Desiccation tolerance of Hymenophyllacea filmy ferns is mediated by constitutive and non-inducible cellular mechanisms.
The Hymenophyllaceae is a primitive family within the Filicopsidae. One of the most exceptional features of this family of ferns is the presence of fronds with one or just a few cell layers (hence their name of filmy ferns), and the absence of stomata. Hymenophyllum caudiculatum and Hymenophyllum dentatum are able to lose more than 82% of their fully hydrated water content, to remain dry for extended periods of time (days or weeks), and to survive and remain viable following rehydration. The aim of this work was to understand whether the adaptive strategy of the Hymenophyllaceae for desiccation tolerance is constitutive or inducible. A proteomic approach was adopted in combination with physiological parameters to assess whether there were changes in the protein content during dehydration and following rehydration. Detached fronds were used to monitor the rates of photosynthesis in desiccation experiments, sugar accumulation, and high-resolution 2-DE to analyze proteome variation during a desiccation-rehydration cycle. The analyzed proteome exhibited little variation (3-4%) between hydrated and desiccated states, while variation was greater between the desiccated and rehydrated states (8.7-10%). Eighty-two discrete proteins were analyzed by MS/MS, and 65 were identified. About 21% of the analyzed proteins (17) were mixtures of two or more different polypeptides. Of the identified proteins, more than a half (33 spots, 55%) had functions related to energy-photosynthesis. The second largest category with known function (five spots, 8%) was related to cell rescue, defense, and virulence. More than one in every four proteins analyzed belonged to a group of hypothetical proteins (18 spots, 28%). The results suggest that the Hymenophyllaceae represent an example of a change in adaptive strategy from a typical vascular to the poikilohydric homoiochlorophyllous adaptation, which they share with the bryophytes that grow in profusion in the same habitats. The speed at which desiccation takes place therefore precludes the induction of protective systems, suggesting a constitutive mechanism of cellular protection.
Departamento de Ingeniería Química, Facultad de Ingeniería, Ciencias y Administración, Universidad de la Frontera, PO Box 54-D, Temuco, Chile; Departamento de Recursos Naturales, Facultad de Ciencias Agronómicas y Forestales, Universidad de la Frontera, PO Box 54-D, Temuco, Chile. Electronic address: marcelo.garces@ufrontera.cl.
Marcelo
M
Garcés Cea
Pôle Protéomique, Plateforme génomique fonctionnelle de Bordeaux, Université Victor-Segalen, Bordeaux-2, 146, rue Léo-Saignat, 33076 Bordeaux, France.
Stephan
S
Claverol
Departamento de Recursos Naturales, Facultad de Ciencias Agronómicas y Forestales, Universidad de la Frontera, PO Box 54-D, Temuco, Chile.
Carla
C
Alvear Castillo
Departamento de Recursos Naturales, Facultad de Ciencias Agronómicas y Forestales, Universidad de la Frontera, PO Box 54-D, Temuco, Chile.
Claudia
C
Rabert Pinilla
Departamento de Recursos Naturales, Facultad de Ciencias Agronómicas y Forestales, Universidad de la Frontera, PO Box 54-D, Temuco, Chile.
León
L
Bravo Ramírez
D000222:Adaptation, Physiological / Q000502:physiology; D000975:Antioxidants / Q000378:metabolism; D044002:Bryophyta / Q000166:cytology* / Q000235:genetics / Q000502:physiology*; D002241:Carbohydrates / Q000032:analysis; D002734:Chlorophyll / Q000032:analysis / Q000378:metabolism; D003890:Desiccation; D004734:Energy Metabolism / Q000502:physiology; D010940:Plant Proteins / Q000032:analysis / Q000235:genetics; D040901:Proteomics; D014867:Water / Q000032:analysis
D000975:Antioxidants; D002241:Carbohydrates; D010940:Plant Proteins; D014867:Water; D002734:Chlorophyll
Desiccation tolerance; Filmy ferns; Proteomics