Saussurea involucrata plasma membrane aquaporin protein gene sikPIP₃ was cloned from S.involucrata DNA library which was prepared in laboratory by PCR technique.Then a plant expression vector pBI121-sikPIP₃ was constructed using sikPIP₃ gene.The transgenic tobacco was further obtained through Agrobacterium tumefaciens transformation of tobacco NC89.PCR and RT-PCR analysis indicated that the plasma membrane aquaporin protein gene sikPIP₃ had been integrated into the genome.Water stress method was introduced to analyze drought resistance and freezing stress method was used to analyze cold resistance.The results showed that:(1)Plasma membrane aquaporin protein gene sikPIP₃ was cloned;(2)Growth phenotype of transgenic tobacco is better than that of wild-type after drought treatment,especially under the circumstances without water for 9 days.The wild-type tobacco is wilting completely,and transgenic ones presented mild wilting symptoms;Physiological index analysis results showed that relative conductivity and MDA content of transgenic tobacco is lower than that of wild-type,but relative water content is higher.The drought resistance of sikPIP₃ transgenic tobacco is better than that of wild-type.(3)Growth phenotype of transgenic tobacco is better than that of wild-type after stress treatment with different temperatures,specially under the condition of -4℃ cold treatment for 6 h.The wild-type was wilting completely,however the transgenic-type only emerged little injure spot.Physiological index analysis results showed that relative conductivity and MDA content of genetic tobacco is lower than that of wild-type.The cold resistance of sikPIP₃ transgenic tobacco is better than that of wild-type.Comprehensive results indicated that sikPIP₃ gene has nice applications in resistance genetic engineering.