VIEW ARTICLE

Disease Detection and Losses

A Comparison of Isozymes of Phakopsora pachyrhizi from the Eastern Hemisphere and the New World. M. R. Bonde, Research plant pathologist, U.S. Department of Agriculture, Agricultural Research Service, Foreign Disease-Weed Science Research, Building 1301, Fort Detrick, Frederick, MD 21701; G. L. Peterson, and W. M. Dowler. Biological laboratory technician, and research plant pathologist, respectively, U.S. Department of Agriculture, Agricultural Research Service, Foreign Disease-Weed Science Research, Building 1301, Fort Detrick, Frederick, MD 21701. Phytopathology 78:1491-1494. Accepted for publication 13 July 1988. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1988. DOI: 10.1094/Phyto-78-1491.

Eleven isolates of Phakopsora pachyrhizi from widely separated areas of Asia and Australia were compared by means of isozyme analysis with one isolate from Puerto Rico and three from Brazil. No differences in isozyme banding patterns were detected among any of the isolates from Asia and Australia, and no differences were detected among any of the four isolates from the New World. However, the maximum coefficient of similarity between isolates from Asia and Australia compared with those from the New World was estimated at 0.07 (7% alleles in common). This low frequency of shared putative alleles indicates that two populations of P. pachyrhizi with distinct isozyme polymorphisms are involved in causing rust on soybean, one in Asia and Australia and another in the New World (Brazil and Puerto Rico).