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Phenotypic association of adult-plant resistance to leaf and stripe rusts in wheat

Navabi, A., Singh, R.P., Huerta-Espino, J., Tewari, J.P.
Canadian journal of plant pathology 2005 v.27 no.3 pp. 396-403
rust diseases, phenotype, genetic resistance, pleiotropy, linkage groups, wheat, Triticum aestivum, plant pathogenic fungi, disease resistance, genes, Puccinia recondita, Puccinia striiformis, leaves
Association of resistance to multiple diseases is of interest to plant breeders as it simplifies the breeding process. Phenotypic association of adult-plant resistance to leaf and stripe rusts, caused by Puccinia triticina and Puccinia striiformis f. sp. tritici, respectively, was studied in F5 wheat lines derived from a diallel cross involving one susceptible and five resistant genotypes. Resistance in the parental genotypes was formerly identified as being conditioned by the Lr34/Yr18 linkage on chromosome arm 7DS, in addition to at least two to three genes with additive effects. Adult-plant resistance to leaf rust was found to be closely associated with resistance to stripe rust in the wheat genotypes examined in this study. Results indicated that genes other than Lr34/Yr18 were also either linked or pleiotropic for resistance to both diseases. This linkage or pleiotropic effect, however, did not seem to occur in every instance. Resistance genes other than Lr34/Yr18 were estimated to have contributed to 40% and 43% reductions in severity of leaf and stripe rusts, respectively, while lines with a phenotype of leaf-tip necrosishad, on average, 30.5% and 20.8% less severity for leaf and stripe rusts, respectively.