Synaptic mutants represent http://www.selleckchem.com/products/ganetespib-sta-9090.html one such event in the cell cycle where homologous chromosomes either lack pairing during late prophase I [30] or they are not able to generate or retain chiasmata [26, 31, 32]. To describe the condition where homologous chromosomes failed to pair, the term asynapsis is employed. On the other hand, in cases where chromosomes paired at zygotene and pachytene but failed to remain paired during subsequent stages of meiosis refers to desynapsis. In the present investigation all the analysed PMCs did not reveal the expected chromosome associations of 14II, instead they exhibited completely random dispersion of univalents in the cytoplasm at M-I suggesting asynaptic mutation. Peirson et al.

[33] were of the opinion that in most of the asynaptic mutants univalents show random distribution in the cytoplasm at M-I and never align at the equatorial plate while in desynapsis bivalents and univalents orient at the equatorial plate during M-I. Synaptic variation resulting in complete and partial failure of chromosome pairing of homo/homeologous chromosomes has been studied in a large number of species [15, 26, 34�C38]. Physical and chemical mutagens are widely reported to induce synaptic mutations [39�C41] but only a few reports are available on the spontaneous origin of synaptic variants in natural populations [36�C38, 42, 43]. A large number of factors such as drastic temperature fluctuation, ageing, water content and humidity, soil conditions, and gene mutations [26, 43�C45] are reported to be responsible for the spontaneous origin of synaptic mutants in natural populations.

The accession with completely normal meiotic behaviour and 100 percent pollen fertility was growing along with the individual which showed synaptic mutation. So the genetic factors seem plausible behind the synaptic irregularities in the species. Another interesting phenomenon in the presently investigated species is the formation of restitution nuclei. Restitution nuclei were formed because univalent chromosomes/daughter chromatids failed to distribute themselves uniformly at the poles during anaphases. These restitution nuclei resulted into the formation of dyads and triads which subsequently produced two types of pollen grains. Different methods had been used to detect production of 2n pollen grains in plants. Owing to the relatively close correlation between larger pollen grains and 2n status, the presence of large-sized pollen grains had been frequently used as a criteria for the indication of 2n pollen [23, 46�C52]. Presently, on the basis of size, two types of pollen Entinostat grains were categorized as n (normal reduced) and 2n (unreduced). The pollen grains which were 1.5-times larger than the normal pollen were regarded here as 2n pollen grains.