Molecular characterization of Haynaldia villosa chromatin in wheat lines carrying resistance to wheat curl mite colonization.

Wheat-Haynaldia villosa (L.) Schur, hybrid lines were tested as potential sources of resistance to colonization by the wheat curl mite, the vector of wheat streak mosaic virus. Two lines, Add 6V-1 and Sub 6V-1, were found to be mite-resistant. Fluorescence in situ hybridization using total genomic DNA, from H. villosa in the presence of unlabelled wheat DNA, confirmed that Add 6V-1 is a disomic wheat-H. villosa chromosome addition line. Sub 6V-1 turned out to be a homoeologous wheat-H. villosa chromosome translocation line rather than a substitution. The translocation in Sub 6V-1 occurred between a wheat chromosome and a chromosome from H. villosa through Robertsonian fusion of misdivided centromeres. Only the short arm of the group 6 chromosome of H. villosa was involved in the genetic control of mite resistance, a conclusion based on the genomic in situ hybridization signal and specific DNA fragments obtained by polymerase chain reaction.