Intrapopulation karyotypic variability in<i>Allium roylei</i>Stearn - 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.