Evaluation Of Resistance To Main Rice Varieties In Heilongjiang Province And Analysis Of Avirulence Genes Of Magnaporthe Grisea

Rice blast is one of the main diseases threatening rice yield in Heilongjiang Province.Breeding and utilization of resistant varieties is the most effective measure for controlling rice blast.However,due to the variety of physiological traits of rice blast fungus and their susceptibility to mutation,rice varieties are promoted.After 5 years,the resistance was gradually “lost”.In this study,some rice cultivars in Heilongjiang Province were comprehensively evaluated by seedling vaccination,and combined with the results of molecular markers of rice blast resistance gene,the combination of high-quality resistance genes was screened for cultivation.The theoretical basis for the resistance to rice blast.At the same time,the detection and analysis of the non-toxic genotypes of rice blast fungus in Heilongjiang Province were carried out,which provided a theoretical basis for the rational layout of rice varieties.The specific research results are as follows:1.34 main rice varieties in Heilongjiang Province were selected and evaluated for resistance by artificial inoculation in seedling stage.The results showed that the resistance frequency of Longjing 53 was the highest,being 94.3%,and that of Longjing 46 was the lowest,being 25.4%.The comprehensive Resistance evaluation showed that the disease-resistant(R)varieties accounted for 29.4% of the tested materials;the comprehensive Resistance evaluation of the medium-resistance(MR)varieties accounted for 64.7% of the tested materials;the comprehensive Resistance evaluation was medium-sensitivity(MS)and susceptible(S)Each of the varieties accounted for 2.9% of the tested materials.This result indicates that there are high-quality anti-source materials in the germplasm resources of Heilongjiang Province.2.Using the functional markers of six rice blast resistance genes Pita,Pib,Pikm,Pi9,Pii and Pid3,34 rice varieties were tested for molecular markers.The results showed that the distribution frequency of Pi9 was the highest in the tested varieties,followed by Pita and Pikm,the distribution frequency of Pib and Pii was lower,and the distribution frequency of Pid3 was the lowest.Among the 34 rice materials tested,the same variety was detected to contain up to 5 resistance genes,and at least one resistance gene was included.The species with 2 resistance genes accounted for the largest proportion.Longjing 40 and Longjing 42 does not contain the gene to be detected.The resistance gene detection results combined with the resistance performance of the varieties showed that the rice varieties containing the gene combinations Pita,Pib and Pita,Pi9 and Pikm showed better resistance.3.The test used 299 rice blast strains isolated from 6 species in Heilongjiang Province in 2013,2015 and 2017,and tested 5 virulence genes,which were clear and non-toxic.Gene distribution and interannual trends,and selected some strains to analyze the variation.The results showed that the frequency of Avr-pik was the highest,the frequency of Avr-pia was the lowest,and the frequency of the two avirulence genes did not change significantly during the interannual period.Avr Piz-t and Avr-pib are widely distributed avirulent genotypes in Heilongjiang Province.The frequency of Avr Piz-t is increasing year by year,and Avr-pib is basically flat after rising.The distribution frequency of Avr-pi9 is slightly lower,and it gradually decreases during the inter-annual period.There were also differences in the distribution of avirulence genes among test strains in different years and regions.Through sequencing results,three variant types of avirulence gene Avr-pib,two variant types of Avr-pi9 and three variant types of Avr Piz-t were found in Heilongjiang Province.Avr-pia is the most stable and non-toxic gene type,and there is no mutation in the test year;Avr-pik has the most abundant allele types,and six variant types are detected in the experiment,among which Avr-pik-B,-C,-D are mostly.This study newly discovered a variant of the type Avr-pik-K,which has four base mutations,136(C / A),139(C / G),143(G / A)and 233(T / A),In 2017,Tonghe County,Qing'an County and Tangyuan County of Heilongjiang Province existed.The transposon insertion of one of the variant types was detected.It was found that the insertion of the transposon(Pot3)in the avirulence gene Avr Piz-t of Heilongjiang Province showed that the avirulence gene mutation type of Magnaporthe grisea in Heilongjiang was very rich.