Gene Silence And Function Analysis Of Potato (Solanum Tuberosum L) Brassinosteroids Receptor Stbri1

Brassinosteroids(BRs)play an important role in plant growth and development.The BRs' receptor(BRI1)is a key component of BR signaling pathway.Potato is a very important crop.The function research of BRs receptor gene may help to improve the understanding of the regulation of BRs on potato growth and development,more importantly,the tuber growth and development.Also,this research may be greatly meaningful in genetic improvement of crops similar to potato whose tubers are the main products.In this research,we explored the function characteristics of StBRI1 in vitro,confirmed the biological function of StBRI1 in an Arabidopsis BRI1 weak mutant bri1-5.We also generated whole-plant and tuber-specific StBRI1 RNAi lines using CaMV 35 S and B33 promoter respectively.Through measurement of parameters of plant growth and development and tuber yield and quality,we identified function characteristics of StBRI1 and the receptor's effects on growth and development of potato plant and tubers.The results are as follows:1.StBRI1 has the activity of autophosphorylation and transphosphorylation and locates oncytomembrane.2.The expression level of StBRI1 is higher in active and young parts of potato plants(root,stolon,young leaves),but lower in stem and old leaves.In tubers,the expression level becomes higher along with tubers' growth and development.3.Overexpression of StBRI1 can partly rescue the phenotype of Arabidopsis BRI1 weak mutant bri1-5,which indicates it's function homology with AtBRI1.4.RNAi vectorspART27-35S-StBRI1 RNAi and pBI121-B33-StBRI1 RNAi are constructed successfully and transformed into potato(Solanum tuberosum L.cv.Désirée).Whole-plant and tuber-specific StBRI1 RNAi lines are obtained and confirmed.5.Whole-plant StBRI1 RNAi lines show the phenotype of compact status,lower plant height,shorter internode,slender stem and potiole,dark green and small leaves.But there is no significant difference in node number between RNAi lines and wildtype plants.Shorter stem cell can be observed by microscope.6.Tuber yield of both whole-plant and tuber-specific StBRI1 RNAi lines decreases.Besides,in tuber-specific StBRI1 RNAi lines,decrease of tuber number per plant is mainly responsible for the yield fail.7.In the tubers of whole-plant StBRI1 RNAi lines,starch content decrease but soluble sugar content increase.In the tubers of whole-plant StBRI1 RNAi lines,starch content increase but there is no significant change in soluble sugar content.