Genetic characterisation and mathematical modelling of speed-breeding plasticity in barley.

With changes in population demographics, urbanisation and the declared climate emergency in Scotland there is a need to use resources more sustainably. The importance of breeding climate resilient crops has never been greater. Various approaches built around the deployment of disruptive technologies (Hickey et al 2017) have been proposed to increase the pace and precision of breeding. One such technology is speed breeding which is designed to accelerate plant development, particularly flowering time based on extended light regimes (Watson et al. 2018). Although the concept is empirically well advanced the underpinning biology and potential disruption of the circadian clockwork and photoperiod pathways is poorly understood. Plant breeders regularly manipulate light and temperature to reduce generation time and hasten the breeding cycle through the adoption of single seed descent approaches. This approach may have introduced unconscious selection for speed-breeding responsive types. Preliminary data obtained at SRUC have confirmed that there are genetic differences between modern barley varieties developed through accelerated breeding and older varieties and land races in their response to speed breeding regimes. These observations provide the experimental framework to identify the key genetic determinants of speed breeding and the consequences of selection on clock associated components and genomic plasticity in an economically important crop, barley. Furthermore, unravelling the genetics of plasticity to speed breeding brings the opportunity to deliver step changes in the breeding of climate resilient crops.
We propose to identify key determinants of speed-breeding plasticity. We will use barley as a model for ecological adaptation and an important crop for Scotland. Modern elite barley germplasm along with older varieties that are less likely to have undergone unconscious selection from rapid cycling breeder interventions will be screened for speed breeding plasticity. This will be measured by extent of reversion to normal growth after exposure to a speed breeding environment. Our preliminary data indicate that variation in plant responses ranging from continued rapid development to reversion to normal rates of developmental will be detected. This plasticity will be mapped by methods such as next generation sequencing of the extreme bulks. Additionally, system biology approaches (Chew et al. 2017) will be deployed to provide further and deeper understanding of the response to speed breeding. Overall, we aim to move our understanding of speed breeding from an empirical approach to a predictive enabling technology that can be directly applied in pre-breeding where little is known about the consequences of selection on genome plasticity.
This project will provide interdisciplinary student training in modern plant breeding mathematical and systems biology. Training in plant breeding and quantitative genetics will be provided through our group in SRUC, and training in systems biology and mathematical modelling will be available through our project partner, Prof. Karen Halliday, University of Edinburgh (UoE), further enhancing the training of the student.
References
Watson et al. (2018) Speed breeding is a powerful tool to accelerate crop research and breeding. Nature Plants 4: 23-29.
Chew et al. (2017) Multi-scale modelling to synergise plant systems biology and crop science. Field Crop Research 15: 77-83.
Hickey et al. (2017) Genomic prediction unifies animal and plant breeding programs to form platforms for biological discovery. Nature Genetics 49(9): 1297-1303.