A genetic linkage map in autotetraploid lucerne adapted to northern Australia, and use of the map to identify DNA markers linked to resistance to Phytophthora medicaginis

Musial, J. M., Aitken, K. S., Mackie, J. M. and Irwin, J. A. G. (2005) A genetic linkage map in autotetraploid lucerne adapted to northern Australia, and use of the map to identify DNA markers linked to resistance to Phytophthora medicaginis. Australian Journal of Agricultural Research, 56 4: 333-344. doi:10.1071/AR04317


Author Musial, J. M.
Aitken, K. S.
Mackie, J. M.
Irwin, J. A. G.
Title A genetic linkage map in autotetraploid lucerne adapted to northern Australia, and use of the map to identify DNA markers linked to resistance to Phytophthora medicaginis
Journal name Australian Journal of Agricultural Research   Check publisher's open access policy
ISSN 0004-9409
Publication date 2005
Sub-type Article (original research)
DOI 10.1071/AR04317
Volume 56
Issue 4
Start page 333
End page 344
Total pages 12
Editor J. Fegent
Place of publication Collingwood
Publisher CSIRO Publishing
Collection year 2005
Language eng
Subject C1
300203 Plant Improvement (Selection, Breeding and Genetic Engineering)
630502 Pasture, browse and fodder crops
Abstract Phytophthora root rot, caused by Phytophthora medicaginis, is a major limitation to lucerne ( Medicago sativa L.) production in Australia and North America. Quantitative trait loci (QTLs) involved in resistance to P. medicaginis were identified in a lucerne backcross population of 120 individuals. A genetic linkage map was constructed for tetraploid lucerne using 50 RAPD ( randomly amplified polymorphic DNA), 104 AFLP (amplified fragment length polymorphism) markers, and one SSR ( simple sequence repeat or microsatellite) marker, which originated from the resistant parent (W116); 13 markers remain unlinked. The linkage map contains 18 linkage groups covering 2136.5 cM, with an average distance of 15.0 cM between markers. Four of the linkage groups contained only either 2 or 3 markers. Using duplex markers and repulsion phase linkages the map condensed to 7 homology groups and 2 unassigned linkage groups. Three regions located on linkage groups 2, 14, and 18, were identified as associated with root reaction and the QTLs explained 6 - 15% of the phenotypic variation. The research also indicates that different resistance QTLs are involved in conferring resistance in different organs. Two QTLs were identified as associated with disease resistance expressed after inoculation of detached leaves. The marker, W11-2 on group 18, identified as associated with root reaction, contributed 7% of the phenotypic variation in leaf response in our population. This marker appears to be linked to a QTL encoding a resistance factor contributing to both root and leaf reaction. One other QTL, not identified as associated with root reaction, was positioned on group 1 and contributed to 6% of the variation. This genetic linkage map provides an entry point for future molecular-based improvement of lucerne in Australia, and markers linked to the QTLs we have reported should be useful for marker-assisted selection for partial resistance to P. medicaginis in lucerne.
Keyword Agriculture, Multidisciplinary
Alfalfa
Sdrf
Disease Resistance
Molecular Markers
Qtl Mapping
Diploid Alfalfa
Tetraploid Alfalfa
Root-rot
Rflp
Inheritance
Megasperma
Truncatula
Sativa
Aflp
Colinearity
Q-Index Code C1

 
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