Analysis of the nuclear proteome of the resurrection plant Xerophyta viscosa in response to dehydration stress using iTRAQ with 2DLC and tandem mass spectrometry

Xerophyta viscosa Baker (family Velloziaceae) is a desiccation tolerant plant which survives extremes of dehydration down to 5% relative water content (RWC) and resumes full physiological activity within 80h of rehydration. The nuclear proteome of Xerophyta viscosa and its response to dehydration at 35% RWC as compared to fully hydrated plants was analysed using iTRAQ together with 2DLC and ESI-MS/MS. RWC at 35% is unique for desiccation tolerant species as it represents a distinct phase of the dehydration process where induction of late protection mechanisms are initiated. We reproducibly identified 122 proteins with confidence≥95% (ρ<0.05). In response to dehydration, 65% of the identified proteins had the same protein abundance as the hydrated, 22% were shown to be more abundant while 9.8% were less abundant. Classification of the nuclear proteins according to GO annotation showed that most proteins were part of cellular processes (77.43%) and had binding activity (85.47%) respectively. Ontological classification according to Interpro and Pfam databases categorized most nuclear proteins as part of gene regulation (21%) while the functions of the mapped proteins using MapMan showed involvement in protein synthesis (22%), degradation (9%), DNA structure (8%) and regulation (8%).