GENETIC Diversity in some Introduced Cassava Genotypes via Simple Sequence Repeat Markers (SSR)

T.M.Salim1, H.S.Baiea1, M.M.M.Bekhit1, M.S.Abdel-Sabour1 and M.M.Elnagar2"


The objective of this study was to characterize morphologically and molecularly genetic diversity of three important cassava genotypes (Manihot esculenta Crantz). Three Introduced cassava genotypes were utilized as a part of the present study. These genotypes named American, Brazilian, and Indonesian. These plants procured name as per its unique area. Morphological appraisal showed a few contrasts between the three genotypes. Plant leaf hues demonstrated clear differences depending on genotype for instance leaves of Indonesian genotype was green, including leave neck, then again leaves of the American genotype was green shaded with green-red neck while the leaves of the Brazilian genotype was green with some reasonable red spots. The three genotypes likewise differentiated in branching capacity as the American genotype frame three branches while Indonesian and Brazilian genotypes have no branching capacity. The outer shade of the American tubers was light brown; then again outside tuber shade of Indonesian and Brazilian genotypes was dark brown. Concerning the interior shade of Brazilian genotype, tubers were pink, while the Indonesian tubers were light pink, yet American genotype was white. Tuber lengths likewise measured, and the American tubers were the tallest, then Brazilian tubers were taller than Indonesian which considered the briefest. Concerning tuber distance across, Brazilian tuber width gave the most elevated qualities, trailed by the American, while the Indonesian gave least values. American tubers weight was the biggest, followed by Brazilian, and Indonesian tubers weight was the least one. Ten SSR primers successfully generated reproducible and reliable amplicons for the three imported cassava genotypes. Population structure was analysed by means of genetic distances and probabilistic models; allelic frequencies were used in order to assess the genetic diversity indexes (Ht, Ho, PIC, % polymorphism and a number of alleles) for each studied locus. Some microsatellite loci typed were polymorphic. The average number of alleles per locus was 2.700 ranging from 1 in SSRY38 and SSRY103 to 4 in SSRY108 and SSRY4. Mean observed heterozygosity was 0.02 ranging from 0.000 in SSRY106, SSRY38, SSRY103, SSRY177, GA-136 and GA-134 to 0.667 in SSRY108 and SSRY4 while the mean expected heterozygosity was 0.600 ranging from 0.000 in ssry38 and ssry103 to 0.800 in SSRY108, SSRY177, SSRY4, GA-136 and GA-134. The average PIC was 0.443 ranging from 0.000 at locus SSRY38 and SSRY103 to 0.620 at locus SSRY108 and SSRY4. Outcomes demonstrated that genetic similarity between the three cassava genotypes was running from 25% to 41.7%, highest percentage 41.7 was between American and Brazilian genotypes. The lowest percentage of 25% was between American and Indonesian genotypes. Dendrogram exhibited a strong association between the American and Brazilian, on the other hand, this association was lower between the American and the Indonesian relationship, and these are because of the root of species sources.

Key words

Cassava, Manihot Esculenta Crantz, Morphological diversity, Molecularly genetic diversity, SSR.