The Regulation Of Pollen Tube Growth By Xyloglucan Galactosyltransferase PXT And Genetic Screening Of FER Suppressors

Plant cell wall plays an important role in maintaining the shape of plant cells,supplying the normal life activities of the cells and responding to the changes of the external environment.During the polar growth of pollen tube,new cell wall components are deposited in the tip region of pollen tube to maintain cell growth,so the normal synthesis of cell wall components is very important.The primary cell wall of plants is a complex network structure mainly formed by polysaccharides such as cellulose,hemicellulose and pectin.Xyloglucan(XyG)is the most important hemicellulose polysaccharide,which is synthesized by a series of different XyG glycosyltransferases.So far,there are a few studies on XyG galactosyltransferases in pollen tube cell wall.We found pollan expressed XyG galactosyltransferase(PXT)which encode a XyG galactosyltransferase.The phenotypic analysis of pxt mutant showed obvious defective growth of pollen tubes.The in vitro grown pollen tubes were short and swelled in the tip.Further studies on PXT function showed that the mutation of PXT led to the accumulation of XyG that was not galactosylated in the pollen tube cell wall,and the cell wall components such as pectin,callose and cellulose also changed significantly.On the other hand,application of Calcoflour White and Congo Red to the in vitro grown pollen tubes showed that the pxt mutant pollen tubes were more sensitive to exogenous stress,which suggested that the stability of the cell wall was defective.The study shed light to the function of glycosyltransferases in XyG synthesis of pollen tube.Receptor-Like Kinases(RLKs)play an important role in the process of plant growth and development by sensing and transmitting received signals.We have been focused on the functional study of FERONIA(FER)of Catharanthus roseus RLK1-like(Cr RLK1L)family.A variety of phenotypic defects were found in the fer-4mutant and we focused on the obvious inhibition of the growth of root hairs of plants.EMS(Ethyl Methylsulphonate)mutagenesis is a common genetic mutagenesis methods.By EMS mutagenesis of fer-4 mutants,the downstream suppressors of FER signaling pathway will be found,which is conducive to further revealing the important function of FER in the growth and development of Arabidopsis thaliana.Through EMS mutagenesis of fer-4 mutant,one root hair recovery mutant was screened.The genotype of the root hair recovery mutant was identified and it was determined to be homozygous fer-4.Next,we will carry out several rounds of backcrosses and self-crosses between the suppressor line and the fer-4,aiming to check whether it is dominant or recessive and its gene location,find the mutated target gene,and conduct further studies on it.This work provide valuble material for the functional study of FER in plant growth and development.