Comparative Karyotype Analysis of Delphinium malabaricum var. malabaricum (Huth) Munz. and Delphinium malabaricum var. ghaticum Billore.

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Delphinium malabaricum (Huth) Munz. and its variety D. malabaricum var. ghaticum Billore (Ranunculaceae) were cytologically examined. Both taxa were found to possess 2n=16 diploid chromosome number. The 8 pairs of homologous chromosomes were characterized into 1 metacentric, 1 submetacentric and 6 subtelocentric chromosomes. The total length of diploid complements and range of chromosome length were more or less the same in the species and its variety. The length of metaphase chromosomes ranged from 1.42 to 5.35 μm in D. malabaricum var. malabaricum and from 1.77 to 5.30 μm in D. malabaricum var. ghaticum with an average length of 2.88 μm and 2.92 μm, respectively. The total chromosome length (TCL) of the former was 23.05 μm and that of the latter was 23.38 μm. The prevalence of chromosomes with subtelocentric centromeres indicated a tendency towards asymmetric karyotype, which revealed an advanced feature. Hence both the taxa belong to Stebbins's 2B type karyotypic symmetry class. The results revealed that D. malabaricum var. malabaricum and D. malabaricum var. ghaticum have a similar karyotype pattern, despite differing morphologically. Thus, it may be concluded that the external morphological variation occurred independently of the chromosomal variation, which may have played a prominent role in the intraspecific differentiation of D. malabaricum.
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