Plant & Animal Genomes XV Conference

January 13-17, 2007
Town & Country Convention Center
San Diego, CA

Multi-Population To Mapping To Increase Genetic Diversity And Grain Yield In Sorghum

David R Jordan¹ , Graeme L Hammer² , David Rodgers³ , David G Butler³ , Colleen H Hunt ³ , Bertrand Collard¹ , Emma S Mace ¹

¹  Hermitage Research Station Department of Primary Industries and Fisheries MS 508 Warwick, Qld 4370 Australia

²  2Agricultural Production Systems Research Unit School of Land and Food Sciences The University of Queensland Brisbane, Qld 4072 Australia

³  Department of Primary Industries and Fisheries Tor Street Toowoomba, Qld 4350 Australia

Major advances have been made in the level of stay-green and midge resistance in Australian sorghum. However, the focus on these polygenic defensive traits has contributed to a decline in the genetic diversity in elite parent lines. In contrast to the advances in defensive traits, the rate of genetic gain for grain yield has been modest (~1% per annum). Limited genetic diversity, limited focus on grain yield per se and the prevalence of genotype x environment (GxE) interactions were identified as major constraints to progress for grain yield. In response we have developed a program to increase the yield potential of our germplasm through the introduction of diverse germplasm via a limited backcrossing procedure along the lines of the advanced backcross method. Populations are generated by crossing a number of exotic lines to an elite line and backcrossing the resulting F1 plants to the elite line to produce large Bc1F1 populations. Selection for appropriate agronomic type is carried out through a number of generations of self pollination to BC1F4. Each year 50-80 lines from 20 families are evaluated in F1 hybrid combination with a standard tester at 5-7 locations. A crop simulation modelling approach is being used to interpret and reduce effects of GxE by characterising the testing environments into particular types. Each line is subjected to a whole genome scan using the DArT marker system. A multi-population mapping approach is then employed to identify genomic regions associated with yield and adaptation and the best potential sources of these regions.