Genotyping Sorghum Germplasm In Tanzania Using Microsatellite Markers

ABS TRACT

Microsatellite markers are increasingly being used in crop plants to discriminate

among genotypes and as tools in marker-assisted selection. In this study microsatellite

markers were used to quantify the genetic diversity within as well as among 200

accessions sampled from sorghum germplasm collection at Tanzania National gene

bank germplasm collection of sorghum. Although all methods did not provide similar

description of relationships between accessions, there existed some consistency in

discriminating accessions which are closely related and the ones which were distantly

related. But, considerable variation was found at the 39 microsatellite markers

analysed, with an average number of alleles per locus equal to 9.49 within accessions,

the lowest was 2.0 from Xtxp114, Xcup61 and the highest number of allele was 25 as

for Xgap206 marker. The collection of sorghum appeared moderately structured

genetically with about 59% of the average gene diversity occurring among accessions.

The SSR markers were moderately polymorphic, with diversity

indices ranging from 0.07 to 0.91 with mean of 0.55.The UPGMA

dendrogram based on SSR marker data clearly discriminated among

clusters, even though some consistency in classification was

observed among clusters. However, differentiation among morphologically

accessions of sorghum, or among geographic origins, accounted for less than 35% of

the total genetic diversity. Data in this study demonstrated that accessions of Tanzania

sorghum contain a great deal of genetic diversity as indicated by the observed number

of alleles. These results are in global agreement with those obtained previously with

allozyme markers. It was also possible to show that microsatellite data are useful in

identifying individual accessions with a high relative contribution to the overall allelic

diversity of the collection. Therefore, from the result outcome the inventory was

compiled that will be used in future to characterize the rest of the sorghum germplasm

and make use of the identified potential parental genotypes for mapping populations

and marker assisted selection programs.