| The rice blast disease is devastating diseases of rice caused by the fungal pathogenMagnaporthe oryzae and it is major diseases in rice production all over the country.Rice blast has been affecting the rice yield and quality in Liaoning province,so the study of rice blast fungus is closely related to food security.In this paper,the races population dynamics,avirulent genes and rice blast resistance genes of the fungus in Liaoning province were studied,providing the theoretical basis for basis for the prevention and control of rice blast.1.The population dynamics of the races of M.oryzae in Liaoning province for2015-2016.7 kinds of Chinese rice differential host selected were used to identify the 155 M.oryzae isolates and 44 physiological races in 6 groups were divided.ZA and ZB groups were the dominant groups with the frequency of 67.09%.ZF group took the third position of all the groups.ZC,ZD and ZE had a small proportion and remained stable in two years.ZA1,ZB1 and ZF1 were the dominant physiological races.Overall,the relative ratio of strong ability of infection groups ZA,ZB,ZC,ZD as well as weak ability of infection groups ZE,ZF was about 4: 1,suggested that pathogenic ability of the fungus was stronger these two years.The distribution of M.oryzae groups was complex.There were 6 groups in Dandong and Fushun where the most complex groups existed.There were 5 groups in Dalian.Shenyang,Panjin and Tieling had 4 groups similarly.On the other hand,the distribution of Yingkou were simple 3groups.2.The identification and analysis of the avirulent genes of M.oryzae in Liaoning province.One hundred and eighty-four isolates selected between 2014 and 2015 from Liaoning province were tested to identify the nine cloned avirulent genes in the fungus.By sequence analysis the avirulent gene types and distribution of the fungus in Liaoning province were detected.The detection showed that Avr1-CO39,Avr-pia and Avr-pii were not existed in Liaoning province however the Avr-pizt,Avr-pik,Avr-pita,ACE1,Avr-pi9 and Avr-pib existed with different frequency and mutation type.The avirulent gene ACE1 appeared 98.17%(2014)and 100.00%(2015)of the M.oryzae strains tested,it was the most stable avirulent gene and took up the highest proportion from the 8 rice growing regions in Liaoning province between two years.The second avirulent gene Avr-pik appeared 91.74%(2014)and 92.00%(2015),it was tested 6 distinct genotypes of Avr-pik between two years.New genotypes of Avr-pik were found in the isolates from Fengcheng in Dandong,Xinbin in Fushun and Kaiyuan in Tieling named Avr-pik-I(KY432943)and Avr-pik-J(KY432944),the two gene sequences had beenuploaded to NCBI.Avr-pik-D appeared all the cities except for Dandong and Fushun.Avr-pizt was stable wtih the frequency of more than 88.00% between two years.Avr-pi9 had the frequency difference in two years and this gene could not be amplified in M.oryzae strains collected in 2015 from 3 cities in the Liaoning province(Yingkou,Panjin,Tieling).Avr-pita appeared 89.91%(2014)and 76.00%(2015),and 3 distinct genotypes of Avr-pita I,II,V were widely distributed in Liaoning province.Avr-pib appeared the low frequency,compared with2014,the carrying amount and distribution area increased in 2015.3.Identification of rice blast resistance genes in Liaoning ProvinceIn this study,185 cultivars from Liaoning province were used to study nine resistance genes Pi5,Pi36,Pi37,Pib,Pid2,Pid3,Pik,Pikh and Pita.The results showed that Pita appeared 99.46% with the highest proportion.Susceptible gene of Pita took up 17.39% in all cultivars with resistance gene and the protein tertiary structure between susceptible gene and resistance gene were different.Pik appeared the lowest frequency 33.51%.The other resistance genes existed with different frequency.The proportion was 100% when 23 cultivars carried the resistance gene Pi36,Pi37,Pib,Pid2,Pid3,Pik,Pikh and Pita.It was suggested there could be possible synergistic interactions between genetic effect,they worked together to increase the resistance of rice cultivars.4.The rice blast resistant identification of the tested rice varieties in Liaoning(2015-2016)6 kinds of representative and different pathogenicity M.oryzae isolates were selected to identify the resistance of 138 rice varieties that 68 varieties in 2015 and 70 varieties in 2016.Combined the result of seedling stage and the field,the results showed there were 9 high resistant rice varieties with the frequency of 6.52% and 101 resistant varieties with the frequency of 73.19%.There were 21 varieties had middle resistance to M.oryzae with the frequency of 15.22% and 5 varieties had middle sensitive to M.oryzae with the frequency of3.62%.There were only 2 high susceptible rice varieties with the frequency of 1.45%. |
PDF Full Text Request