Karyotype Analysis from Aerial Roots of Piper nigrum Based on Giemsa and Fluorochrome Banding

Abstract

Piper nigrum is an important age-old herbal plant of the family Piperaceae. Chromosomal analysis a part of genomic research to conserve plant genetic resources has confronted difficulties in this particular species with conventional methods primarily due to its very small chromosome size and rich cytoplasmic contents. Different chromosome number from 2n=52 to 128 have been reported in this species. A reassessment of chromosome analysis not attempted earlier with aerial roots and enzymatic maceration and air drying (EMA) method has been standardized in this species. Well scattered cytoplasm free metaphase plates stained with Giemsa revealed 2n=52 very small chromosomes. Total chromosome length attains to 75.36±011 µm. Most chromosome pairs except one ranged from 0.99 to 1.81 µm. Karyotype formula is determined as 6M+26m+20sm and accordingly, idiogram is constructed. Fluorochrome banding with two contrasting nucleic acid dye DAPI and CMA provided positive signals for both of the stains on the very small chromosomes. The standardized EMA method and fluorochrome banding is repeatable and will help to evaluate other important species and genus within this family for the conservation of plant genetic resources.