Screening Of Germplasm Resources For Resistance To Rice Blast And False Smut And Identification Of Blast Resistance Gene And Genetic Improvement Of Yahui 2115

Rice blast and rice false smut are main diseases that affect high yield,stable yieldand food safety of rice.The practice has showed that breeding and planting resistant varieties is the most economical,environmentally friendly and effective measure to control diseases.Screening of disease resistant germplasm resources and discovery of disease resistance genes are the basis for disease resistance breeding.Therefore,This study combined with indoor resistance spectrum analysis and resistance identification in field disease nursery,the resistance of 29 blast-resistant monogenic lines and 223 germplasm resources to blast and false smut of rice were systematically identified and evaluated.Using disease resistance gene expression analysis,transgenic validation and other technical means to discovery the rice blast resistance gene and genetic improvement of the restorer line Yahui2115 which high resistance to rice blast.The main findings are as follows:(1)Screening of Effective Blast Resistance Genes in RiceThe indoor resistance spectrum test and field disease resistance identification results of 2013-2017 years showed that,there were significant differences in blast resistance between 29 monogenic lines,the resistance frequency was 0.24%~94.39%,the leaf blast disease index was 0.15~94.22,the percentage of diseased panicles for neck blast was1.32%~100.00%.The single gene lines which containing Pik~h,Pik~m,Pi9 and Pi2 showed better resistance to blast,among them,the resistance frequency of single gene lines which carrying Pi2 and Pi9 were respectively achieved 94.39%and 90.38%,the percentage of diseased panicles for neck blast only 1.32%and 1.82%,showed highly frequency of resistance to rice blast fungus in Sichuan,stability expressed resistant to neck blast in field disease nursery.Thus it can be seen,the blast resistance genes Pi2 and Pi9 have high utilization value in rice breeding for blast resistance in Sichuan.(2)Screening of germplasm resources for resistance to rice blast and false smutThe results of resistance identification in 2013-2017 years showed that,among 223germplasm resources,have 34 like Yahui 2115,Yahui 2918 and Chenghui 727 which showed resistance or high resistance to rice blast and rice false smut,among them,13 of them such as Chenghui 3203,MR183-2,R650 and so on were high resistant to neck blast and rice false smut,these resources are of high value for breeding rice blast resistance and rice false smut in Sichuan.(3)Genetic Background Analysis of Resistance to Rice BlastThirty-seven resistant strains were identified by using molecular markers of useful blast resistance genes Pik~h,Pik~m,Pi9,Pi2 and the newly cloned broad-spectrum blast resistance gene Pigm.The results show that,they own each 20 resistant sources which containing Pigm,Pik~h,Pik~m have the same PCR amplification of the purpose of bands as the contrast,there are 14 resistant sources as Yahui 2115,Huazhan and Wushanmiao,which containing Pi2 have the same PCR amplification of the purpose of bands as the contrast;there are 2 resistant sources which containing Pi9 have the same PCR amplification of the purpose of bands as the contrast;there are 16 resistant sources both have the same PCR amplification of the purpose of bands as the contrast at the Piz locus and the Pik locus,accounting for 43.24%of the test source.Thus it can be seen,the blast resistance gene at Pi-z and Pi-k loci were widely distributed in the resistant source,the polymerization of effective genes against these two loci is beneficial to breeding new varieties of rice blast resistance in Sichuan.(4)Identification of Blast Resistance Genes in Yahui 2115By analyzing the data of whole genome resequencing of Yahui 2115,we found 5NBS-LRR genes which may play a role in rice blast resistance;Analysis of qRT-PCR results after inoculation with Magnaporthe grisea showed that,only the LOC_Os11g44960gene was induced to be up-regulated in the Yahui 2115 and the local level was high.Transgenic technology is used to connect LOC_Os11g44960 gene to pCAMBIA1300carrier with 35S as promoter,over expression of LOC_Os11g44960 gene in susceptible material TP309,16 positive strains were obtained by Hygromycin identification,specific primers PCR amplification identification and qRT-PCR identification.The results of the positive strains were inoculated with Magnaporthe grisea showed that,the expression level of LOC_Os11g4496 gene in over expressing strains increased significantly,and the lesion area was also less than that of control,it indicated that the LOC_Os11g4496 gene enhanced rice resistance to rice blast.It can be seen that the LOC_Os11g4496 gene contributes to the resistance of Yahui 2115 to its blast resistance.(5)Genetic Improvement of Yahui 2115Take Yahui2115 as the core germplasm resource,the technical route of"accurate identification of resistance,shuttle breeding from north to south,combining ability of middle and low generations and determination of rice quality"was adopted,we have created 10 new restorers,including Yahui 2116,Yahui 2119,Yahui 2275 and so on.At the same time,23 new hybrid rice combinations were selected to take part in provincial and national regional trials,among them,Ya You 2116 passed the national level approval in2018,The breeding of these new parents and new combinations is of great significance for ensuring the quality,high yield and stable yield of rice.