Assessment of Kenyan sorghum diversity using morphological characters and molecular techniques

Abstract

Characterization of the available Kenyan sorghum genetic diversity is important to understand the dynamics of the genetic resources and to improve and sustain sorghum productivity. The main aim of this study was to assess the extent and structure of diversity in sorghum landraces from Kenya. Phenotypic and genotypic data was used to assess diversity in 148 entries consisting of accessions from Western, Turkana, Coast and Eastern regions and breeders lines. Morphological characterization showed high yields among the accessions as revealed by the means of panicle branches (43), panicle length (21cm), and grain weight (1.5g). Late maturity was also observed as shown by the mean number of days to 50% flowering (88 days). Positive correlations were found between all the traits except with days to 50% flowering. All traits showed significant differences. Number of panicle branches had the highest Broad-sense heritability of 0.957. The phenotypic PCA scatter plot clustered the accessions into three groups while the cluster analysis gave two major groups subdivided into four sub-clusters. Molecular characterization using 39 SSR/microsateliite markers gave an average PIC value of 0.54 indicating high polymorphism. The mean diversity index per locus was 0.57. The markers gave a total of 349 alleles (8.9 alleles per locus). In AMOVA all variation components were highly significant (P < 0.001). Diversity among the accessions within the populations was the highest at 56%. The variability within individual accessions contributed 39% and variability among geographical origins contributed only 5% of the total diversity. FST value of 0.05 was observed. A high inbreeding level (Fis = 0.59) and a high heterozygozity deficiency (FIT = 0.61) were observed showing an increased degree of allele fixation and high homozygosity. The genotypic cluster analysis grouped the accessions into three clusters, with a genetic distance range of 0.4 to 0.8. PCoA separated the accessions into three groups. Over all, the study revealed a high diversity among the different sorghum germplasm from Kenya. However, there was no appreciable genetic difference between the sorghum sub-populations.