Cysteine proteases play important roles in intracellular protein degradation,programmed cell death and in responding to environmental stimuli.In this study,we identified a new cysteine protease CP51 from Brassica napus and Arabidopsis thaliana participates in exine formation and anther development.The gene encodes a papain-like subfamily (C1A) cysteine proteinase and is specifically expressed in anthers at stages 9-12 of A.thaliana,which was assessed by qRT-PCR and promoter-GUS fusion detection.