Comparative Chromosome Morphology and Karyotype Study in Two Varieties Of (Alliumcepal.) And Garlic (Allium Sativum)
In this present study, karyotypes of three varieties in the genus Allium were examined. The study aimed at investigating intergeneric and intrageneric relationships among the varieties studied. The three varieties studied were diploid with 2n = 2x = 16. Highest total chromosome length was in A. sativum (white variety) was 64-164 μm. The lowest in A. cepa (white variety) as ranges from 21-41 μm. The chromosome types were investigated as mostly metacentrics (M), submetacentrics (Sm) and few subtelocentrics (St). The length of the roots that were excised was between 1 and 1.5 cm. Pre-treatment of root tips was done with 0.05 % colchicine for 5 hours. The roots were fixed in Carnoy’s fluid, a 6:3:1 solution. Aceto-orcein (2 %) was used for the staining of the fixed root tips. The tips were then squashed in aceto-orcein. A photomicrograph was obtained using the MOTIC 2.0 camera. The chromosomes of the haploid were arranged and numbered according to their total length in descending order, and their ideogram was developed. Karyotype formula is 5M+9Sm+2St in A. cepa (red variety) and White variety was 4M+12Sm while A. sativum (white variety) was 4M+11Sm+1t. The karyotypes of the species were examined on the grounds of various karyotype asymmetry indices. Revealed that A. cepa (red variety) varieties are symmetrical while A. sativum (white variety) is moderately asymmetrical. Two of them, A. cepa (red and white variety) fell in the 1A while A. sativum (white variety) belonged to the 1B category of Stebbins’ classification.
Keywords: Karyotype, Morphology, Asymmetrical, Symmetrical, Allium cepa, Allium sativum, chromosomes.