Short Arm Telocentric B Chromosome in Pennisetum typhoides (Gramineae)

Abstract

A derived B chromosome which is telocentric and entirely heterochromatic was obtained upto irradiation of dry seed of Pennisetum typhoides diploid stock. Un-like the other B's reported earlier in this species, this short B is numerically stable. Only one B is present in a plant, it is constant in root tip cells and pollen mother cells. In plants with this derivative B the mean A chromosome chiasma frequency was observed to be lower when compared to sib plants without the B; also the pro-portion of non-distal chiasmata has increased in PMC's with the B. The transmis-sion frequency was low as the B was recovered in 8 to 10 percent of the progeny.