Cytomixis Induced Meiotic Irregularities and Pollen Malformation in Clematis graveolens Lindley from the Cold Deserts of Kinnaur District of Himachal Pradesh (India)

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Present cytological investigations recorded the first ever diploid chromosome (n=8) count in 9 accessions under 3 morphovariants (MV) of Clematis graveolens. Out of 9 accessions, individuals of MV-II and 3 individuals of MV-III depicted the phenomenon of cytomixis involving chromatin transfer among proximate pollen mother cells (PMCs) during male meiosis which occurred through narrow and broad cytoplasmic channels from early prophase-I to telophase-II. The migration of chromatin material has been observed to be partial as well as complete which resulted into the formation of hypo-, hyperploid and enucleated PMCs. Cytomixis induced various meiotic irregularities into PMCs such as pycnotic chromatin, interbivalent connections, chromatin stickiness, syncyte PMCs, laggards/micronuclei and chromatin bridges, out of plate bivalents, late disjunction of bivalents and PMCs with multiple poles. These meiotic abnormalities resulted into abnormal sporad formation and 1.68–10.00% pollen sterility Furthermore, the range in size of pollen grains in the species is affected considerably due to cytomixis and the process of pollen fusion where 2–3 pollen grains were fused resulting into very large sized pollen grains. The large sized pollen grains in some accessions were also resulted as the products of syncyte PMCs.
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