Characterization of Four Specimens of Allium sativum L. by Differential Karyotype and RAPD Analysis

Abstract

Four specimens of Garlic (Allium sativum L.), viz., Local monocloved, Local multicloved, Indian multicloved and a wild specimen (a tribal specimen locally called Joldong), were compared karyotypically by differential staining with orcein, CMA and DAPI. In addition, DNA fingerprinting was carried out by using RAPD. The wild specimen was found to possess 2n=32 chromosomes while the other three specimens had 2n=16 chromosomes with more or less similar total length of 2n chromosome complement. The four specimens showed distinct centromeric formulae, i.e. 12m+4sm in Local monocloved, 8m+8sm in Local multicloved, 10m+6sm in Indian multicloved and 26m+6sm in the wild specimen. In Local monocloved, a unique structure in a pair of sub-metacentric chromosomes revealed the occurrence of homozygous paracentric inversion. The four specimens of Allium sativum L. have distinct CMA- and DAPI-banding patterns. Asymmetric banding patterns in homologue members indicated minute chromosomal alterations. The two entirely DAPI fluoresced chromosomes were found in only the Local monocloved specimen. These chromosomes were unique and thus could be used as marker chromosomes for this specimen. Each specimen showed characteristic RAPD fingerprinting. The unique RAPD fragments could be used as markers for the respective specimens. Differential karyotype analysis did not support to consider the multicloved specimens as autotetraploid of the monocloved, inspite of having gigas features. The wild specimen showed a completely different karyotype than the other three specimens. It was placed alone in a separate cluster on the basis of RAPD analysis with highest genetic distance. Therefore, a thorough investigation is necessary to elucidate the taxonomic status of this wild specimen.