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Ecology and Epidemiology

Variation in Pathogenicity of Some Indian Isolates of Xanthomonas campestris pv. oryzae. Akshey K. Gupta, Senior geneticist, Department of Genetics, Punjab Agricultural University, Ludhiana, India; S. C. Sharma(2), and R. G. Saini(3). (2)(3)Assistant plant pathologist, and geneticist, respectively, Department of Genetics, Punjab Agricultural University, Ludhiana, India. Phytopathology 76:881-883. Accepted for publication 18 February 1986. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/Phyto-76-881.

Pathogenicity of 13 isolates of Xanthomonas campestris pv. oryzae was tested using 13 rice cultivars and lines. All the isolates were virulent on two International Rice Research Institute (IRRI) differentials, IR 20 (Xa-4) and IR 1545-339 (xa-5), and two Japanese differentials, Tetep (Xa-1, Xa-2) and Java 14 (Xa-1, Xa-3, Xa-Kg), showing that these six resistance genes are of little practical value in resistance breeding in northwestern India. Based on the reactions on a set of nine cultivars and lines, DV 85 (xa-5, Xa-7), CAS 209 (Xa-10), and IR 1160-8-6-1 from IRRI; Kinmaze, Kogyoku (Xa-1, Xa-3, Xa-Kg), and Wase Aikoku 3 (Xa-3) from Japan; and three Indian breeding lines, B76, ARC 10464, and CNGS 20083, 11 different pathotypes were identified. These pathotypes have different virulences as compared to those reported from Japan and Philippines. Additional unidentified resistance genes were observed in seven differentials including Kogyoku, Kinmaze, and Wase Aikoku 3.