Spindle sensitivity to colchicine of the Ph1 mutant in common wheat

Abstract

Mitotic spindle sensitivity to colchicine of a common wheat line carrying a mutation at the Ph1 locus which increases homeologous pairing at meiosis, was studied in treated root-tip cells and compared with that of wild type (Ph1/Ph1) and plants deficient for chromosome 5B. Spindle sensitivity was determined by the percentage of fully affected cells of the overall metaphase cell population. The high-pairing mutant (ph1b/ph1b), which is assumed to be a deficiency for the Ph1 locus on the long arm of chromosome 5B, was significantly more sensitive to colchicine than the corresponding control line, i.e., plants carrying the wild-type allele, Ph1. The sensitivty of the mutant was similar to that of plants deficient for chromosome 5B. Spindle sensitivity to colchicine, previously found in plants carrying different doses of chromosomal arm 5BL, may be determined by the Ph1 gene. This gene presumably exerts its effect on the spindle via modification of some microtubular components. Microtubules are a possible target structure for this gene, which is known to affect chromosomal distribution and degree of homologous and homeologous association in somatic and premeiotic cells, as well as the pattern of meiotic pairing.