50 year-old mystery in plant breeding solved
An international collaboration by researchers from the University of Adelaide’s Waite Campus, France and the Czech Republic has solved a half-century-old mystery in cereal plant breeding, discovering one of the key mechanisms of how wheat chromosomes pair and recombine during meiosis.
Contributions from PhD’s of the early 2000’s, along with the more recent final pieces of the puzzle were contributed by Dr Ute Baumann, Affiliate Associate Prof. Tim Sutton (SARDI) and Dr Ryan Whitford, closing a chapter on more than three decades of research at the Waite Campus. Much of the work on campus was carried out in the Laboratory of Emeritus Prof. Peter Langridge, with contributions from senior scientists, postdocs and PhD students, all leading towards the final gene discovery.
The research published in Nature Communications demonstrates the strength gained from international partnership, in addition to what can be achieved through complementary approaches in cytogenetics, molecular genetics and genomics.
The large size and significant complexity of the wheat genome has intrigued plant geneticists for many years. Wheat has a genome size almost 40 times bigger than rice. It is a hexaploid, made up of three closely related but independently maintained sets of chromosomes, or genomes. During meiosis however, wheat behaves like a diploid, whereby chromosomes only of the same genome pair and recombine. This process is genetically controlled, with one of the main regulators named Ph2 (Pairing homoeologous 2).
The Ph2 gene has long been of interest in plant breeding; because if this regulation of pairing and recombination can be manipulated and relaxed, it would provide an opportunity to successfully generate wide crosses of bread wheat with diverse Triticum species, thus enabling the introgression of new and agronomically relevant genes that would assist with new variety development. Mutants of the Ph2 gene have indeed been used in plant breeding since the early 1970’s, but until now the gene and molecular function were unknown.
The discovery provides fundamental opportunities for wheat genetic improvement, providing a means to access and utilise valuable genetic diversity and overcome one of the major bottlenecks in crop improvement.
