IDENTIFICATION AND BREEDING-BEHAVIOR OF A MAJOR DELETION OF CHROMOSOME 5D OF TRITICUM-AESTIVUM

A study was undertaken to evaluate the breeding behaviour and to ident ify a spontaneously produced putative chromosomal deletion in the wint er wheat (Triticum aestivum L. em. Thell.) cv Norstar. Male and female transmission studies of plants heterozygous for the deletion chromoso me indicated 9.5% and 48.8% transmission through the pollen and the eg g, respectively. Meiotic analyses of progeny from deletion heterozygot es indicated that the deletion chromosome was eliminated from half of the plants, which agreed with the male and female transmission frequen cies. Testcrosses of the deletion chromosome with telocentrics and nul lisomic-tetrasomic combinations suggested that the deletion involved t he long arm of chromosome 5D. This was confirmed by restriction fragme nt length polymorphism (RFLP) analysis. Also, monosomic plants obtaine d in progeny of deletion heterozygotes were shown to be monosomic for 5D. Studies of plants homozygous for the deletion showed relatively no rmal pairing between the deletion chromosomes, and with the short arm (5DS), but not the long arm (5DL). Deletion homozygotes were self-ster ile, and morphologically similar to plants nullisomic for 5D, but plan ts that also contained 5DL, or a homoeologous chromosome were self-fer tile and had normal morphology. Studies of chromosome morphology indic ated that the deletion chromosome was metacentric, and the length of t he long arm was reduced by approximately 60%. RFLP studies showed that , in terms of genetic distance, 90% of the arm was missing.