Proteome analysis of Physcomitrella patens exposed to progressive dehydration and rehydration

Abstract

Physcomitrella patens is an extremely dehydration-tolerant moss. However, the molecular basis of its responses to loss of cellular water remains unclear. A comprehensive proteomic analysis of dehydration- and rehydration-responsive proteins has been conducted using quantitative two-dimensional difference in-gel electrophoresis (2D-DIGE), and traditional 2-D gel electrophoresis (2-DE) combined with MALDI TOF/TOF MS. Of the 216 differentially-expressed protein spots, 112 and 104 were dehydration- and rehydration-responsive proteins, respectively. The functional categories of the most differentially-expressed proteins were seed maturation, defence, protein synthesis and quality control, and energy production. Strikingly, most of the late embryogenesis abundant (LEA) proteins were expressed at a basal level under control conditions and their synthesis was strongly enhanced by dehydration, a pattern that was confirmed by RT-PCR. Actinoporins, phosphatidylethanolamine-binding protein, arabinogalactan protein, and phospholipase are the likely dominant players in the defence system. In addition, 24 proteins of unknown function were identified as novel dehydration- or rehydration-responsive proteins. Our data indicate that Physcomitrella adopts a rapid protein response mechanism to cope with dehydration in its leafy-shoot and basal expression levels of desiccation-tolerant proteins are rapidly upgraded at high levels under stress. This mechanism appears similar to that seen in angiosperm seeds.

Can mosses serve as model organisms for forest research?

“…At the transcript as well as at the protein level, chaperones such as LEA (late embryogenesis abundant) proteins, also called dehydrins or rehydrins, play prominent roles, though their exact molecular function is often still unclear. Later during land plant evolution, LEA protein function was probably adapted to the desiccation of seeds (Cui et al 2012;Oliver et al 2005). Functional studies of mutants confirmed the importance of some dehydrins in the moss response to salt and osmotic stress (Ruibal et al 2012;Saavedra et al 2006).…”

“…P. patens is dehydrationtolerant but can become desiccation-and freezing-tolerant by pre-treatment with ABA (Khandelwal et al 2010;Nagao et al 2005). Whereas abiotic stress signaling seems largely conserved between mosses and flowering plants (Khandelwal et al 2010;Komatsu et al 2013;Richardt et al 2010), several studies report on so-called orphan, non-characterized stress responsive moss genes and proteins (Beike et al 2015b;Cui et al 2012).…”

“…To date, most attention has been paid to the mechanisms by which mosses master the cellular challenges during dehydration/rehydration and freezing, sometimes also employing ABA or salt treatment (Cui et al 2012;Cuming et al 2007;Hiss et al 2014;Nagao et al 2005;Oliver et al 2005). Results include the avoidance of stress by downregulation of photosynthesis (Cuming et al 2007;Hiss et al 2014) and the rapid upregulation of protective mechanism for photosynthesis, membranes and protein folding (Azzabi et al 2012;Hiss et al 2014;Ruibal et al 2013).…”

Plant Desiccation Tolerance and its Regulation in the Foliage of Resurrection “Flowering-Plant” Species

“…A putative member of the PEBP family of proteins increased 9-fold in abundance in drying plants of the desiccation-tolerant moss Physcomitrella patens (Hedw.) Bruch & Schimp [58].…”

Identification of Targets and Interaction Partners of Arginyl-tRNA Protein Transferase in the Moss Physcomitrella patens

“…Further, the axenic cultivation of different growth states under highly standardized conditions facilitates reproducible high throughput analysis of proteomes, transcriptomes, and metabolites (35)(36)(37)(38)(39)(40)(41). Recently, we reported that ATE abundance underlies spatiotemporal patterning in the moss Physcomitrella patens using a translational GUS reporter fusion via knock-in at the endogenous genomic locus (11).…”