Molecular evaluation of Ethiopian sweet sorghum germplasm and their contribution to regional breeding programs

Abstract

Sweet sorghum is an excellent feedstock for ethanol production and is also used for food and livestock feed. Germplasm collection and characterization in sweet sorghum is a crucial step towards breeding and development of superior genotypes for various enduses. In the present study, 13 Simple Sequence Repeat (SSR) markers were used for genotyping 175 Ethiopian s weet sorghum accessions alongside 27 improved accessions from eastern and southern Africa. All the tested markers detected 159 alleles and a high polymorphism information content (PIC) averaging 0.69. A comparison between Ethiopian and improved accessions revealed higher allele numbers (124) in Ethiopian than improved accessions (92 alleles). More than half (65 out of 124) of the alleles observed in the Ethiopian accessions were rare (<5%) and 64 were private (only present within Ethiopian accessions) while in the improved accessions, 41% and 38% of the alleles detected were rare and private respectively. Both weighted Neighbor Joining-based clustering and hierarchical clustering grouped the 202 accessions into three major clusters based on geographical origin. Ethiopian accessions from the north (north Wello and south Tigray) not only clustered separately from accessions from the west central and eastern Ethiopia, but were also distinct from most of the improved genotypes. Our results reveal an unexploited highly diverse sweet sorghum genetic resource from Ethiopia that can be included in the regional breeding programs in order to efficiently optimiz e productivity.

Screening, compiling and validation of informative microsatellite sets for marker-assisted breeding of key Ethiopian sorghum cultivars

“…Similarly, second highest frequency (29%) was observed for allele size ranged from 151 to 200 bps followed by allele sizes between 100 to 150 bps between ranging (Table 1). In general, the majority of the screened polymorphic markers (94%) allele sizes ranged from 100 to 300 bp which is in agreement with many studies undertaken in the past (Bhattramakki et al, 2000;Kong et al, 2000;Menz et al, 2002;Scholes et al, 2002;Wu et al, 2006;Ramu et al, 2009Disasa et al, 2016a. Besides, most of the markers that their fragment sizes lie in this range showed clear and longer beaks while scoring using GenMapper software (Fig 1) indicated that they should be the choice of marker for the application in sorghum improvement programs.…”

“…The computed average PIC value (0.53) in this experiment was very close to most of the previously reported values using both grain and sweet sorghum (Agrama and Tuinstra,2003;Caniato et al, 2007;Ali et al, 2008;Wang et al, 2009;Ramu et al, 2013). However, the result was somewhat lower than the average PIC value reported in wild sorghum (Muraya et al, 2011;Adugna et al, 2012) and sweet sorghum (Disasa et al, 2016a) populations. This is possibly due the polymorphic nature of the selected SSR markers used for genotyping as well as type of germplasm studied.…”

“…Besides, the discovery of known stay-green genotypes (E 36-1, B 35) possessing novel genes for drought tolerance traits (Haussmann et al, 2002;Harris et al, 2007;Reddy et al, 2009) is a good demonstration of the importance of Ethiopian sorghum accessions in crop improvement. Besides, there is high genetic diversity among Ethiopian sweet sorghum accessions (Disasa et al, 2016a) which are characterized by high sugar content (Disasa et al, 2016b). This is a potential area to be used in bioethanol production as well as animal feed.…”

“…Large numbers of SSR primers have been assembled in the public domain that can be used for various purposes such as diversity analysis, construction of linkage and QTL mapping, marker assisted selection and other related activities (Brown et al, 1996;Bhattramakki et al, 2000;Kong et al, 2000;Schloss et al, 2002;Menz et al, 2002;Wu et al, 2006;Li et al, 2009;Ramu et al, 2009). However, most of them developed using exotic germplasm with very few number of sorghum genotypes of Ethiopian origin (Beyene et al, 2014;Disasa et al, 2016a). Therefore, there is a need to screen and compile the most polymorphic markers that can be used for marker assisted selection in the future using selected Ethiopian sorghum genotypes.…”

Genotypic variability and relationships of Sorghum bicolor accessions from Java Island, Indonesia based on IRAP markers

“…Sorghum bicolor (L.) Moench is a member of the Poaceae family and considered as multi-beneficial crop with various uses. The grains are used for food, the leaves are used as animal feed, and the stem with high sugar content is processed for syrup, beverage, and biofuel (Dahlberg et al 2011, Disasa et al 2016. Accordingly, three variants of S. bicolor are known namely grain sorghum, forage sorghum, and sweet sorghum.…”