Unravelling the genetic complexity of sorghum seedling development under low-temperature conditions

Abstract

Sorghum is a promising alternative to maize for bioenergy production in Europe; however, its use is currently limited by poor adaptation to low temperatures during and after germination. We collected multi-trait phenotype data under optimal and suboptimal temperatures in a genetically diverse recombinant inbred line (RIL) mapping population showing contrasting segregation patterns for pre- and post-emergence chilling tolerance. Germination, emergence, seedling development, root architecture and seedling survival were assessed in two different seedlots. Emergence and root establishment were found to be the key determinants of development and survival under chilling stress. Highly interactive epistatic quantitative trait loci (QTL) hotspots, including a previously unknown QTL on Sb06 with a significant effect on prolonged chilling survival, were found to regulate different physiological mechanisms contributing to maintenance of growth and development despite the chilling temperatures. The major QTL regions harbour promising candidate genes with known roles in abiotic stress tolerance. Identification of loci in the QTL hotspot regions conferring maintenance of cell division and growth under early chilling stress represents a promising step towards breeding for successful establishment of sorghum in temperate climates. Sorghum is a promising alternative bioenergy crop for temperate climates, however its use is limited by poor adaptation to low temperatures during and after germination. This study dissected the genetic complexity of multiple traits contributing to pre- and post-emergence chilling tolerance in a segregating sorghum population. Emergence and root establishment were identified as key determinants of development and survival under low-temperature stress. Epistatic QTL hotspots were found to regulate different physiological mechanisms for growth maintenance under chilling temperatures. © 2013 John Wiley & Sons Ltd.