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Many studies have been dedicated to the indispensable roles of jasmonate in plant growth and defence,but the molecular mechanisms preventing the overproduction or accumulation of jasmonate which often has detrimental effect on plant development and physiology are largely unknown.In this study,we found that transcript level of HSB1 gene was greatly down-regulated by MeJA application and the loss-of-function mutants of HSB1 gene accumulated significantly more jasmonate but less ethylene than WT plants.Mutations in HSB1 caused pleiotropic effects on various developmentally regulated processes such as seed weight,root elongation,petal size,flower timing,anthocyanin biosynthesis and leaf senescence.The mutants were more susceptible to pests and pathogens attacks as they displayed enhanced disease symptoms in response to fungal and bacterial pathogens Botrytis cinema and Pseudomonas syringae pv.Tomato DC3000 (Pst DC3000),and the larvae of phytophagous insects Spodoptera exigua increased weight more rapidly when fed on the mutant than on WT plants.However,the mutant plants exhibited enhanced resistance to the root-infecting fungal pathogen Fusarium oxysporum which can produce ethylene itself.In addition,stomata of the mutant plants were greatly compromised in their ability to close in response to either PstDC3000 or PstDC3000 (avrB).Furthermore,mutations in HSB1 gene caused hypersensitivity to high sugar induced anthocynin production and seedling growth arrest.We also provided evidence that HSB1 is not only critical for a tight control of jasmonate production and accumulation but also for the interaction of plant hormones including JA and ET in plant development and stress response.