title: The desert moss Pterygoneurum lamellatum (Pottiaceae) exhibits an inducible ecological strategy of desiccation tolerance: effects of rate of drying on shoot damage and regeneration.
abstract: OBJECTIVE
  Bryophytes include clades that incorporate constitutive desiccation tolerance, especially terrestrial species. Here we test the hypothesis that the opposing ecological strategy of desiccation tolerance, inducibility, is present in a desert moss, and address this hypothesis by varying rates of drying in a laboratory study. Desiccation tolerance is arguably the most important evolutionary innovation relevant to the colonization of land by plants; increased understanding of the ecological drivers of this trait will eventually illuminate the responsible mechanisms and ultimately open doors to the potential for the application of this trait in cultivated plants.
  
  
  METHODS
  Plants were cloned, grown in continuous culture (dehardened) for several months, and subjected to rates of drying (drying times) ranging from 30 min to 53 h, rehydrated and tested for recovery using chlorophyll fluorescence, leaf damage, and regeneration of protonema and shoots.
  
  
  RESULTS
  Rate of drying significantly affected all recovery responses, with very rapid drying rates severely damaging the entire shoot except the shoot apex and resulting in slower growth rates, fewer regenerative shoots produced, and a compromised photosynthetic system as inferred from fluorescence parameters.
  
  
  CONCLUSIONS
  For the first time, a desert moss is shown to exhibit an ecological strategy of desiccation tolerance that is inducible, challenging the assumption that arid-land bryophytes rely exclusively on constitutive protection. Results indicate that previous considerations defining a slow-dry event in bryophytes need reevaluation, and that the ecological strategy of inducible desiccation tolerance is probably more common than currently understood among terrestrial bryophytes.
authors.affiliation: School of Life Sciences, University of Nevada, 4505 Maryland Parkway, Las Vegas, Nevada 89154-4004, USA. LRS@UNLV.nevada.edu
authors.forename: Lloyd R
authors.initials: LR
authors.lastname: Stark
authors.forename: Joshua L
authors.initials: JL
authors.lastname: Greenwood
authors.forename: John C
authors.initials: JC
authors.lastname: Brinda
authors.forename: Melvin J
authors.initials: MJ
authors.lastname: Oliver
mesh_terms: D000222:Adaptation, Physiological; D019068:Bryopsida / Q000502:physiology*; D002734:Chlorophyll / Q000378:metabolism; D003890:Desiccation; D005453:Fluorescence; D006813:Humidity; D018515:Plant Leaves / Q000502:physiology; D018520:Plant Shoots / Q000502:physiology*; D012038:Regeneration; D013997:Time Factors; D014867:Water / Q000032:analysis / Q000378:metabolism
chemical_list: D014867:Water; D002734:Chlorophyll
keywords: Chlorophyll fluorescence; chlorosis; protonema; rapid-dry; regeneration; slow-dry