Homoeologous relationships of Haynaldia villosa chromosomes with those of Triticum aestivum as revealed by RFLP analysis

Homoeologous relationships between Haynaldia villosa chromosomes and bread wheat (Triticum aestivum) were studied in two sets of wheat-H. villosa addi tion lines and five substitution lines by restriction fragment length polym orphism (RFLP) analysis. H. villosa chromosomes 1V to 7V are homoeologous w ith group 1 to 7 chromosomes of wheat. In wheat-H. villosa substitution lin es, the wheat chromosomes 3D, 4D, 5D, and 6A were replaced by homoeologous H. villosa chromosomes. The addition lines for chromosome 4V and 5V from th ree different accessions were analyzed by C-banding, and characterized by R FLP markers. Group 4 and 5 translocations were detected on chromosomes 4V#1 and 5V#1 (produced by Sears, unpublished), and 4V#3 and 5V#3 (produced by Lukaszewski, personal communication). The translocation breakpoints were lo cated between Xpsr1051 and Xpsr115 on 4VL and between Xpsr370 and Xcdo1312 on 5VL. The similarities of the breakpoints within the Triticeae indicates that the specific chromosome regions of the homoeologous groups 4 and 5 are "hot spots" for chromosome breaks. The group-5 homoeologous loci, Xpsr115, Xpsr580, and Xcdo484, also were detected on the chromosome 4V#2 (produced by Liu et al., 1988) with a similar breakpoint between Xpsr1051 and Xpsr115 . However, no reciprocal translocation was detected on the chromosome 5V#2. Possible reasons for difference of 4/5 translocation in this species are d iscussed.