Inheritance of seedling resistance to stripe rust (Puccinia striiformisf. sp.tritici) in ‘Otane’ and ‘Tiritea’ wheat (Triticum aestivum)

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Abstract
Two spring wheat (Triticum aestivum) cultivars, ‘Tiritea’ and ‘Otane’, were crossed and the reactions of the F1‐derived double haploid (DH) population to the stripe rust pathogen (Puccinia striiformis f. sp. tritici) at the seedling stage were examined in glasshouse and field experiments. Both parental cultivars were susceptible to stripe rust pathotype 106E139A+, buttransgressive segregation in the DH progenies indicated that both parents possess resistance genes. The distribution of DH lines fitted a trigenic ratio with epistatic gene action. In a proposed model, resistant DH lines were produced when all three loci involved were homozygous recessive, moderately resistant DH lines were produced when the t gene was homozygous recessive with at least one recessive allele at either the B or the C locus, and susceptible DH lines were produced when either t, b, or c were present alone or had a dominant gene at the B and the C loci. The susceptible phenotype of all F1 progenies indicated that the resistance factors segregated were all recessive. The susceptible reaction of both cultivars could be attributed to the presence of genes that may suppress the expression of resistance genes when they coexist in the parents. The use of these cultivars as parents in different wheat breeding strategies is briefly discussed.