Morpho-agronomical and molecular marker based genetic diversity analyses and quality evaluation of sorghum [Sorghum bicolor (L.) Moench] genotypes

[摘要] English: Sorghum is the most important cereal crop providing food to millions of peoplein the world. It is well known for its adaptation to harsh environments,specifically to drought and heat stresses, which accounts for its successthroughout the semi-arid regions of the world. Africa, specifically the northeastquadrant of Africa is believed to be the primary centre of origin anddomestication of the crop. In these parts of Africa, genetic variability isavailable both in cultivated races and the wild progenitors. In regard tosorghum utilization in general, developing countries use it primarily as food,whereas developed countries use it as feed. A wide variety of traditional foodsare used from sorghum in the semi-arid tropics.Despite its importance, the genetic characterization of sorghum is very limited.The accurate estimation of genetic diversity of the species is important forconservation of valuable resources and possible future use in its improvement.Farmers' varieties or landraces (locally adapted populations bred throughtraditional methods of direct selection) are usually the major sources of geneticvariation. Cultivated sorghums in Ethiopia show diverse morpho-agronomicdiversity, and have not been studied using the recently developed molecularmarkers. The aim of this study was to estimate genetic diversity by using DNAmarkers, morpho-agronomical traits and food quality attributes in sorghumaccessions.Forty-five accessions, including landrace collections, breeding materials andimproved cultivars from the eastern highlands of Ethiopia were used. A total of552 and 43 polymorphic AFLP and microsatellite alleles, respectively werescored and used to calculate pair-wise genetic distances and clustering. Inaddition, 10 qualitative and 16 quantitative traits with 96 variants were scoredand used to analyse the genetic distances and clustering. The physical andchemical composition and food (injera)-making qualities of selected sorghumsamples were also investigated. A high phenotypic, chemical and geneticvariability among the accessions was observed.The resulting knowledge of genetic distance and discrimination of sorghumaccessions, chemical composition variability and injera-making quality in thisstudy will contribute towards sorghum improvement programmes in Ethiopia,and conservation of novel genotypes. It permits an organization of germ plasmresources and identification of parents for crossing blocks. This will enable thebreeder/ improvement scientist to make more scientific based choices. Thesefindings have shown that both AFLP and microsatellite techniques can besuccessfully used and that they are informative in estimation of geneticdiversity and identification of sorghum accessions. The result from morphoagronomicaltraits analysis generally agreed with the molecular marker resultsin estimating diversity, hence it can be used in the management of sorghumgenetic resources. A further extensive investigation of Ethiopian sorghumgenetic diversity including wider areas and more samples is recommended.

[发布机构] University of the Free State