Cytological studies of sporophytic and gametophytic generation of two bulbaceous speciesLedebouria revolutaandDrimiopsis botryoides(Asparagaceae)

Abstract

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 2n = 30 (in root tip) and n = 15 (in pollen) and that of D. botryoides was 2n = 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.

Callus mediated shoot organogenesis and regeneration of cytologically stable plants of Ledebouria revoluta: An ethnomedicinal plant with promising antimicrobial potency

“…All the regenerated and parental plants of our experiments contained 2n = 30 chromosomes, which are corroborated with the previous cytological report of L. revoluta [36]. Variations in chromosome number and structure are the commonly observed chromosomal abnormalities in callus cells and the plants regenerated from them [10], [13].…”

A karyomorphological study in <i>Ledebouria crispa</i>, Asparagaceae

“…2n = 20, 22, 26, 30, 38, 40, 44, 45, 46, 58, 60, 64, 68 were reported as the chromosome number of of L. revoluta (Raghavan and Venkatasubban 1940a, b;Sheriff and Murthy 1946;Rao 1954;Ratter and Milne 1973;Sen 1973a, b;Sheriff 1979;Sarkar et al 1980;Valdes-Bermejo 1980;Sheriff and Rao 1981;Subramanian 1981;Chakraborti & Sen 1983;Mathew 1988, 1990;Dixit et al, 1989;Nair 1989;Chakravarty and Sen 1992;Stedje 1996;Johnson and Brandham 1997;Sheeba and Vijayavalli 1998;Haque and Ghosh 2015), this species has a large variation of the chromosome number. And n = 10, 11, 17 and 30 were reported on L. floribunda (Jessop 1972) which was reported n = 18 or 19 (Jessop 1970), this species also showed a large variation on the chromosome number.…”

Karyomorphological Study in <i>Ledebouria botryoides</i> (Asparagaceae)

“…Cytogenetically, it is a complex with various chromosome counts on record, viz. 2n=80 (Matsuura and Suto 1935); 2n= 68 (Mahalakshmi and Sheriff 1970); 2n= 66 (Sharma 1970);2n= 66, 68, 126 (Sen 1973); 2n= 60 (Vij et al 1982); 2n= 44, 55 (Stedje and Nordal 1987); 2n=30 (Vijayavalli and Mathew 1988); 2n= 44, 55, 66 (Stedje 1994) and 2n= 66 (Haque and Ghosh 2016). Chromosome number is the most frequently documented cytological character.…”

“…Chromosome number, size, symmetry, position of the centromere, secondary constriction, and heterochromatic regions are the mainly used diagnostic chromosomal landmarks used in comparative analysis (Vimala et al 2021). Expensive techniques including chromosome banding and fluorescence in situ hybridization (FISH) may be necessary to establish a relationship between taxa with uniform (symmetric) karyotypes; however, taxa with asymmetric karyotypes can be studied with simple squashing and conventional staining with orcein/carmine (Haque and Ghosh 2016). The structure and behavior of plant chromosomes during reduction division is important because the genetic variation of both gametes and the future sporophyte depends on it (Haque and Ghosh 2016).…”

“…Expensive techniques including chromosome banding and fluorescence in situ hybridization (FISH) may be necessary to establish a relationship between taxa with uniform (symmetric) karyotypes; however, taxa with asymmetric karyotypes can be studied with simple squashing and conventional staining with orcein/carmine (Haque and Ghosh 2016). The structure and behavior of plant chromosomes during reduction division is important because the genetic variation of both gametes and the future sporophyte depends on it (Haque and Ghosh 2016). Polyploidy is common among plant species, especially in monocots and this raises special issues for the analysis of meiosis in many plants (Haque and Ghosh 2016).…”