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Host-pathogen interaction in rice-bacterial blight pathosystem

100%

Nayak D., Bose L. K., Reddy P. R., Nayak P.

Journal of Plant Protection Research

2008

tom 48

nr 3

Virulence pattern among 52 isolates of Xanthomonas oryzae pv. oryzae, the causal organism of bacterial blight disease was tested on 16 rice genotypes possessing 11 known Xa genes conferring resistance. Significant differences among the host genotypes as well as the pathogen isolates and in their interaction, suggested that the host genotypes differed in vertical resistance and the pathogen isolates differed in virulence. None of the genotypes exhibited resistant reaction against all the isolates, while one Japanese and two IRRI differentials were knocked down by all the isolates. The set of 16 rice genotypes possessed the Xa genes viz. Xa1, 2, 3, 4, 5, 6, 7, 10, 11, 12 & 13. The isolates carried 4-11 virulence factors, out of a total number of 11 v-factors that could be evaluated from this set of host genotypes to overcome the resistance offered by the corresponding Xa genes. The pattern with virulence to Xa1, 2, 4 & 11 and avirulence to the genes Xa6, 7, 5, 13 & 10 was very common. The wide distribution of the virulence factors over different states of India suggested nonparallelism between virulence pattern and geographical distribution of the isolates. The 52 isolates could be classified into five groups using hierarchical agglomerative method of cluster analysis based on the number of v-factors possessed by each of them viz. 11, 10, 8, 7 & 4, which were equivalent to the pathotype grouping of 1, 4, 7, 14+15 & 16, respectively. The application of the methods of numerical taxonomy emerged as a valuable tool in classification of bacterial isolates into virulence groupings.

Variability in Xanthomonas oryzae pv. oryzae, the incitant of bacterial blight disease of rice

100%

Nayak D., Reddy P. R., Nayak P.

Journal of Plant Protection Research

2009

tom 49

nr 1

15-26

The virulence pattern of 52 bacterial strains of Xanthomonas oryzae pv. oryzae, the causal organism of bacterial blight disease of rice was assessed on 41 rice genotypes including five Japanese and five Philippines' differentials. A significant differential interaction observed among the bacterial isolates, the host-genotypes and in their interaction suggested that the host-genotypes differed in vertical resistance and bacterial isolates differed in virulence. The two Japanese differentials Kinmaze and Rantai Emas and two Philippines' differentials IR 8 and IR 20, exhibited highly susceptible reactions against all the 52 bacterial isolates. Five new Indian differentials were selected, one from each of the five clusters of genotypes obtained through hierarchical method of numerical analysis of the virulence pattern of 52 bacterial isolates on 41 host-genotypes. The 52 bacterial isolates could be grouped into six clusters on the basis of their pathogenicity pattern on five new Indian differentials, which were designated as Pathotype-1, 4, 7, 14, 15 and 16, following a standard computer generated virulence pattern chart. These pathotypes were comparable with the Japanese pathotype groups of I, II, III and IV and Philippines' pathotype groups of I, II, III, IV and V. The most virulent pathotype-1 was distributed over four eastern states of India, namely Andhra Pradesh, Orissa, West Bengal and Bihar. In view of the free exchange of genetic material all over the country, continuous monitoring of the prevalence of new pathotypes with the help of the present set of differentials, will accelerate the resistance breeding programme and help in disease control through introduction of location specific resistant cultivars.

Ograniczanie wyników

2 Journal of Plant Protection Research

2 Nayak D.

2 Nayak P.

2 Reddy P. R.

1 Bose L. K.

1 2009

1 2008

Wyniki wyszukiwania

Host-pathogen interaction in rice-bacterial blight pathosystem

Variability in Xanthomonas oryzae pv. oryzae, the incitant of bacterial blight disease of rice