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Electronmicroscopic study has revealed a dicentric chromosome in the root tip cells of diploid Aloe vera, hitherto unreported in somatic cells of plants. The morphological aspects are described and the implications of such structural features of the dicentric are addressed in a functional perspective. It is also proposed that the presence of two functional kinetochores need not invariably lead to chromosome instability and loss.

The permanent translocation heterozygote, Rhoeo spathacea shows a characteristic ring of all chromosomes at metaphase-I of male meiosis. Elimination of bivalent formation completely due to extreme heterozygosity poses a special problem for reductional division at meiosis-I where the maternal and the paternal sets need to be separated to different poles. Unlike bivalent meiosis, the functions of SC formation, pairing and recombination required for reductional segregation have to be fulfilled by only telomeres which are the only areas of contact among the chromosomes in the ring. The participation of telomeres in these events assumes significance in view of the balanced lethal gene system imposed by translocation heterozygosity, and the particular requirement that only alternate chromosomes segregated to the same pole results in fertile pollen. This paper throws some light on the telomere functions in R. spathacea in the light of our present understanding of telomere biology. The prospects of using R. spathacea as a model organism to dissect molecular aspects of several telomere related functions are also discussed.

Karyotypes of six species of Barleria L. occurring in South India viz., B. acuminata, B. buxifolia, B. gibsoni, B. involucrata var. elata, B. noctiflora and B. strigosa are studied. All the six species have the same chromosome number of 2n=40. However, each species is distinct in respect of relative positions of centromere, presence/absence and position of satellites and total haploid chromatin length. The diagnostic value of the karyomorphological details in these taxa is discussed.