Genetic analysis of wheat rust resistance genes segregating in a Kariega x Avocet S population

Abstract

Complete adult plant resistance (APR) to stripe rust of the wheat cultivar Kariega was previously ascribed to two major quantitative trait loci (QTL) on chromosomes 2B and 7D and three minor QTL. In the present study the Kariega x Avocet S doubled haploid population was increased from 150 to 254 individuals and the map improved by adding Diversity Array Technology (DArT) markers. Additional field and greenhouse phenotypic data for stripe rust were collected. The major QTL regions detected previously were validated, but different minor QTL compared to the previous study were identified. In the field, the chromosome 2B QTL region explained more of the phenotypic variance for host reaction type scores (RT), compared to the 7D QTL region. For the field leaf area infected score (LAI) both the major QTL regions explained more variance over time. A minor QTL on chromosome 4A of Kariega was consistently detected for LAI (up to 25.9%) and the two early RT (up to 12.2%) scores. In addition we used an accelerated greenhouse scoring method for APR to stripe rust, which detected both major QTL, the 4A QTL and another minor QTL. Using an adult plant screening method and different pathotypes of Puccinia triticina, several leaf rust resistance genes have been detected in the mapping population. This study has been valuable in confirming and expanding information on the leaf rust resistance genes and QTL for adult plant resistance to stripe rust in wheat

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