Chromosomal behaviour and evolutionary trends in Chlorophytum (Liliaceae)

Abstract

Chlorophytum laxum R. Rr. (Liliaceae) is a common perennial herb occurring in many parts of India, Ceylon, Borneo, Tropical Africa and Australia. The earlier cytological studies report two numbers of chromosomes, viz. 2n = 14 & 16, for the species. The present study, based on meiotic behaviour, concludes that this species is a segmental allopolyploid from two closely related but still unknown species with 2n = 8 chromosomes. Further evolution proceeded in two different directions. In one, diploidization by chromosomal rearrangements resulted into species with 2n = 16 chromosomes, while in the other, elimination of a non‐homologous segment gave rise to species with 2n = 14 chromosomes and several autopolyploids.

Inter-specific variations in chiasma frequencies and terminalization in Chlorophytum Ker-Gawl.

“…Comparative analysis of chiasma frequencies in five species of Chlorophytum suggests the bivalent number in these species to vary from 8 to 14 to 21 due to polyploidy present in the genus, thus confirming the earlier reports for these species (Kumar and Rao 1958, Datta and Mitra 1968, Naik 1976. Presence of univalents in species like orchidastrum and glaucum in dicates the differential degree of condensation as also free terminalization ultimately leading to separation as univalents.…”

Karyomorphological studies in Chlorophytum Ker-Gawl.

“…In C. tuberosum and C. attenuatum one of the longest chromosomes (sequence number II) is the SAT chromosome and the SAT-knob is attached to the longth arm in attenu atum, whereas in C. laxum shortest chromosome (sequence number VIII) carries the satellite at tached to the short arm. These observations agree with those reported by Naik (1976). Like wise in comosum and orchidastrum the sequence number of the SAT chromosome is XII.…”

Chromosomal Behaviour and Seed Production in Chlorophytum comosum (Liliaceae).

“…Many species of this genus have been studied from cytotaxonomic and cytogeographic points of view (Baldwin and Speese 1951, Mukherjee 1957, Naik 1976, 1977. The basic chromosome number for the genus has been suggested to be x=8 and 7 , possibly derived as a secondary number from x=4 (Patil et al 1987) .…”