Futureproofing our food: dissecting the drought regulome of bread wheat

Hexaploid bread wheat (Triticum aestivum L.) supplies over half the world with a substantial portion of its daily calories, but a changing climate threatens to disrupt supply. Climate change endangers wheat production through massive perturbations in weather patterns, intensifying and increasing the frequency of droughts, and ultimately jeopardising food security and farmer livelihoods, especially in low- and middle-income regions. Projected population growth to over 9.7 billion people by 2050 compounds these issues, further increasing demand. Our understanding of the regulatory basis of wheat drought responses is limited, especially at the early vegetative stages of growth, and so dissecting this complex response is essential for futureproofing our wheat.

Using the YoGI panel, a collection of over 340 landraces, this thesis seeks to dissect the molecular and physiological responses of wheat seedlings to harsh drought exposure at the transcriptomic and epigenetic levels. Through phenotypic analyses, comparative transcriptomics, weighted gene co-expression network analysis (WGCNA), and whole genome bisulphite sequencing (WGBS), this thesis: characterises the impact of early drought on the wheat transcriptome; explores candidate master regulators of the wheat drought response; identifies candidate master regulators of drought tolerance across wheat landraces; examines the role of drought-responsive DNA methylation in modulating gene expression and transposable element activity; and evaluates the potential effects of within- and across-generation drought priming treatments on drought tolerance in wheat landraces.

By detailing potential mechanisms, key transcriptomic master regulators, and epigenetic signatures associated with the drought response and drought tolerance, this thesis aims to inform future molecular crop breeding programmes that seek to develop more drought-tolerant wheat cultivars.