KARYOTYPE ANALYSIS OF PACHIRA (PACHIRA AQUATICA)

Abstract

Pachira aquatica belongs to the Bombacaceae group, the clades in the family Malvaceae. The subfamily contains about 304 species, most with high economic and medicinal values. Considering their importance, some of the plants attained special cultural status. Pachira comes from Central America and South America, introduced and spread to Europe, Africa, and Asia. The diversity of plant morphology can result from environmental factors interacting with genetic features, then expressed as phenotypes. Geographic isolation can prevent gene flow between populations. Geographic separation allows mutations to occur, and natural selection and genetic drift can alter allele frequencies differently in separate populations leading to allopatric speciation. The present study aims to determine the characteristics and chromosomal composition of P. aquatica. This study used the squashing method, often employed to obtain chromosomes by squeezing the preparations. The results showed that the number of chromosomes of pachira was 2n = 66. The chromosome length of pachira ranged from 0.812±0.009 to 1.955±0.009 μm. The chromosome shape of pachira is metacentric. The karyotype arrangement of pachira is 2n = 2× = 29m + 4sm, where 2n equals to 29 pairs of metacentric chromosomes and four pairs of submetacentric chromosomes. The intrachromosomal asymmetry index (A1) of the chromosome of pachira scored at 0.19±0.001, with the value of the interchromosomal asymmetry index (A2) at 0.224±0.021.