Karyotype Analysis of Ten Species of <i>Ipomoea</i> Jacq.

Abstract

SummaryThe genus Ipomoea with about 500 species is distributed in the tropical and subtropical regions of the world. The species are not only among the most beautiful ornamental plants, they are also important because of their medicinal value. The present study deals with the karyotype analysis of 10 species of Ipomoea growing in Maharashtra state of India. All the species analysed are diploid, showing 2n=30. I. aquatica has the smallest chromosomes, 1.25 to 2.67 μm, with a mean length of 1.99( 0.38), and the total length of the haploid component as 29.88 μm, while I. carnea has the longest chromosomes, at 2.13 to 4.79 μm, with mean length as 3.39( 0.74) and total length of the haploid component at 50.83 μm. The karyomorphological investigations revealed that none of the species had a symmetrical karyotype. The degree of asymmetry was, however, low. Amongst the several parameters studied, that of Stebbins (1971) and the AI values were found to be the most reliable for assessing asymmetry. The species falling under group 2B of Stebbins had higher AI values as compared to those of group 1B, proving that they are more evolved. The heterogeneity within the 10 species could be traced by AI values.

Phylogenetic study of Ipomoeeae (Convolvulaceae) based on chromosome painting

“…chromosomes and three species (I. hederifolia, I. coccinea and I. pes-tigridis) had 28 chromosomes, which was in conformity to previous reports for the same species[35][36][37][38][39]. However, three species with 28 chromosomes were divided into different smaller clades within Astripomoeinae and Argyreiinae together other 2n = 30 species by Eserman et al[10].…”

“…Having same chromosome number between species is often indicative of a close evolutionary relationship [35]. Previous cytological analysis revealed that the species in genus Ipomoea contained the diverse chromosome numbers of 2n = 28, 30, 32, 60 and 90, and the majority of the species had chromosome number of 2n = 30 [36][37][38][39]. Among our analyzed 31 species, Although CCP provides good phylogenetic resolution at the clade level in Ipomoeeae tribe, it is difficult to distinguish species and estimate the species relationship at each clade with same CP pattern.…”

“…Previous cytological analysis revealed that the species in genus Ipomoea contained the diverse chromosome numbers of 2n = 28, 30, 32, 60 and 90, and the majority of the species had chromosome number of 2n = 30[36][37][38][39]. Among our analyzed 31 species, 28 species had 30 chromosomes and three species (I. hederifolia, I. coccinea and I. pes-tigridis) had 28 chromosomes, which was in conformity to previous reports for the same species[35][36][37][38][39]. However, three species with 28 chromosomes were divided into different smaller clades within Astripomoeinae and Argyreiinae together other 2n = 30 species by Eserman et al[10].…”

Cytogenetical studies of some Convolvulaceae members from the Western Ghats, India reveal uniformity in karyotypes

“…These chromosome numbers not confirming to base numbers x = 14 and x = 15 can be attributed to polyploidy, aneuploidy or dysploidy or to the occurrence of polysomaty (Vij et al 1977;Sampathkumar 1979;Lekhak et al 2018). Sampathkumar (1979) studied the karyomorphology of eighteen Ipomoea species whereas Rane et al (2012) studied ten species. In both the studies chromosomes with median and submedian centromeres were observed.…”

“…On account of its tremendous utility in medicinal and ornamental fields, the family is cytogenetically well explored. In India, somatic chromosomes of these members have been the focal point for the majority of studies (Vij et al 1974(Vij et al , 1977Bir and Sidhu 1975;Bir et al 1978;Roy 1979;Sampathkumar 1979;Rao and Mwasumbi 1981;Sinha and Sharma 1992;Rane et al 2012;Lekhak et al 2018;Lawand et al 2019;Ramanpreet and Gupta 2018). Most of these studies recorded chromosome counts for species of Ipomoea, Argyreia Lour., Merremia and Operculina Silva Manso.…”