Modelling Leaf Growth and Transcriptional Response of Perennial Ryegrass to Drought Stress

Summer droughts are becoming increasingly common which limit growth in perennial ryegrass. While the growth of leaves has been studied in relation to temperature, the impact of reduced water availability has received little attention. Furthermore the molecular mechanisms regulating growth under water limitation are largely unknown. Here we sought to identify key physiological changes, resulting from drought, and correlate these with transcriptome changes in the meristem. We constructed a model to identify when a plant limits and stops leaf elongation as a consequence of water limitation. This was coupled with transcriptome profiling of the meristem over five days at three times per day, to provide high resolution chronological molecular profiling. By combining both physiological and molecular data, we provide first clues into gene networks controlling growth in perennial ryegrass under abiotic stress. These data provide a rich resource of candidate genes for crop improvement. The results can be used to refine quantitative trait loci regions and identify their underlying causal genes. The relatively rapid screening involved to phenotype growth under water limitation is also applicable to improve yield of perennial ryegrass under summer droughts through selection.