PEGASUS: Prediction and Exploitation of Genebank Accessions. A Study in Ugandan Sorghum

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Efficient utilisation of crop genetic resources is becoming increasingly important in order to breed sustainable, resource-efficient crops with increased productivity to feed the growing world population under fluctuating environmental constraints. Modern, high-throughput genomics methods can play a key role in characterising, evaluating and implementing plant genetic resources, however important diversity collections in developing countries often lack the resources to implement genomics tools. For example, Uganda is a major centre of diversity and domestication of sorghum, the most important cereal crop in sub-Saharan Africa and a staple food for millions of people. The Uganda national genebank harbours an extensive, unique collection of 2635 sorghum accessions, including rare landraces and wild germplasm. These materials represent a substantial reservoir of genetic and phenotypic diversity for adaptation of sorghum crops to abiotic and biotic stress factors. However, this diversity has not yet been systematically characterised and evaluated, strongly limiting its utilisation to breed modern sorghum varieties with beneficial traits for farmers.In previous work, the Ugandan partner identified rich diversity for various important traits needed in sorghum improvement in Uganda and elsewhere, including drought, cold and heat stress adaptation, resistance to pests and diseases, superior grain, fodder and nutritional quality. The German partner developed genome sequence resources and a high-density 90k single-nucleotide polymorphism (SNP) genotyping array for sorghum, along with sorghum hybrids for energy and fodder use in European climates. Within the framework of the DFG programme for cooperation with developing countries, this project will utilise these extensive resources to achieve the following scientific objectives:i) A comprehensive genome survey of genetic diversity in the Ugandan sorghum collection;ii) Definition of a representative core collection based;iii) Detailed phenotypic screening of the core collection for key traits, with a focus on drought tolerance as the major limitation for Ugandan sorghum productivity and early-stage cold tolerance as a key limiting factor for German sorghum production;iv) Elucidation of the genetic architecture of target traits;v) Genomic prediction of trait performance in the entire collection to identify valuable genotypes for preservation and breeding.The project presents a practical case study for management and use of valuable genebank collections in developing countries using genomic tools. It will furthermore make an important contribution to the human resource capacity of the Uganda National Genebank in plant breeding and genetics, ensuring technology and knowledge transfer to the African partner country and enabling long-term implementation of the results for African sorghum improvement.