Intrapopulation karyotypic variability inAllium royleiStearn - a threatened species

Abstract

Plants that are heterozygous for complex translocation from a small threatened population of Allium roylei Stearn from the Bani region of Jammu province (India) were analysed for karyotypic details. Somatic complements of all the plants analysed revealed heteromorphicity in one to three pairs of chromosomes. In addition, inter-individual differences were observed regarding the presence or absence of one of the two nucleolar chromosomes, the positions that different heteromorphic chromosomal pairs occupy in the karyoidiograms and the extent of differences in various chromosomal pairs. The present paper records for the first time structural chromosomal polymorhism in A. roylei and highlights the probable mechanisms underlying the origin and establishment of this polymorphism. The extensive karyotypic variability seems to have originated through repeated interchanges involving a number of non-homologous chromosomes. These anamolies are tolerated because there is no loss or gain of genes and, in addition, vegetative propagation is an efficient means of perpetuating the species.

Microsatellite marker based analysis of genetic diversity in short day tropical Indian onion and cross amplification in related Allium spp.

“…roylei is becoming very rare because of threats posed due to intrinsic and extrinsic pressures (Sharma and Gohil 2008) and is enlisted in the IUCN Red data list as an endangered species (Walter and Gillet 1997). Hence a comprehensive approach towards it conservation, maintenance and characterization is required.…”

Occurrence of differential meiotic associations and additional chromosomes in the embryo-sac mother cells of Allium roylei Stearn

“…Nevertheless, strong propensity of chromosomes to undergo interchanges as revealed by the presence of marked intrapopulation karyotypic variability in the present strain (Sharma and Gohil 2008) can be a potent mechanism for the production of propagules with new genotypes. While some of these may be of reduced vigour, formation of more vigorous ones is also expected during the course of evolution.…”

“…Although reports of occurrence of complex associations in male track (Sharma and Gohil 2003) and karyotypic heteromorphicity (Sharma and Gohil 2008) in this highly heterogenous population are on record, nothing was known about chromosome behaviour in its female track. The present communication fills this lacuna.…”

Cytological status of Allium hookeri Thwaites (2n = 22)

“…Chromosome sizes and index numbers of all the chromosomes were taken as mean with standard error of the values of the five cells studied. Following Sharma and Gohil (2008), chromosomes with index number = 0.67-1, 0.66-0.33 and \0.33 have been classified as median, submedian and subterminal, respectively.…”