Abstract: In order to reveal the role of WRKY40 gene in response to diseases and environmental stresses，Malus hupehensis（Pamp）Rehd. was used for gene cloning by reverse transcription PCR amplification by using specific primers. Quantitative real-time PCR was used in analyzing gene expression in tissues and in response to stresses，including cold，high salinity，drought，PEG6000 and treatments of exogenous ABA（abscisic acid）and IAA（indole-3-acetic acid）. A 1 240 bp fragment Arabidopsis AtWRKY40，and it is named as MhWRKY40b. Its GenBank accession is JX112913. Gene expression indicated that MhWRKY40b expressed in root，stem，leaf and other tissues，especially high in calyx，petal and fruit. It was clearly induced by cold，high salinity，and drought with more than 20 folds increased expression at the highest level，and slightly induced by PEG osmotic stress，Podosphaera leucotricha，exogenous ABA，and IAA，with less than 10 folds increase at the highest level. MhWRKY40b may have similar function to AtWRKY40 in powdery mildew resistance，it may also have a role in cold，salinity and drought tolerance.

Key words: Malus hupehensis（Pamp）Rehd, WRKY transcription factor, stress tolerance, diseasy resistance, ABA（abscisic acid）