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Resistance

Mutations to Virulence and Avirulence in Melampsora lini. G. D. Statler, Department of Plant Pathology, North Dakota State University, Fargo 58105; Phytopathology 75:771-773. Accepted for publication 25 January 1985. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/Phyto-75-771.

A culture of race 1 of Melampsora lini was crossed with a culture of race 400 to produce a culture heterozygous at several loci. Flax plants inoculated with the heterozygous culture were treated with a solution of NTG (N-methyl-N'-nitro-N-nitrosoguanidine) to induce mutations in M. lini. Isolations were made from compatible infection sites on near-isogenic lines resistant to the culture used. Seven mutant cultures were isolated that were virulent at the A_L¹¹, A_L⁸, A_M⁵, and/or A_N² loci after NTG treatment. Three were virulent at A_L¹¹, three were virulent at A_L⁸, A_M⁵, and A_N², and one was virulent on A_L⁸ and A_N² after NTG treatment. Nine mutant cultures were avirulent at the A_L¹, A_L¹⁰, and/or A_M² loci after NTG treatment. Three were avirulent at the A_L¹ and A_L¹⁰ loci, one was avirulent at the A_L¹⁰ and A_M² loci, two at A_L¹⁰, and three at the A_M² locus after NTG treatment.