Retrotransposon-based molecular markers for linkage and genetic diversity analysis in wheat.
Retrotransposon-based molecular markers have been developed to study bread wheat ( Triticum aestivum) and its wild relatives. SSAP (Sequence-Specific Amplification Polymorphism) markers based on the BARE-1/ Wis-2-1A retrotransposons were assigned to T. aestivum chromosomes by scoring nullisomic-tetrasomic chromosome substitution lines. The markers are distributed among all wheat chromosomes, with the lowest proportion being assigned the D wheat genome. SSAP markers for BARE-1/ Wis-2-1A and three other wheat retrotransposons, Thv19, Tagermina and Tar1, are broadly distributed on a wheat linkage map. Polymorphism levels associated with these four retrotransposons vary, with BARE-1/ Wis-2-1A and Thv19 both showing approximately 13% of bands polymorphic in a mapping population, Tagermina showing approximately 17% SSAP band polymorphism and Tar1 roughly 18%. This suggests that Tagermina and Tar1 have been more transpositionally active in the recent evolutionary past, and are potentially the more useful source of molecular markers in wheat. Lastly, BARE-1 / Wis-2-1A markers have also been used to characterise the genetic diversity among a set of 35 diploid and tetraploid wheat species including 26 Aegilops and 9 Triticum accessions. The SSAP-based diversity tree for Aegilops species agrees well with current classifications, though the Triticum tree shows several significant differences, which may be associated with polyploidy in this genus.
Queen
R A
RA
Plant Research Unit, University of Dundee at SCRI, Invergowrie, Dundee DD2 5DA, Scotland, UK.
Gribbon
B M
BM
James
C
C
Jack
P
P
Flavell
A J
AJ
D018744:DNA, Plant / Q000235:genetics; D008040:Genetic Linkage; D005819:Genetic Markers; D014644:Genetic Variation; D010802:Phylogeny; D011110:Polymorphism, Genetic; D018626:Retroelements / Q000235:genetics*; D013045:Species Specificity; D014908:Triticum / Q000235:genetics*
D018744:DNA, Plant; D005819:Genetic Markers; D018626:Retroelements