Karyotype analysis of ten draught resistant cultivars of Indian taro - Colocasia esculenta cv. antiquorom Schott

Abstract

Somatic chromosome number, detailed karyotype and genome size analysis were made to assess genetic diversity in ten drought resistant cultivars of Indian Taro (Colocasia esculenta var antiquorom Schott.). Karyotype analysis revealed genotype specific chromosomal characteristics and structural alterations in chromosomes of the genome, with variations of ploidy from 2n = 2 × = 28 (cv. Mothan, cv. Muktakeshi, cv. Sree Kiran, cv. Sree Pallavi, cv. Sunajhili) to 3n = 3 × = 42 (cv. Banky, cv. DP-25, cv. Duradin, cv. H-3, cv. Telia). Highly significant variations in the genomic length, volume and total form (TF) % were noted at variety level. Total genomic chromosome length varied from 46.96 μm in cv. Sree Kiran to 100.49 μm in cv. Duradin. Total genomic chromosome volume varied from 18.22 μm3 in cv. Sunajhili to 38.22 μm3 in cv. Duradin. Total form percentage was varied from 24.94 % in cv. Sree Kiran to 39.04 % in cv. H-3 confirming mostly of near metacentric to metacentric chromosomes in the karyotype. Significant variations in the 4C DNA content noted among the cultivars that ranged from 7.24 pg in cv. Sree Kiran to 18.24 pg in cv. Duradin; accordingly, genome size varied from ~7,095 to 17,875 Mbp. High genome size in all the triplod varieties with 3 x = 42 chromosomes could be due to the presence of extra set of chromosomes in the genome or high amount of repetitive DNA. The variation in the genome size at the cultivar level may be attributed to loss or addition of highly repetitive sequences in the genome. Detailed chromosomal analysis of ten drought resistant cultivars could help breeders to choose the diverse parents for breeding programme along with high yielding drought susceptible varieties for future crop improvement programme.