Chromosome counts through male meiosis in some dicots from the hills around Shimla, Himachal Pradesh

Abstract

In the present work, detailed male meiotic studies were performed on 24 dicot species from the hills around Shimla within the altitudinal range of 1880-3140 m and which include the first ever chromosome count for Polygonum polystachyum (n=11) from India. Further, a new intraspecific aneuploid cytotype of 2n=18 for Impatiens brachycentra and B-chromosomes have been reported in Pimpinella acuminata. The phenomenon of cytomixis involving chromatin transfer among neighbouring PMCs along with associated meiotic irregularities and pollen malformation has been detected in some individuals of Clematis grata (n=8) and Ranunculus laetus (n=14). For the rest of the species, the study confirms the earlier chromosome counts by other workers. Analysis of chromosomal data on the worked out species reveals that aneuploidy and polyploidy has a role to play in evolution.