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 potent ial 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 u sing total genomic DNA, from H. villosa in the presence of unlabelled wheat DNA, confirmed that Add 6V-1 is a disomic wheat-H. villosa chrom osome 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 c hromosome from H. villosa through Robertsonian fusion of misdivided ce ntromeres. Only the short arm of the group 6 chromosome of H. villosa was involved in the genetic control of mite resistance, a conclusion b ased on the genomic in situ hybridization signal and specific DNA frag ments obtained by polymerase chain reaction.