Cytogenetic Rationale for Probable Amphidiploid Origin ofDipcadi erythraeumWebb. & Berth. - A Rare and Endemic Plant of Indian Thar Desert

Abstract

-Five accessions of Dipcadi erythraeum, a rare and endemic, bulbous medicinal plant of Thar desert in India, were collected from different districts of Rajasthan (India) to study the intra-specifi c genetic variation existing in their natural populations. To resolve species specifi c cytogenetical mechanism leading to evolution of D . erythraeum, mitotic and meiotic analyses were carried out. The karyotypes of various accessions of D. erythraeum were precisely resolved into ten distinct homologous pairs, not into groups of chromosomes. A striking feature observed meiotically is that bivalents are the most frequent association, while multivalent associations were completely absent in any of the PMCs presently analyzed. Almost diploid like behavior of chromosomes has been the hallmark of the PMCs investigated presently. Overall cytogenetical mechanism underlying the speciation and evolution indicates the probable amphidiploid origin of D. erythraeum.

Comparative Cytogenetics and Fluorescent Chromosome Banding in Five Indian Species of Dipcadi Medik

“…In this study, we reconfirm 2n = 20 for D. montanum. Jakhi et al [31] first reported 2n = 22 and n = 11 in D. erythraeum collected from Rajasthan, reconfirmed by Jehan et al [12], although 2n = 20 has also been reported in the species [30]. We confirm 2n = 22 in D. erythraeum in two populations from Rajasthan.…”

“…Somatic chromosome counts available globally for about 14 species of Dipcadi [25] have revealed wide diversity in chromosome number (2n = 6, 8, 16, 20, 22, 24, 32, 40). Since D. serotinum, with a broad distribution (Europe and Northern Africa to the Arabian Peninsula and India) shows 2n = 2x = 8 chromosomes with n = 4 [33], a base chromosome number [49,52] of x = 4 has been suggested [30]. Thus, considering x = 4, taxa with 2n = 12, 20, 22 in the present study may be polyploid derivatives.…”

“…Among the species occurring in India, D. concanense, D. goaense and D. saxorum show 2n = 12 chromosomes while D. montanum and D. ursulae show 2n = 20 chromosomes [14,[27][28][29]. Dipcadi erythraeum is reported to have 2n = 20 [30] as well as 2n = 22 chromosomes [31]. Meiosis shows regular bivalent formation in most of the species studied [14,[30][31][32].…”

“…Dipcadi erythraeum is reported to have 2n = 20 [30] as well as 2n = 22 chromosomes [31]. Meiosis shows regular bivalent formation in most of the species studied [14,[30][31][32]. Karyotype analysis in the Indian species of Dipcadi exhibits asymmetric bimodal karyotypes but detailed characterization is lacking [14,[30][31][32][33].…”

Meiotic Studies in <i>Withania somnifera</i> (L.) Dunal.: A Threatened Medicinal Herb of Indian Thar Desert

“…Such information through association analysis of bivalents were reported in an important medicinally important desert plant i.e. Dipcadi erythraeum recently, which is also an amphidiploids ori-gin as revealed by cytogenetical investigation recently [18]. However, in the absence of karyological data it is difficult to confirm the apparent amphidiploids origin of the species.…”