Identification of QTL for resistance and susceptibility to <Emphasis Type="Italic">Stagonospora meliloti</Emphasis> in autotetraploid lucerne |
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Authors: | J M Musial J M Mackie D J Armour H T T Phan S E Ellwood K S Aitken J A G Irwin |
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Institution: | (1) School of Integrative Biology, The University of Queensland, Brisbane, QLD, 4072, Australia;(2) Australian Centre for Necrotrophic Fungal Pathogens, State Agricultural Biotechnology Centre, Health Sciences, Murdoch University, Perth, WA, 6150, Australia;(3) CSIRO Plant Industry, Queensland Bioscience Precinct, St Lucia, QLD, 4067, Australia |
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Abstract: | In eastern Australia and California, USA, one of the major lethal fungal diseases of lucerne (Medicago sativa) is Stagonospora root and crown rot, caused by Stagonospora meliloti. Quantitative trait loci (QTL) involved in resistance and susceptibility to S. meliloti were identified in an autotetraploid lucerne backcross population of 145 individuals. Using regression analysis and interval
mapping, we detected one region each on linkage groups 2, 6 and 7 that were consistently associated with disease reaction
to S. meliloti in two separate experiments. The largest QTL on linkage group 7, which is associated with resistance to S. meliloti, contributed up to 17% of the phenotypic variation. The QTL located on linkage group 2, which is potentially a resistance
allele in repulsion to the markers for susceptibility to S. meliloti, contributed up to 8% of the phenotypic variation. The QTL located on linkage group 6, which is associated with susceptibility
to S. meliloti, contributed up to 16% of the phenotypic variation. A further two unlinked markers contributed 5 and 8% of the phenotypic
variation, and were detected in only one experiment. A total of 517 simple sequence repeat (SSR) markers from Medicago truncatula were screened on the parents of the mapping population. Only 27 (6%) SSR markers were polymorphic and could be incorporated
into the autotetraploid map of M. sativa. This allowed alignment of our M. sativa linkage map with published M. truncatula maps. The markers linked to the QTL we have reported will be useful for marker assisted selection for partial resistance
to S. meliloti in lucerne. |
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Keywords: | Alfalfa Molecular markers QTL mapping |
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