Our work stems from an interest in understanding how plants respond to limited and variable water availability. Adaptive mechanisms to cope with water stress are highly relevant in light of current and predicted climate change. Dehydration tolerance (DhT, also dehydration tolerant) is a relatively rare strategy for coping with water shortage that allows tissues to survive substantial cellular drying. This adaptation provides a unique opportunity to identify key genes, physiological, and ecological traits that will inform management and biotechnological advances aimed at reducing agricultural and ecological damage due to drought. Marchantia inflexa, a DhT tropical liverwort is currently undergoing range expansion and colonizing novel habitats, likely facilitated by its ability to acclimate to these novel conditions. However, older populations also exist across a variety of habitat types and these populations could harbor genetic adaptations in DhT. To test for adaptive differences between M. inflexa populations, plants were collected from two habitat types, which differ in relative water availability. The DhT of these plants was tested in the field to assess habitat acclimation. Plants were then cultured in a common garden for six months, and assayed again to screen for genetic differences in DhT of these groups.
Results/Conclusions
Our recent studies indicate that M. inflexa exhibits moderate and variable levels of DhT, and has the capacity to acclimate to different climatic moisture levels, suggesting that there is a plastic component to DhT in this species. In addition, we recently demonstrated that males of M. inflexa species are significantly less DhT than females, and that the vegetative meristem is more DhT than the non-meristematic vegetative tissue. Based on these two observations we designed and conducted an RNA sequencing study to characterize changes in gene expression during dehydration and rehydration in these tissues in male and female plants. Consequently, we were able to identify genes with different expression profiles across samples. These genes were then implicated as candidate genes contributing to underlying differences in DhT. By taking a within species approach, we were able to minimize background differences and identify a high-resolution set of candidate DhT genes. Furthermore, the resulting transcriptome provides a valuable resource for other researchers wanting to compare sensitive species or highly desiccation tolerant species to the more intermediate phenotype of a DhT plant.