Inheritance of Resistance to Stem Rust in a Selection of the Wheat Cultivar ‘Waldron’1
- N. D. Williams and
- J. D. Miller2
The hard red spring wheat (Triticum aestivum L.) cultivar ‘Waldron’ is resistant to North American strains of stem rust (Puccinia graminis f. sp. tritici). The inheritance of resistance in a selection of Waldron (Wdr-sel) was studied to determine the number of genes affecting reaction to 15 cultures of the stem rust fungus. F2 plants from Wdr-sell/‘Little Club’ were progeny tested by inoculating families of F3 seedlings. Infection types were used to classify each F2 family into homozygous susceptible (S), segregating resistant and susceptible seedlings in a monogenic ratio (Seg), and inseparable (I). Segregation ratios were tested by chi-square for goodness of fit to ratios of 4n-2n-1 (1):2n(Seg):l(S), where n is the number of segregating genes for resistance. Wdr-sel had one gene for reaction to culture A-14NW (race 29, HNH) and two genes for reaction to cultures 72-14-5 (race 11-32-113, RPQ), 72-41spl (race 15B, TLM), WM-1 (race 18, LBC), Gb121 (race 121, DCM), 370c (race 151, QFL), Or9e (race 9, JBC), Orllc (race 151, QBC), 41-21spl (race 15, TBC), 72.00 (race 11-32-113, RTQ), A-1 (race 151, QSH), A-5 (race 156, MBC; one F1 family), and 75-86spl (race 151, QSH; one F1 family). One F1 family gave trigenic segregations with cultures WM-1, Or9e, Orllc, 41-21sp1, and A-5. Data for reactions to culture A-15 (race 17, HNQ) were a poor fit to a digenic ratio and were inconclusive; however, the data were a better fit to a digenic ratio than to a monogenic or trigenic ratio. Wdr-sel had four genes for resistance to culture 111-SS2 (race 111, LCB).
Paired comparisons of reactions to the different cultures were inconclusive but were consistent with the hypothesis that the gene for resistance to culture A-14NW also conditioned resistance to the other cultures, and that the same two genes conditioned resistance to 13 of the cultures.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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