Genetic Relationship between Sweet Grain Sorghum and the Other Sorghum Types Cultivated in Burkina Faso Assessed with Nuclear Microsatellite Markers SSRs

In Burkina Faso, sweet grain sorghum [Sorghum bicolor (L.) Moench] is generally cultivated in association with several other types of sorghum. However, the lack of information on the genetic relationship between this sorghum and grain sorghum as well as sweet stalk sorghum hinders the efficient management of its genetic resources. Thus, 34 sorghum accessions consisting of 14-grain sorghum, 10-sweet stalk sorghum, and 10 sweet grain sorghum were evaluated using 15 nuclear microsatellites markers (SSRs) to determine their genetic relationship. Results revealed significant genetic diversity within each sorghum type and a significant index of genetic differentiation per pair of sorghum types (0.017) between sweet grain sorghum and sweet stalk sorghum. The minimum Nei distance was also high (0.12) between these two sorghum types. Sweet grain sorghum indeed showed the lowest values of theoretical heterozygosity (0.35), of observed heterozygosity (0.13). Structuring of the accessions of the three types of sorghum cultivated in two distinct groups, one of grain sorghum and sweet stalk sorghum and another consisting of accessions of grain sorghum and sweet grain sorghum was also obtained. The low differentiation observed would suggest greater genetic proximity between the three types of sorghum. The differences observed would be more of a physiological and biochemical nature. These results could contribute to better management of the genetic resources of sweet grain sorghum.