Water limitation can lead to changes in the turgor of plant cells and tissues which in turn can influence their growth. Plants respond to changes in turgor through rapid molecular and physiological responses and longer-term developmental changes. Changes in gene expression underlie many such responses and are fundamentally important to plant success both in natural populations and in crops. We have developed experimental systems to transiently decrease cell turgor by rapidly changing leaf transpiration and measured genome-wide responses in gene expression to uncover genetic determinants of turgor-sensing and responses to change in turgor.
We have applied novel statistical modelling approaches to pinpoint the timing and trajectory of gene expression at the level of RNA isoforms in response to changing leaf turgor. These approaches have uncovered differential expression of RNA isoforms for hundreds of genes that potentially underlie rapid responses to water limitation and changes in turgor throughout the leaf. Although the prevalence of RNA isoforms is widely recognised, how diverse isoforms facilitate stress adaptation in plants is poorly understood. We have selected candidate genes for functional characterisation of RNA and protein isoforms in response to changing turgor. Our results demonstrate that RNA isoforms contribute to protein diversity, as well as impacting post-transcriptional regulatory processes. We are applying our findings from Arabidopsis to uncover conserved gene regulation networks in diverse plants to reveal evolutionary and adaptive aspects of these responses to water deficit.