Cytological studies of sporophytic and gametophytic generation of two bulbaceous species Ledebouria revoluta and Drimiopsis botryoides (Asparagaceae)
2016
Haque, Sk Moquammel | Ghosh, Biswajit
Detailed cytological characteristics of both sporophytic as well as gametophytic generation of two bulbaceous species, Ledebouria revoluta and Drimiopsis botryoides , were studied by investigating together pollen mitosis and root tip mitosis along with meiosis. A comparative study showed there was no significant difference between chromosome characteristics of haploid and diploid plants. The chromosome number of L. revoluta was 2 n = 30 (in root tip) and n = 15 (in pollen) and that of D. botryoides was 2 n = 66 (in root tip) and n = 33 (in pollen). Both genera have a monomodal chromosome with gradual decreases in size from the longest, 6.79 μm, to the shortest, 1.50 μm, in L. revoluta , and 9.65 to 1.55 μm in D. botryoides . The karyotypic formula of L. revoluta was 20m + 10sm and D. botryoides was 30m + 14sm + 16 st + 6t. All the meiotic events were found to be normal in both genera and a clear 15 and 33 bivalents were observed in L. revoluta and D. botryoides accordingly. Very few meiotic abnormalities were observed in L. revoluta (about 2.4%); a comparatively higher percentage (nearly 7.9%) of abnormalities were observed in D. botryoides in the form of laggard, bridge, chromosome stickiness, early or late anaphasic movement, etc. However, the ultimate product of meiosis, i.e. microspores/pollens, are normal with an expected haploid chromosome number (n = 15 and 33 accordingly). Overall, L. revoluta is karyotypically less asymmetrical with a lower chromosome number than D. botryoides , indicating that D. botryoides is evolutionarily more advanced than L. revoluta .
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