Abstract: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.