Karyology of eight bamboo species endemic to Southern India

Abstract

Species belonging to the genus Ochlandra Thwaites, the reed bamboos, play a significant role in sustaining the ecology of forests and the livelihood of rural communities in the Western Ghats. Karyology of this predominantly endemic genus of the region is poorly understood. Of the ten species belonging to the genus, chromosomal information is known for only two species. We studied mitotic and/or meiotic chromosomes of eight species, using squash and smear techniques. We report chromosome number (2n) of six species for the first time and two additional 2n reports of a previously studied species, O. travancorica (Bedd.) Gamble. The species and their chromosome numbers are: O. keralensis M. Kumar, Remesh & Sequiera and O. spirostylis M. Kumar, K. K. Seethal. & Sequiera (2n = 48), O. ebracteata Raizada & Chatterji (2n = 64), O. beddomei Gamble and O. setigera Gamble (n = 36, 2n = 72), O. scriptoria (Dennst.) C. E. C. Fisch. (2n = 72), O. wightii (Munro) C. E. C. Fisch. (n = 36, 2n = 60, 72) and O. travancorica (n = 24, 2n = 48, 72, 96). The basic chromosome number of the genus is x = 12. The somatic chromosomes of all studied Ochlandra species are small in size, with a length ranging from 0.45 to 2.50 µm. The present study has provided new perceptions on speciation, evolution and taxonomy of the genus and indicates that the taxonomic muddle in O. travancorica is due to intraspecific genetic variability as evident by chromosomal numerical variation and polyploidy.