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Variation in Pathogenicity and Virulence of Strains of Xanthomonas campestris pv. glycines , the Incitant of Bacterial Pustule of Soybean
Author(s) -
Hokawat S.,
Rudolph K.
Publication year - 1991
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.1439-0434.1991.tb04573.x
Subject(s) - virulence , biology , xanthomonas campestris , inoculation , microbiology and biotechnology , pathogen , pathogenicity , bacteria , xanthomonas , agar plate , agar , horticulture , gene , genetics
Standardized methods were developed to determine the pathogenicity and the degree of virulence of Xanthomonas campestris pv. glycines (Xcg) as well as the reaction of soybean plants in the greenhouse. A glass atomizer is described which allowed uniform inoculation without damaging the leaves. Optimum bacterial concentration was determined as 6 × 10 6 CFU/ml for the pathogenicity test and 1.3 × 10 5 CFU/ml for the virulence test. A total of 64 isolates were tested. Forty‐five strains were designated as pathogenic, six of which were considered highly virulent. It was shown, for the first time, that large differences in the virulence of Xcg strains exist. All the highly virulent strains of Xcg were fresh isolates from diseased soybean leaves collected in Thailand. On the other hand, all the “old” cultures from bacterial collections possessed a low or very low virulence. Decrease of virulence of the pathogen did not occur very fast, however, that is: not within 2 years when stored on YDC‐agar slants. Therefore, the bacteria may be kept on slants at 15 °C for short time storage, but the strains should be preserved permanently as lyophilized cultures.