Genetic Relationships of Sorghum Germplasm in Asia and Africa Revealed by Rice cDNA-STS and Indel Markers

The elucidation of Sorghum bicolor intraspecific genetic diversity is of interest in studies on evo- lutionary forces under domestication and geographical distribution, and has application in the de- sign of programs for conservation, management and uses of genetic resources in breeding pro- grams. Since molecular markers enable assessment of genetic relationship, various types of mark- ers have been developed in many investigations of crops. This work aimed to assess the level of genetic diversity in grain sorghum collected from different regions in Asia including Central Asia and Africa. For the purpose, 14 rice cDNA-STS and 10 insertion/deletion (Indel) markers have been used. The majority of genes tagged by these markers were genes of complex crucial en- zymes of cellular metabolism and stress-inducible proteins. Based on the markers, 48 sorghum ac- cessions selected from the collection in NIAS Genebank (Tsukuba, Japan), and those from the All-Russian Research Institute of Plant Industry (St. Petersburg, Russia) were analyzed using clus- ter and principal coordinate analyses. The results demonstrated the existence of three major geo- graphical centers for sorghum evolution and differentiation. Two of the centers are found in the African continent where sorghum is suggested to have been domesticated. Asian sorghums are grouped in a geographical cluster distinctive from the African groups. More precisely, there are separate sub-groups of accessions originating from East Asia and Central Asia, respectively. This is the first report of the Central Asian sorghum cultivars forming a unique genetic group. The va- riety groups demonstrated here may provide important information on phylogenic differentiation of this crop in Asia and Africa. This work demonstrated that rice cDNA-STS and Indel markers are useful instruments for evaluation of sorghum genetic diversity.