Functional Studies On Rice OsSGL And Its Homologous Gene AtSGL In Regulating Plant Growth,Development And Stress Tolerance

OsSGL(Stress tolerance and Grain Length)has been reported as a gene whose expression is induced by various stresses.The protein encoded by this gene contains a conserved domain of DUF1645,and its overexpression in 9311 resulted in increased grain length while overexpression of OsSGL in Arabidopsis resulted in enhanced drought tolerance.However,the role of this gene in regulating growth and grain shape in japonica cultivars is unknown.In order to study the function of OsSGL in conventional japonica rice varieties that need to improve grain shape and grain weight,this project studies how OsSGL and its homologous gene AtSGL regulate plant growth and development,and observe and analyze agronomic traits and stress tolerance.The main results are the following:1、Most of the important economic crops,such as rape,soybean,peanut,cucumber,etc.are dicotyledonous plants.2、In order to evaluate the value of the heterologous expression of OsSGL gene in dicotyledonous plants to improve yield,this project took Arabidopsis thaliana as the research object and constructed OsSGL heterologous overexpression lines.However,phenotypic analysis demonstrated that heterologous expression of OsSGL in Arabidopsis inhibited plant height,seed length,width and seed size,and reduced rosette leaves,shortened rosette petioles,and inhibited rosette leaf extension.It is suggested that heterologous expression of a monocotyledonous gene in a dicotyledonous plant may not necessarily effectively utilize this excellent gene due to distincted functions in two systems.3、In view of the different functions of OsSGL gene in rice and Arabidopsis by heterologous expression,this study cloned the orotholog of OsSGL in Arabidopsis thaliana termed as AtSGL.Although there was no significant difference in plant height between the AtSGL gain-of-function weak mutant and the wild type,the rosette leaves were significantly reduced,the petioles were significantly shortened,and the leaves were reduced,indicating that AtSGL played an important negative regulatory role in the development of Arabidopsis rosette leaves.The function of AtSGL in regulating the growth and development of Arabidopsis may be opposite to that of OsSGL in rice.4、In order to explore the molecular regulation mechanism related to AtSGL,AtSGL protein was fused and expressed with a fluorescent tag protein,and AtSGL was detected to be localized in cell membrane,cytoplasm and nucleus.The interaction between AtSIP1(AtSGL Interacting Protein 1)protein and AtSGL was further screened by yeast two-hybrid screening library.AtSIP2 and AtSIP3,which belong to the same family as AtSIP1,may also interact with AtSGL.The deficiency of AtSIP1,AtSIP2 and AtSIP3 inhibited the plant height,rosette leaf number,petiole elongation and leaf expansion in Arabidopsis,indicating that AtSIPs positively regulates the growth and development.Real-time quantitative PCR analysis showed that the expression of AtSGL and AtSIPs was responsive to drought,salt,high temperature,low temperature and ABA.Drought and salt stress treatments were performed on AtSGL and AtSIPs mutants,and it was found that AtSGL inhibited salt tolerance and drought tolerance,while AtSIPs enhanced the salt tolerance and drought tolerance.It was suggested that AtSGL interacts with AtSIPs and antagonically regulates plant growth,development and stress tolerance.This study found that the homologous genes OsSGL and AtSGL have different regulatory effects on plant growth,development and stress tolerance,and identified AtSIPs family proteins as AtSGL interacting proteins,which play an important role in the regulation of development and stress tolerance.The research results will promote the understanding of the functional differences of homologous genes in dicotyledonous and monocotyledonous plants,and provide important genetic resources for plant stress tolerance and plant morphology improvement.