Breeding New Rice Lines With Blast Resistance By Molecular Marker-assisted Selection Of The Pigm Gene

Rice?Oryza sativa L.?is one of the most important food crops in the world.Rice production and quality are closely related to people's livelihood.Rice blast disease is an important disease of rice in the world.At least 80 countries?regions?have reported the occurrence of the disease,and it is very important to study rice blast control.It is the most economical,environmentally friendly and effective measures to reduce the damage of rice blast to rice production by cultivating and promoting the new varieties of disease resistance by excavating and using broad spectrum resistant genes.However,rice blast resistance is a typical quality-quantitative traits,susceptible to a variety of environmental factors,so the conventional rice blast resistance breeding in the phenotypic selection are not allowed,low efficiency.Molecular Marker-assisted Selection?MAS?,which is used to identify and select the marker genotype by molecular markers closely linked to the target gene?or within the gene?.The results are not affected by the environment and the efficiency of breeding Greatly improve.MAS technology is usually an important method of molecular breeding,which is combined with traditional continuous backcross breeding and directional or improved target traits.The Pigm gene,which is used in this study,is a broad spectrum of persistent rice blast genes and has been pinpointed at the Pi2/9 locus of rice chromosome 6.In this study,Gu Mei 4 was used as the donor of Pigm gene.Through the screening and utilization of polymorphic high molecular markers,the resistance of rice blast was improved by molecular marker-assisted selection of backcross breeding.The paper selects 9 key analyzes of high-generation materials.Through the continuous backcrossing,selection and selfing to obtain high-generation disease-resistant materials,and on this basis for high-generation group of genetic and phenotypic analysis of high resistance to rice blast homozygous lines,and through the field of major agronomic And the yield traits were analyzed,and the new resistant lines with different genetic background and recipient parents were obtained.The specific results are as follows:1.The cultivation,subculture and purification of the 28 species of Magnaporthe grisea from different countries or regions kept in the laboratory.A total of 24 rice receptor materials,GuMei 4?Pigm gene donor?,negative control CO39 and positive control 75-1-127?including broad spectrum resistant plague gene Pi9?were analyzed by inoculation of Magnaporthe grisea in vivo.)On the antimicrobial spectrum of 28 strains of Magnaporthe grisea.The results showed that the resistance of Pigm gene donor GuMei 4 to 27 strains showed only resistance to strain E2007046A2 from Hubei,and the resistance frequency was96.4%,which proved that Pigm was indeed a broad spectrum resistance Gene;24 rice receptor material resistance frequency between 25.9%⁵7.1%,indicating that the recipient parent material resistance is poor,narrow spectrum,the need for resistance improvement.2.Genomic analysis of the three co-dominant polymorphic In Dels molecules were screened by genotyping the donor relatives GuMei 4 and 24 recipient parents,respectively:T9E4,S29742,DG-2.Through the screening of high-performance molecular markers,it is convenient to further efficiently screen out the populations containing Pigm gene.3.In this experiment,nine BC₅F₃ disease-resistant lines with Pigm gene?locus?were obtained by continuous backcrossing and self-crossing in Changsha and Sanya through breeding from 2010 to 2016.At the same time,nine pigeons containing Pigm?Site?of the BC₅F₂ population;and access to 16 different generations of Pigm gene?Site?of the backcross population.Through years of experiment,the construction of molecular marker assisted selection breeding group has been basically completed,which lays the foundation for further cultivating new rice variety?combination?with broad spectrum and high resistance to rice blast.4.The rice blast resistance of early indica rice 1701 was improved by molecular marker assisted selection and continuous backcross breeding using the closely linked marker S29742,a broad-spectrum,persistent resistance gene.The resistance and antimicrobial spectrum of Pigm gene donor parent GuMei 4 and recipient parents 1701 were 23.7%and 39.1%respectively for 23 strains of Magnaporthe grisea.S29742 is a PCR-based co-dominant DNA marker,and the polymorphism is evident and stable between GuMei 4 and 1701.A band of about 550 bp and about 900 bp is amplified in the two parents;S29742 The selectivity of the marker genotype to rice blast resistance phenotype was 100%.The BC₅F₂ population with Pigm gene was obtained by continuous backcrossing,selection and selfing,and three BC₅F₃lines with high blast resistance were identified by genotype and phenotypic analysis.The main agronomic and yield traits Analysis,to develop a genetic background and recipient relatives similar to the new strain of rice blast"1701-Pigm".