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Genetics

Virulence in Puccinia coronata f. sp. avenae and P. graminis f. sp. avenae in New Zealand. J. W. Martens, Plant Pathologist, Agriculture Canada, Research Station, 195 Dafoe Road, Winnipeg, Canada R3T 2M9; P. A. Burnett(2), and G. M. Wright(3). (2)(3)Plant Pathologist and Plant Breeder, respectively, Dept. of Scientific and Industrial Research, Crop Res. Div., Private Bag, Christchurch, N. Z. Phytopathology 67:1519-1521. Accepted for publication 24 May 1977. Copyright © 1977 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-67-1519.

Virulence in the Puccinia coronata population on oats in New Zealand was studied using as differentials: 12 single Pc-gene lines: the International Differential Set: and local cultivars and selections. Sixteen virulence combinations were determined from 93 isolates: most isolates carried apparently unnecessary and not-selected-for virulence on a number of genes for resistance that are not known to have occurred in New Zealand. The rust populations on the North and South Islands had different frequencies of genes for virulence. In contrast, the single Pg-gene lines differentiated only three virulence combinations in Puccinia graminis and no virulence was observed on lines with Pg 1, 2, 4, 8, or 13 even though genes Pg 2 and 4 have occurred in the host population for a long time. Puccinia graminis from oats was also virulent on some cultivars of barley.