Karyotype analysis in <i>Machaerium lunatum</i> (Linn. f.) Ducke

Abstract

ABSTRACT:The paper gives an account of the results of karyological investigation on Machaerium lunatum (Linn. f.) Ducke using root squash technique. Root tips (approximately 1 cm) were excised and pretreated in 0.002M 8-hydroxyquinoline for 3-3.5 hrs, fixed in 3:1 ethanol-acetic acid for 24 hrs, hydrolised with 5% HCl and squashed in drops of FLP orcein on clean glass slides. Mitotic chromosome slides were observed under research microscope and photomicrographs of 10 good quality metaphase plates were taken and recorded. A chromosome number of 2n = 30 was recorded for the taxon and the chromosomes varied from 0.83 -2.71 µm in length with karyotype of 7m+4sm+4st. The length of the long and short arms ranged from 0.64 -1.66 µm and 0.19 -1.05 µm respectively. The chromosomes varied from metacentric to subtelometacentric. This is the first report of the karyotype and chromosome of this species from Nigeria. In some other members of Fabaceae family the chromosome number, length and size including karyotypes have been described (Tabur et al. 2009; Adesoye and Nnadi 2011) but this information is lacking in the genus Machaerium. Also, the chromosome number of the West African species of M. lunatum is not yet determined. Therefore this work presents the first report on the chromosome number and karyotype of M. lunatum from Nigeria, West Africa. MATERIALS AND METHODSThe materials used for this work were sourced from brackish and fresh river bodies south-south Nigeria where M. lunatum grow namely Ogoni and