RFLP ANALYSIS OF AN AEGILOPS VENTRICOSA CHROMOSOME THAT CARRIES A GENE CONFERRING RESISTANCE TO LEAF RUST (PUCCINIA-RECONDITA) WHEN TRANSFERRED TO HEXAPLOID WHEAT

RFLP analysis has been used to characterise XM(v), a chromosome of Aeg ilops ventricosa present in a disomic addition line of wheat. This chr omosome is known to carry a major gene conferring resistance to leaf r ust (Lr). The analysis demonstrated that XM(v) is translocated with re spect to the standard wheat genome, and consists of a segment of the s hort arm of homoeologous group 2 attached to a group 6 chromosome lack ing a distal part of the short arm. Lr was located to the region of XM (v) with homoeology to 2S by analysis of a leaf rust-susceptible delet ion line that was found to lack the entire 2S segment. Confirmation an d refinement of the location of Lr was obtained by analysis of a spont aneous resistant translocation in which a small part of XM(v) had been transferred to wheat chromosome 2A.