New resistance genes from wild species for Australian wheats
GroundCover™ Issue: 46
THE SUCCESS of the ACRCP depends largely on the deployment of effective resistance genes in areas at risk from rust invasion. With the recent losses of several important sources of rust resistance to new virulent rust strains, researchers at the University of Adelaide's Waite Campus and the CSIRO Division of Plant Industry are actively searching for new genes to incorporate into new wheat varieties for Australia.
The Adelaide team includes Ian Dundas and Dawn Verlin, who are targeting the wild grass relatives of wheat for new resistances. Rust-resistance genes from wild relatives of wheat have long been a valuable mainstay of Australian wheats, and have been used in many cultivars (e.g. Janz, Nyabing, Sunvale, Giles).
The Adelaide team has searched the world (with assistance from Dr Rafiqul Islam, Adelaide University) for wild species with resistance to stem, leaf and stripe rusts. Over 30 accessions of species of Triticum and Thinopyrum were then imported from Israel, the USA and Canada and local work at PBI Cobbitty confirmed their rust resistance. Several lines with the highest levels of rust resistance are now being targeted for further work.
Dr Dundas and Ms Verlin are also targeting several chromosome segments carrying resistance genes that were transferred to wheat from wild grass species by other researchers. These resistances have never been released in commercial cultivars because of their associations with yield and quality defects. The Waite team are trying to develop new stocks with the rust-resistance genes but lacking the undesirable traits.
Similar research at CSIRO in Canberra is also yielding benefits for wheat producers. Some years ago Phil Larkin and Phillip Banks (now at the Leslie Research Centre, Toowoomba) located a strong source of resistance to barley yellow dwarf virus (BYDV) in the grass Thinopyrum intermedium. The resistance was transferred to wheat using cell culture techniques. The first cultivar with this resistance, the world's first BYDV-resistant wheat, is the dual-purpose winter wheat Mackellar, developed by CSIRO.
Dr Larkin and his team are now exploiting another alien translocation from Thinopyrum elongatum that carries two potentially valuable rust resistances, Lr19 and Sr25. These genes have not been used in Australia because of an association with a gene causing extreme yellow flour. By luck, the Lr19 resistance and the BYDV resistance found earlier are on the same wheat chromosome arm. Attempts are being made to combine the best genes from the two Thinopyrum species and to eliminate the deleterious genes.
Program 3 Contact: Dr Ian Dundas 08 8303 7238 email email@example.com
Program 3 Contact: Dr Phil Larkin 02 6246 5060 email Philip.Larkin@csiro.au