Rice False Smut Resistant QTL Location Of Rice Material MR183-2

Rice is an important grain crop,and its output affects the food security of the world.Rice false smut is another rice disease with a wide incidence and serious yield after the three diseases of rice,include blast,sheath blight and bacterial blight.It was a secondary disease in past,but it gradually rised to the main disease with the change of global warming and cultivation measures.The most effective method for controlling rice false smut is to select disease resistant varieties.As a result,the study of rice false smut started late,and the germplasm resources of resistance to rice false smut were still less.MR183-2is a high resistant rice material to rice false smut from early germplasm identification.And it is used to create new resistant restorer lines to rice false smut,but the source of its resistance is not yet clear.Furthermore,there are few reports on rice false smut resistance genes at home and abroad.In this experiment,08R2394 and high sense of false smut of rice materials-MR183-2were used to construct recombinant inbred lines,through field resistance identification,gene chip polymorphism detection,single marker analysis,and the resistance QTL of the disease in MR183-2 is located,which laid the foundation for rational utilization of rice resources.The main results are as follows:1.Exploring the genetic model of rice resistance to rice false smut through the positive and negative cross on MR183-2 and 08R2394,F₁ populations were 35.42%and21.43%diseased panicle rate,which susceptible to disease,the average performance is closer to 08R2394.Then F1 further selfing,343 single plants of F₂ were obtained,inside,76 single plants were resistant,and 267 single plants were susceptible.The separation ratio is 1:3.51,which is consistent with the theoretical value by X2 test.In conclusion,the resistance of MR183-2 is recessive,controlled by a pair of genes.2.4 QTLs were located through gene chip analysis and SSR marker combination,two of them were named qFsr2-1,qFsr2-2 on chromosome 2,RM71-HEX and KYgmC02B-TAM were associated marker respectively;one of them named qFsr3-1 on chromosome 3 was associated with marker W068C03C-FAM;one of them was named qFsr8-1 on chromosome 8,the most closely linked with RM5556-FAM marker.Totally,qFsr2-1,qFsr2-2,qFsr3-1 were from MR183-2,except qFsr8-1.3.Because the major quantitative trait Ghd8 which has been reported and cloned is only 0.2Mb apart from SSR marker RM5556-FAM,so Ghd8 is regarded as a candidate gene.And functional verification was performed on chromosome 8 QTL based on Agronomic Traits and sequencing analysis,total grain number,grain density,tiller number statistics,were counted in the most resistant genotype,resistant genotype and the most susceptible genotype,resistant genotype and the most susceptible genotype were different QTL genotypes on chromosome 2 and chromosome 3,the former was the receptor genotype,but the latter was donor genotype,resistance genotype was lower than the most susceptible genotype in the three index,indicating that resistance and yield traits have a certain antagonism.The most resistant and moderate resistant were different genotypes on chromosome 8,the most resistant was the receptor genotype,moderate resistance is the donor genotype.The most resistant was lower than moderate resistant genotype in the three index,indicating that QTL on 8 chromosome is closely related to the yield traits.Moreover,the Ghd8 gene of the parent was amplified and sequenced.On chromosome 8,the receptor genotype 08R2394 was missing a base in 323bp,and the donor genotype MR183-2 was normal.However,the location was in the CBFD NFYB HMF functional domain,and the function change or loss because of the code mutation,indicating that the Ghd8 related function of MR183-2 is normal and regulates the yield traits.It is presumed that QTL located on chromosome 8 is probably Ghd8.