Studies On Genetic Transformation Of Trichome Development-related Gene SmTTG1 In Saussurea Medusa Maxim

Saussurea medusa Maxim,from the family Compositae,is a rare and endangered medicinal plant growing in the Qinghai-Tibet plateau.It is also a typical alpine snowline plant.Thick covering of trichomes is its mainly morphological characteristics,which is an adaptive structure of S.medusa to the extreme environments.It has important theoretical significance for investigating the adaptive mechanisms of alpine plants to the environments through studying the formation and development of trichomes in S.medusa.In this study,the trichome developmentrelated SmTTG1 gene of S.medusa was chosen as experimental subject.The plant expression vector containing SmTTG1 was constructed.The SmTTG1 was transformed into Nicotiana tabacum by Agrobacterium tumefaciens-mediated.The main results were as follows:(1)According to the sequence of SmTTG1 gene of S.Medusa cloned in our laboratory(genbank accession number:KX447632),the upstream and downstream primers were designed on both sides of coding sequence(CDS).The enzyme cutting site Sal I and Bam H I were added to the 5 ’end of the upstream and downstream primers respectively.The CDS sequence of SmTTG1 containing the enzyme cutting sites was cloned.(2)Through enzyme digestion method,the SmTTG1 gene was inserted into multiple clone site in plasmid pRI 101-AN DNA,which constructed the plant expression vector pRI 101-AN-smTTG1.The plasmid containing SmTTG1 was transformed into A.tumefaciens C58C1 by freeze-thawing method.(3)The target gene SmTTG1 was transformed into N.tabacum by A.tumefaciens C58C1 as vector.Eight transgenic tobacco plants were obtained by PCR and RT-PCR analysis.Comparison of the morphology showed that no significant difference was observed between transgenic and non-transgenic plants.This suggested that overexpression of SmTTG1 was not likely to affect the morphology of N.tabacum.