Cloning And Fuctional Analysis Of Seed Rot Resistance Genes In Maize

Maize(Zea mays L.)is one of the most important cereals in the world for its high yield potential and great demand as food,feed and industrial purpose.Maize is suffered in a variety of biotic and abiotic stress during their lifetime,which seriously affects its final yield and quality.As one of the pathogenic fungi,Fusarium verticillioide(F.verticillioide)can be transmitted by seed and cause systemic infection of maize.The mycotoxin produced by F.verticillioides on the kernel has harmful effect on animal and human health.Some significant SNP and QTLs were identified by GW AS and likage anlasis in previous study.On this base,two candidate genes were cloned,whose resistance mechanism were anlazed.Then fuctional markers were developed for resistant molecular breeding.The main results of this study are listed as follows:1)The most significant SNP of GW AS located on the gene GRMZM2G009818,which was a receptor-like kinase as a typical R gene structure.Then transgenetic plants were constructed by RNAi vector.Significant phenotype separations were found in the T2 plants of two To transgenic events.The seeds of positive transgenic T1 plants showed significant higher disease grades than their non-transgenic siblings.Hence,the test demonstrated that GRMZM2G009818 is a key resistance gene to Fusarium seed rot,which was named Seed Rot Resistance gene 1(SRR1).2)qRF1 was mapped to a 1.1 Mb region by NILs.A significant SNP of GWAS was at this region,which located in the gene GRMZM2G008122.Then transgenetic plants were constructed by RNAi vector.The seeds of positive transgenic T2 plants showed significant higher disease grades than WT.Hence,the GRMZM2G008122 were verified as the target gene of qRF1.3)RNA-seq was finished to analyze the molecular function of two candidate genes.The results showed that both of these genes were associated with the upstream of defense response process4)Subcellular localization experiment indicated that SRR1 is distributed on the plant cytomembrane as are most Pattern Recognition Receptors(PRRs).Then the qRT-PCR showed that SRR1 can regulate PTI,ETI and SA signal.5)SRR1 were cloned in 13 resistant and 12 susceptible inbred lines.59 SNP were found in these lines.Of the 59 SNP,18 SNP had significant frequency difference in resistant and susceptible matierals.After LD analysis,7 SNP were developed as candidate functional markers for SRR1.These results deepen understanding of plant disease resistance mechanism,and provide direct theoretical basis for molecular breeding.