Morphological and cytological abnormalities in a homozygous interchange in Pisum sativum

Plants homozygous for an interchange in the long arms of chromosomes 3 and 5 were selected from the progeny of translocated heterozygotes through mitotic chromosome analysis. While a deficit of translocated homozygotes was observed in these segregating families, an increase in the proportion of normal plants was obtained. The translocated homozygotes showed a bushy, dwarfed and weak form coupled with nearly complete sterility. Meiosis turned out to be normal except for the presence of anaphase bridges that occurred in about 10 percent of the pollen mother cells. However, vegetative and floral buds degenerated in the majority of cases before pods developed. In mitosis, anaphase bridges were observed. Their frequency was 30 percent and they were formed by only one of the exchanged chromosomes. Such bridges are considered a consequence of the so-called point errors, which are suggested as the main cause of developmental disturbances.