Karyomorphology of three species of Aristolochia – rare and endemic medicinal plants of Assam, India

Abstract

Karyomorphological analyses were conducted of three species of Aristolochia from Assam, India: Aristolochia indica Linn., Aristolochia saccata Wall., and Aristolochia cathcartii Hook. f. The study included determination of somatic chromosome number, total chromosome length, volume, arm ratio and centromeric position. Chromosome classification was done on the basis of the position of the centromere. Their karyotypes were as follows: 2n = 12 for Aristolochia indica Linn. and Aristolochia saccata Wall., and 2n = 20 for Aristolochia cathcartii Hook. f. A. indica consists of six median chromosomes and six metacentric chromosomes. The chromosome length varied from 1.36 μm to 3.06 μm while their volumes ranged from 0.004 μm3 to 0.176 μm3. The relative length of the chromosomes varied from 5.71 μm to 12.85 μm. A. saccata possesses six median, two metacentric and two submetacentric chromosomes. One pair of metacentric chromosome possesses secondary constriction at subterminal region. The chromosome length varied from 1.36 μm to 2.38 μm while their volumes ranged from 0.0046 μm3 to 0.137 μm3. The relative length of the chromosomes varied from 6.25 μm to 10.93 μm. In A. cathcartii, the 20 somatic chromosomes comprised of eight median chromosomes, eight metacentric chromosomes and four submetacentric chromosomes. The chromosome length varied from 1.36 μm to 4.08 μm while their volumes ranged from 0.004 μm3 to 0.235 μm3. The relative length of the chromosomes varied from 2.32 μm to 6.98 μm. The chromosomes of A. indica Linn., i.e. only median and metacentric chromosomes, suggest a more primitive nature.