GNPS - Label free proteomic and complementary metabolomic analysis of leaves of the resurrection plant Xerophyta schlechteri during dehydration

Vegetative desiccation tolerance, the ability to survive loss of ~ 95% relative water content (RWC) is rare in angiosperms, these being commonly called resurrection plants. It is a complex multigenic and multi-factorial trait, its understanding requiring a comprehensive systems biology approach. The aim of the current study was to conduct a label-free proteomic analysis of leaves of the res-urrection plant Xerophyta schlechteri in response to desiccation. A targeted metabolomics approach validated and correlated to the proteomics, contributing the missing link in studies on this species. Three physiological stages were identified. An early response to drying, during which the leaf tissues decline from full turgor to a relative water content (RWC) of ~ 80 - 70%, a mid-response in which RWC declines to 40% and a late response where tissues decline to 10% RWC. We identified 517 distinct proteins that were differentially expressed, of which 253 proteins were upregulated and 264 were downregulated in response to the three drying stages. Metabolomics analyses, which included monitoring levels of a selection of phytohormones, amino acids, sugars, sugar alcohols, fatty acids and organic acids in response to dehydration, correlated with some of the proteomic differences, giving insight into the biological processes apparently involved in desiccation tol-erance of this species.