| dc.description.abstract | An investigation of the suppression effect of Pc38 on Pc94 was conducted by developing F2 segregating populations from genotypes possessing Pc38 and Pc94, together with a population void of the Pc38. Segregating phenotypic ratios were used to determine the crown rust resistance suppression at the Pc38 locus. A Leggett/Df-38 F2 population, possessing no Pc38 gene, produced resistant to susceptible ratios of 3:1 and 2:1. Leggett/Dumont and Leggett/Steele population possessing a copy of Pc38 each, produced resistant to susceptible ratios of 1:3, 1:2 and 3:13. Leggett was the resistant parent possessing Pc94 while Dumont and Steele were the susceptible parents possessing Pc38. Df-38, a susceptible parent, contained neither Pc94 nor Pc38. CR91 was used to identify resistant and susceptible plants in the segregating populations. A factor closely linked to Pc38 or the gene itself was confirmed to suppress the resistance effect of Pc94 in this study. A second experiment was conducted to determine the allelic relationship of crown rust resistance genes in 08BT26-2, 08BT70-1, BT1020-1-1 and BT1021-1-1. The genotypes possessed resistance genes introgressed from A. strigosa similar to Leggett. Leggett is homozygous for Pc94. Four different F2 segregating populations were developed from Leggett by 08BT26-2, 08BT70-1, BT1020-1-1 and BT1021-1-1. A crown rust race virulent to Pc94 was used to determine resistant to susceptible ratios of the populations. Crown rust race 16MN (100- 3) was used to discriminate between resistant and susceptible plants. The allelism test confirmed that the resistance gene present in 08BT26-2 and 08BT70-1 genotypes were the same as Pc94 in Leggett while genotypes BT1020-1-1 and BT1021-1-1 were different. | en_US |
