Genetic diversity analysis in sorghum germplasm collections from Eastern Africa as estimated by morpho-agronomical and SSR markers

[摘要] English: Eastern Africa, where sorghum is a significant arable crop, is arid and areas are at risk of desertification. Consequently, many valuable landraces of sorghum are at risk for genetic erosion. Genetic diversity plays a vital role in the success of any breeding programme. This study aimed to investigate the genetic diversity and genetic relationships in germplasm accessions among east African countries using morpho-agronomical and simple sequence repeat (SSR) markers in order to (i) understand the extent of genetic variation in different countries, and (ii) quantify the genetic structure and how the diversity is distributed among and within countries. The extent of regional patterns of phenotypic diversity was assessed in 1013 accessions using 13 qualitative and five quantitative traits. A total of 1108 sorghum accessions from Sudan, Kenya, Uganda, Ethiopia, Eritrea, Rwanda, and Burundi were assessed using 39 SSR markers. Results on qualitative and quantitative traits data showed that there was a high level of morpho-agronomical diversity among accessions studied. Analysis of variance revealed highly significant differences between accessions pooled over countries and between countries. Based on SSR data, Sudan had the highest genetic diversity and Rwanda the lowest. Levels of genetic diversity differed significantly, with most of the diversity being partitioned more within than between countries. Results suggested that despite sorghum‟s predominantly autogamous mating system, countries clustered totally separately with almost no integration and therefore emphasized the role of farmers�?practices in the preservation of landrace identity and the favouring of genetic diversity. The morpho-agronomical and molecular marker data showed a high level of variation among accessions, and indicated that sorghum populations studied were a mixture of a large number of different genotypes. Therefore, future germplasm collection should take all levels of variation into consideration.

[发布机构] University of the Free State