Cytomixis and Associated Abnormalities during Male Meiosis in a New Tetraploid Cytotype of <i>Vicia pallida</i> Turcz. (Fabaceae)

Abstract

Cytological work on Vicia pallida Turcz. presents male meiotic studies in wild accessions gathered from the Kinnaur district of Himachal Pradesh. All 3 accessions uniformly shared the same meiotic chromosome number of n=12 in which 5 bivalents are relatively small sized as compared with the remaining 7 bivalents. This is the first report of tetraploid cytotype in the species against the earlier record of diploid cytotype (n=7) from the other region of Himalaya. Out of the 3 accessions scored presently, 1 accession showed a regular 12 bivalent formation, equal chromosome segregation during anaphases/telophases, normal tetrad formation and 99% pollen fertility with uniform sized pollen grains. The remaining 2 accessions depicted pollen mother cells (PMCs) with irregular meiotic behaviour which included the phenomenon of chromatin transfer among proximate meiocytes at different stages of meiosis, interbivalent connections and chromatin stickiness, out of plate bivalents at metaphase-I, lagging of chromosomes/laggards at anaphases, abnormal sporads (tetrads with micronuclei and polyads) and consequently some pollen sterility and pollen grains of variable sizes. The phenomenon of cytomixis which induces various meiotic abnormalities in the PMCs and consequently pollen sterility and pollen grains of heterogeneous sizes in V. pallida seems to be under direct genetic control.