Abstract: In MADS-box family，PAP3 and PPI gene jointly control the growth of petals and stamen. Both of them are class B genes，which in charge of dominating floral organ development. In order to verify PAP3 protein and PPI protein interaction furtherly，yeast two-hybrid system was used in this study，we constructed yeast expression vectors pGBKT7-PPI and pGADT7-PAP3 transformed into corresponding AH109 yeast cells，and made sure that they did not appear the self-activation and toxicity. The yeast zygote diploids（pGBKT7-PPI × pGADT7-PAP3）exhibit on selective agar plates；Meanwhile，we used fusion GST-PAP3 protein and His-PPI protein perform the vitro GST-Pull down technology in this study. The two experimental results showed that specific interactions between PAP3 protein and PPI protein.

Key words: pepper, PAP3, PPI, MADS-box family, Y2H；, GST-Pull down