Genetic induction of chromosomal rearrangements in barley chromosome 7H added to common wheat

Chromosome 2C of Aegilops cylindrica induces chromosomal rearrangements in alien chromosome addition lines, as well as in euploid lines, of common whe at. To induce chromosomal rearrangements in barley chromosome 7H, reciproca l crosses were made between a mutation-inducing common wheat line that carr ies a pair of 7H chromosomes and one 2C chromosome and a 7H disomic additio n line of common wheat. Many shrivelled seeds were included in the progeny, which was an indication of the occurrence of chromosome mutations. The chr omosomal constitution of the viable progeny was examined by FISH (fluoresce nce in situ hybridization) using the barley subterminal repeat HvT01 as a p robe. Structural changes of chromosome 7H were found in about 15% of the pr ogeny of the reciprocal crosses. The aberrant 7H chromosomes were character ized by a combination of N-banding, FISH and ge nomic in situ hybridization . Mosaicism for aberrant 7H chromosomes was observed in seven plants. Tn to tal, 89 aberrant 7H chromosomes were identified in 82 plants, seven of whic h had double aberrations. More than half of the plants carried a simple del etion: four short-arm telosomes, one long-arm telosome, and 45 terminal del etions (23 in the short arm, 21 in the long arm, and one involving both arm s). About 40% of the aberrations represented translocations between 7H and wheat chromosomes. Twenty of the translocations had wheat centromeres, 12 t he 7H centromere, with translocation points in the 7HS (five) and in the 7H L (seven), and the remaining four were of Robertsonian type, three involvin g 7HS and one with 7HL. In addition, one translocation had a barley segment in an intercalary position of a wheat chromosome, and two were dicentric. The breakpoints of these aberrations were distributed along the entire leng th of chromosome 7H.