agricultural Ministry of China, Kaixuan Road 268, Hangzhou 310029, China.
authors.forename: Jing-Quan
authors.initials: JQ
authors.lastname: Yu
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects*; D060406:Brassinosteroids / Q000494:pharmacology*; D002734:Chlorophyll / Q000378:metabolism; D018553:Cucumis sativus / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D005670:Fusarium / Q000502:physiology; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant / Q000235:genetics; D006861:Hydrogen Peroxide / Q000378:metabolism*; D010935:Plant Diseases / Q000276:immunology / Q000382:microbiology; D010937:Plant Growth Regulators / Q000494:pharmacology*; D057865:Plant Immunity / Q000187:drug effects*; D018515:Plant Leaves / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction; D013260:Steroids, Heterocyclic / Q000494:pharmacology*
chemical_list: D060406:Brassinosteroids; D010937:Plant Growth Regulators; D017382:Reactive Oxygen Species; D013260:Steroids, Heterocyclic; D002734:Chlorophyll; D006861:Hydrogen Peroxide; C023623:brassinolide