Chromosome count, meiotic abnormalities, pollen fertility and karyotype of Elymus semicostatus (Nees ex Steud.) Meld. (Family: Poaceae) from North-west Himalaya

摘要

The present study includes chromosome count, meiotic abnormalities, pollen fertility and karyotype of Elymus semicostatus from north-west Himalaya, India. This is the first attempt to present karyotype morphometric data of the species from India [2n = 4x = 28 = 22m(2sat) + 6sm]. At present 28 wild accessions of the species have been analysed, all of which shared the same tetraploid (4x) chromosome count of 2n = 28. In addition, seven accessions also showed the presence of 0-2 B-chromosomes in the meiocytes. Meiotic abnormalities were frequent and 17 accessions showed the phenomenon of cytomixis, involving chromatin transfer among meiocytes and associated meiotic irregularities in spindle activity and chromosomal segregation. Consequent to such meiotic abnormalities, these accessions showed pollen malformation in the form of sterile and variable sized pollen grains. Cytomixis in the species seems to be a natural phenomenon under the control of genetic factors and is responsible for inducing meiotic disturbance and pollen malformation.