Chromosome Numbers and Karyotype Studies of Few Members of Malvales

Chromosome numbers and karyomorphological data are essential in selecting the suitable species for plant breeding programmes, resolving taxonomic confusions, tracing the evolutionary tendencies and evolving ployploid varieties. In this study, we analysed the karyotype analysis of five malvales species, viz., Sida rhombifolia, Sida spinosa, Sida acuta, Sida glutinosa and Sida cordata. Somatic chromosome numbers, karyotypes, range of chromosome length, arm ratio and haploid chromatin length were studied for these species. The result of this study showed, Sida rhombifolia and Sida spinosa were found to be 2n=14, Sida acuta was 2n=28 and Sida glutinosa and Sida cordata were found to be 2n=32 somatic chromosome numbers. Somatic chromosome length ranges from 0.95 to 3.23 μm, arm ratio ranges from 0.22-0.91 μm where as haploid chromatin length ranges from 13.49 to 31.74 μm. Their karyotypes were commonly bi-modal, homogenous assemblage and decreasing in length from the longest to the shortest chromosomes. Experimental results have confirmed that the chromosome numbers in Sida are not just multiplies of a single basic number. Different basic number of x=7, 8, 9, 11 and 17 occur in the genus.

Author(s): K.H. Venkatesh, B. Dinesh, N. Venu and Munirajappa

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