Using ‘speed breeding’ to harness rust resistance: faster, cheaper and easier
A new method for rapid generation advance, called ‘speed breeding’, has considerable advantages over DH technology for spring wheat because it provides increased recombination during line development and enables selection in early generations for some traits. The system has been refined over the past 8 years at The University of Queensland, utilizing controlled temperature regimes and 24-hour light to accelerate plant growth and development. The low-cost management system enables up to 6 plant generations of wheat annually – just like Arabidopsis. Currently, three of the six wheat breeding companies in Australia are exploiting speed breeding, and elite lines developed using the technology are in the final stages of yield evaluation. Recently, we developed methods adapted for use in the speed breeding system, which permit year-round high-throughput screening for adult plant resistance (APR) to rust pathogens that attack wheat. In this presentation, we describe the protocols, explain how phenotypes are related to field-based measures and highlight how the system can even handle diverse germplasm, such as winter types and landraces. Our ‘triple rust’ screening methodology enables selection for APR to all three rust pathogens and crossing of selected plants within a single plant generation. We applied the technique to rapidly introgress rust resistance into several Australian cereal cultivars. The technology is also a useful tool to accelerate rust research efforts. RIL populations designed for mapping novel APR genes can be developed within 12–18 months. Experiments to understand gene function in terms of temperature stability and onset of resistance can be performed year-round and if combined with sequencing technologies, such as RNAseq, transcripts involved in rust defence can be rapidly identified and harnessed via the speed breeding system. We will also reveal our current activities aiming to integrate the system with other plant breeding technologies to maximise genetic gain for wheat.