A great proportion of the genetic variation in the species Sorghum bicolor (L.) Moench lies unexploited in wild material. Because this material is small-seeded, shattering and possesses other undesirable traits, it is not easy for plant breeders to make use of it particularly in small breeding programs with the primary objective of variety release in the short to medium term. This project will develop two nested BCNAM populations incorporating the variation of at least 10 diverse Crop Wild Relatives (CWRs) which will provide breeders with access to potentially useful wild sorghum genes in backgrounds that are more amenable to use in breeding. In addition the populations will be characterised with molecular markers allowing the location of useful genes to be quickly identified.
A great proportion of the genetic variation in the species Sorghum bicolor (L.) Moench lies unexploited in wild material. Wild Sorghum bicolor subsp verticilliflorum is found virtually throughout Africa and is known to include considerable morphological and ecological variation. In addition, over much of the same geographical range, there are wild sorghums derived from uncontrolled interbreeding between the wild and cultivated sorghums. These are classified as S. bicolor nothosubsp. drummondii. Because this material is small-seeded, shattering and possesses other undesirable traits, it is not practical parental material for small breeding programs with the primary objective of variety release in the short to medium term. It is inevitable that the wild sorghums in the primary genepool possess genetic variation that is of value to sorghum breeding programs worldwide, indeed there are pre-breeding programs (in Australia and ICRISAT) that have made constructive use of this variation.
The Australian public sorghum pre-breeding team has demonstrated ability in developing back-cross populations with wild sorghum accessions; leading to both published genetic architecture of traits and the licensing of the introgressed material by commercial breeding programs. This project will take at least 10 sorghum CWR accessions and introgress them primarily into two cultivated sorghum backgrounds –a two dwarf genotype grown widely in the dry lowlands of East and Southern Africa (Macia) and a three-dwarf type adapted to mechanized grain production and some crosses to an improved one-dwarf type with broad adaptation in the Sudan Savannah of West Africa. The ultimate target of this project is a panel of between 1000 to 2000 BCNAMs that will be a resource for future Nested Association Mapping and breeding for important adaptive traits in sorghum. There will be a corresponding database of genotypic information and phenotypic information (propensity to tiller, downy mildew, Striga resistance, rust and other foliar disease reaction).
The outputs of the project will include: