BRC-BIO: Which whole-plant traits facilitate desiccation tolerance in the vegetative tissues of terrestrial and epiphytic resurrection ferns?

Pepperdine University, Malibu CA

Investigators

Abstract

Resurrection plants can lose nearly all of their water to enter a dormant, dry state and subsequently regain their original function when rehydrated. Scientists have begun to characterize the molecular mechanisms of recovery at the tissue level, but little is known about larger scale traits that enable recovery at the level of the whole plant. This project will attempt to discover those key traits by comparing the structure and function of closely related resurrection and non-resurrection plants. Land-dwelling and tree-dwelling resurrection plants will be compared in order to better understand which traits are common to all resurrection plants and which traits are specific to a given habitat. High resolution x-ray technology will be used to visualize the movement of water through resurrection and non-resurrection plants during rehydration. Knowledge of the traits that enable recovery in resurrection plants will improve the current understanding of plant drought tolerance and inform ecological management of resurrection plants. This knowledge might also be used to assess the potential for developing crops that are more drought tolerant. This project aims to provide insight into the evolution of whole-plant desiccation tolerance (DT) by systematically determining traits enabling whole-plant recovery in six DT lineages of ferns and lycophytes. Anatomical and physiological traits related to water use will be assessed in hydrated plants, comparing closely related DT and non-DT species. During dehydration and rehydration, high resolution micro-computed tomography (microCT) will be used to assess timing and level of recovery in distal tissues. Vascular DT plants will likely exhibit varied mechanisms of recovery according to their habitat, with terrestrial (land-dwelling) plants resurrecting by means of root pressure and epiphytic (tree-dwelling) plants recovering via foliar water uptake. However, other traits will likely be shared among all DT ferns and lycophytes, such as traits that maintain structural integrity in the dry state and traits that facilitate timely desiccation. Including both sporophytes and gametophytes in this comparison will provide a holistic perspective on fitness and trait coordination between life history stages. Furthermore, DT ferns represent a neglected opportunity to learn about DT adaptations to the epiphytic habitat and its varied ecological niches. This study will elucidate how DT has been co-opted for fern survival in the epiphytic habitat, broadening our understanding of both ferns and epiphytes. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.