First detection of endopolyploidy in tapetal cells and chromosomal anomalies in meiocytes of Viola pilosa cytotypes (2n=20) from Pir Panjal (Himalayas)
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Date
2023-01
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The Indian Academy of Sciences
Abstract
The nine Viola pilosa Blume populations studied from Pir Panjal contained 20 chromosomes. This count is not reported so far in Indian populations. Currently, comparison of tapetal and meiotic cells revealed the existence of synchrony in different developmental phases. Young tapetal cells at prometaphase co-occurred with the pollen mother cells (PMCs) at diakinesis to metaphase, mature tapetal cells with disintegrated chromatin material co-occurred with tetrads and no tapetal cells were found at mature pollen stage. Cytological studies in young tapetal cells revealed most of these to be endopolyploid, with each having 40 chromosomes. While outnumbering somatic cells contained clear 40 chromosomes which seemed to be the outcome of endomitosis, a sizeable number of cells possessed 40 sticky chromosomes at metaphase. Later chromosomes are likely to form restitution nucleus. Mature tapetal cells, occurring singly/cytomictically connected (3.2–26.31%) or showing coalescence (10.5–22.8%), did not contain recognizable chromosomes. Instead, they were charac- terized by disintegrated nuclear content. Further, meiotic studies revealed that the present population contained all/outnumbering euploid cells (2n=20); many of which exhibited nearly regular behaviour. However, 6.5–26.9% meiocytes of eight populations and 47% cells of P-Khe population depicted aneuploidy/contained quadri-octavalents, with per cent pollen viabilities of these ranging from 38.6 to 49.9. Going by the normal tapetal development in V. pilosa, existence of various chromosomal anomalies seems to have accounted for the reduction in gametic fertility of this taxon.
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Keywords
endomitosis, disintegrated chromatin, aneuploidy, pollen viability, Viola pilosa.
Citation
IQBAL TASIR, SHARMA GEETA . First detection of endopolyploidy in tapetal cells and chromosomal anomalies in meiocytes of Viola pilosa cytotypes (2n=20) from Pir Panjal (Himalayas). Journal of Genetics . 2023 Jan; 102: 1-6