Global food security represents a major challenge for modern agriculture, particularly within the context of climate change. In addition, pressure is increasing on available water resources, and reduced soil water availability often causes substantial decreases in crop biomass and yield. Therefore, it is a research priority to develop solutions for more sustainable use of water in agriculture. One possibility could involve targeting the signalling pathways involved in plant water use and development. Circadian rhythms regulate stomatal movements and increase water use efficiency (WUE) (Dodd et al. (2004, 2005)), and sucrose non-fermenting1-related kinase1 (SnRK1) is a central regulator of energy signalling, but the mechanisms underpinning these processes and their contributions to plant performance remain unclear. Using Arabidopsis thaliana (Arabidopsis) as my model system, I focused on elucidating roles of the circadian clock and SnRK1 signalling pathways in regulating WUE and physiology. I demonstrated that the circadian clock regulates whole plant WUE under diel conditions, and identified several circadian oscillator components that make key contributions to WUE. I generated and validated transgenic Arabidopsis with misregulated guard cell circadian clocks, then isolated guard cell-dependent and independent effects of the circadian clock upon whole plant physiology. In addition, I identified possible roles for other tissue-specific circadian clocks in regulating physiology, by comparing these transgenic genotypes with whole plant circadian clock gene overexpressors. Using a naturally-occurring population of Arabidopsis halleri subsp. gemmifera, I also detected rhythms of stomatal movement under field conditions, as well as a possible trade-off between stomatal and trichome development. Finally, I determined novel roles for SnRK1 in regulating WUE and sucrose-induced hypocotyl elongation. Overall, this thesis contributes to our understanding of the mechanisms underlying plant water use and development, and may inform future research and breeding efforts.
|Date of Award||9 Nov 2018|
- The University of Bristol
|Supervisor||Antony Dodd (Supervisor) & Alistair M Hetherington (Supervisor)|