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Genetics

Differentiation of Two Anastomosis Groups of Rhizoctonia solani by Isozyme Analysis. J. P. Laroche, Département de Phytologie, Faculté des Sciences de I’Agriculture et de l’Alimentation, Université Laval, Sainte-Foy, Québec, Canada G1K 7P4; S. H. Jabaji-Hare(2), and P.-M. Charest(3). (2)Department of Plant Science, Macdonald Campus of McGill University, 21,111 Lakeshore Rd., Ste.-Anne-de-Bellevue, Québec, Canada H9X 3V9; (3)Département de Phytologie, Faculté des Sciences de I’Agriculture et de l’Alimentation, Université Laval, Sainte-Foy, Québec, Canada G1K 7P4 Phytopathology 82:1387-1393. Accepted for publication 29 July 1992. Copyright 1992 The American Phytopathological Society. DOI: 10.1094/Phyto-82-1387.

Isozyme electrophoresis was applied to study the genetic relationship between anastomosis groups (AGs) 3 and 9 of Rhizoctonia solani. The banding patterns of seven enzymes were determined by protein polyacrylamide gel electrophoresis. A total of 76 phenotypes were detected for all the enzymes. Diaphorase gave the most polymorphic banding patterns, followed by esterase and malate dehydrogenase. On the basis of principal component analysis and cluster analysis, the isolates were subsequently divided into two dissimilar and genetically distant groups (I and II). These groups are in agreement with previous anastomosis groups 3 and 9. Group I represented all isolates belonging to AG-9. Group II represented all isolates belonging to AG-3 and was subdivided into three subgroups (IIA, IIB, and IIC). Subgroup IIA was made up of two isolates originating from Canada; IIB represented all isolates originating from Japan and Britain; and IIC represented the majority of the North American isolates. No specific relation was found between isozyme phenotype and biogeographical origins of AG-9 isolates. The isozyme results indicate that the anastomosis grouping concept is genetically based.