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Karyotypic studies in some members of Caesalpinia spp.Linn.

Om Prakasha & Meenakshi Singha*
Plant Biosystematics and Molecular Biology Lab.
Dept. of Botany, Patna Science College, P.U, Patna-5, Bihar, India.

Received 22nd December, 2011; Revised 15th February, 2012

Abstract : Somatic chromosomes of four taxa of Caesalpinia Linn. (family Caesalpiniaceae, tribe Caesalpinieae : C. bonduc, C. coriaria, C. pulcherrima var. flava and C. pulcherrima var. pulcherrima) were studied. These species were diploid (2n = 24) and showed a variable percentage of tetraploid cells. Chromosomes were small in size : the average chromosome length was 1.89µm. The haploid karyotype length was relatively homogeneous  (range 20.78-25.12µm, mean : 22.71). Although Caesalpinia species were morphologically different, their differentiation was not followed by chromosomal variatioins. All the taxa showed same chromosome number and asymmetrical haploid karyotypic formula. Satellites were present in chromosome pair no. 4 and were attached to the short arms in a single species of C. pulcherrima in both taxa. A cluster analysis based on karyotypic features showed that C. bonduc and both taxa of C. pulcherrima were close and that C. coriaria was distinct because it had the shortest total chromatin length and highest total form percentage. Karyotypic features obtained suggest that no major visible chromosomal rearrangement have occurred during the differentiation in the group, although cryptic structural changes, duplication or deletion of segments of similar length, may have taken place.

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