High-Density Multi-Parent Genome Mapping in Sorghum

Sorghum (Sorghum bicolor (L.) Moench) is a promising candidate as alternative to maize as resource for bio-energy production in Europe. Until now cultivation in Europe is limited by the susceptibility of sorghum seedlings to chilling temperatures. Within the multinational European project ERANET-GAS (Genomic Adaptation of Sorghum) we are developing and applying genomic tools for bio-energy sorghum breeding towards chilling tolerance. Chilling tolerance is a complex trait with a strong dependency on root architecture and consequent interactions with water-use and nutrient-use efficiency. Based on four genetically divergent sweet and grain sorghum lines (M71, SS79, Etian, Ji273) we developed a new interrelated meta-population (IMP) comprising over 600 recombinant inbred lines (RILs). These are being subjected to deep phenotyping of root architecture, nutrient responses, stress physiology, disease resistance and germination behaviour, and will be further characterised for architectural traits, field emergence and yield performance. The IMP-RILs were genotyped using a new 90k Affymetrix Axiom array, also generated within the consortium. Integrating genetic data of the IMP with physical positions of the SNP markers, we developed a high resolution recombination map of the sorghum genome. High-resolution mapping of quantitative trait loci (QTL) using this large, multi-parent population will uncover tightly linked markers and genes associated with important traits for breeding of European energy sorghum. The data also form a basis for future genomic selection strategies to improve energy yields.