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Population Dynamics of Virulence Genes of Xanthomonas campestris pv. malvacearum on Cotton
Author(s) -
Duttamajumder S. K.,
Verma J. P.
Publication year - 1994
Publication title -
journal of phytopathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 60
eISSN - 1439-0434
pISSN - 0931-1785
DOI - 10.1111/j.1439-0434.1994.tb00186.x
Subject(s) - biology , virulence , genotype , xanthomonas campestris , population , gene , pathogen , race (biology) , xanthomonas , xanthomonas campestris pv. campestris , genetics , botany , demography , sociology
Population genetic principles in relation to the pathogenicity genes have been applied on the genotypes (races) of Xanthomonas campestris pv. malvacearum(Xcm) which are characterized on the basis of bacterial blight resistant host genes ( B ‐genes) attacked. Observed (OF) and expected (EF) frequencies were determined to predict the intensity of selection pressure operating in the pathogen population due to the introduction of particular host resistant gene(s). Race 32 (V p , V 7 V 2 V 10 V N ) was the most prevalent genotype representing 41.55% of the Xcm population. Other prevalent genotypes were race 30 (11.08%, V p V 2 V in V N ), race 20 (8.56%, V p V 2 V N ), race 9 (6.80%, V p V in ) and race 8 (11.59%, V p V 2 ). The OF (observed frequency) of race 32 was 41.55%, whereas EF (expected frequency) was 15.74% indicating a strong selection pressure favouring this highly virulent genotype. Whereas, race 31 (V 7 V 2 V in V N ) also overcomes four major genes like race 32 but not the polygene complex, it was less fit and possessed low EF and OF, i.e. 0.25% and 1.18% respectively. Xcm genotypes capable of attacking 3–4 major B ‐genes were prevalent on G. hirsutum , while genotypes with virulence against 1–2 B ‐genes favoured G. barbadense cottons. High virulence level in pathogen genotypes, was maintained on resistant/tolerant host genotypes of G. arboreum and G. hirsutum whereas, it was diluted on the highly susceptible G. barbadense.