VIEW ARTICLE

Reaction of F₂ Seedlings of Several Crosses of Susceptible and Resistant Wheat Selections to Puccinia striiformis. R. E. Allan, Geneticist, Crops Research Division, ARS, USDA, Pullman, Washington 99163; L. H. Purdy, Former Plant Pathologist, Crops Research Division, ARS, USDA, Pullman, Washington 99163, Present address: Department of Plant Pathology, University of Florida, Gainesville 32601. Phytopathology 60:1368-1372. Accepted for publication 7 April 1970. DOI: 10.1094/Phyto-60-1368.

We classified F₂ progeny of crosses among nine sources of wheat (Triticum aestivum) with seedling resistance (Nord, Spaldings Prolific, Holzapfel Fruh, Rouge Prolifique Barbu, Heines Kolben, Ottawa/Renacimiento, Alba, P.I. 178383, and Suwon 92/3* Omar, 63301) and two seedling-susceptible selections (Omar and Gaines) for reaction to a culture of Puccinia striiformis. We also studied certain crosses among the nine seedling resistant sources. Pre- and postinoculation temp were 15 ± 2 C. In general, crosses of resistant parents with Omar produced higher proportions of plants in the resistant classes than crosses with Gaines. Resistant × susceptible crosses demonstrated monogenic control of reaction with P.I. 178383, Spaldings Prolific, and Sel.63301, whereas digenic control prevailed with Nord, Holzapfel Fruh, and Ottawa/Renacimiento. Eight resistant × resistant crosses indicated digenic control, but the crosses Nord/Spaldings Prolific, Nord//Ottawa/Renacimiento, P.I. 178383//Ottawa/Renacimiento, Nord/Rouge Prolifique Barbu, and P.I. 178383/Alba gave trigenic reaction patterns. No suitable interpretation could be made of the reaction pattern of the Sel.63301//Ottawa/Renacimiento cross. Evidence suggests that Nord, Heines Kolben, and P.I. 178383 have in common at least one gene that governs an intermediate reaction type.