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Resistance

Haustorium Formation by Puccinia hordei in Leaves of Hypersensitive, Partially Resistant, and Nonhost Plant Genotypes. R. E. Niks, Institute of Plant Breeding, Agricultural University, Lawickse Allee 166, 6709 DB Wageningen, the Netherlands, Present address: ICARDA, P.O. Box 5466, Aleppo, Syria; Phytopathology 73:64-66. Accepted for publication 21 May 1982. Copyright 1983 The American Phytopathological Society. DOI: 10.1094/Phyto-73-64.

In barley genotypes with early acting hypersensitivity or with partial resistance and in nonhost species like wheat, a large proportion of the colonies of Puccinia hordei aborted after the formation of the first infection hyphae and a few haustorial mother cells. The early abortion without collapse of plant cells was associated with a failure in the formation of haustoria. This was particularly evident in partially resistant barley. Early abortion with host cell necrosis occurred after the formation of the first haustoria. This type of abortion was important in barley with the early acting Pa3 gene for hypersensitivity. In nonhost wheat, most of the infection units aborted before the formation of the first haustorium.