Planta

, Volume 231, Issue 1, pp 195–208

Dehydration rate and time of desiccation affect recovery of the lichenic algae Trebouxia erici: alternative and classical protective mechanisms

  • Francisco Gasulla
  • Pedro Gómez de Nova
  • Alberto Esteban-Carrasco
  • José M. Zapata
  • Eva Barreno
  • Alfredo Guéra
Original Article

Abstract

The mechanisms involved in desiccation tolerance of lichens and their photobionts are still poorly understood. To better understand these mechanisms we have studied dehydration rate and desiccation time in Trebouxia, the most abundant chlorophytic photobiont in lichen. Our findings indicate that the drying rate has a profound effect on the recovery of photosynthetic activity of algae after rehydration, greater than the effects of desiccation duration. The basal fluorescence (Fo) values in desiccated algae were significantly higher after rapid dehydration, than after slow dehydration, suggesting higher levels of light energy dissipation in slow-dried algae. Higher values of PSII electron transport were recovered after rehydration of slow-dried Trebouxia erici compared to rapid-dried algae. The main component of non-photochemical quenching after slow dehydration was energy dependent (qE), whereas after fast dehydration it was photoinhibition (qI). Although qE seems to play a role during desiccation recovery, no significant variations were detected in the xanthophyll cycle components. Desiccation did not affect PSI functionality. Classical antioxidant activities like superoxide dismutase or peroxidase decreased during desiccation and early recovery. Dehydrins were detected in the lichen-forming algae T. erici and were constitutively expressed. There is probably a minimal period required to develop strategies which will facilitate transition to the desiccated state in this algae. In this process, the xanthophyll cycle and classical antioxidant mechanisms play a very limited role, if any. However, our results indicate that there is an alternative mechanism of light energy dissipation during desiccation, where activation is dependent on a sufficiently slow dehydration rate.

Keywords

Algae Antioxidants Dehydrin Desiccation Non-photochemical quenching Trebouxia Xanthophyll 

Abbreviations

Fo

Minimal fluorescence intensity in dark-adapted samples

Fm

Maximal fluorescence intensity in dark-adapted samples

Fv

Variable fluorescence (Fv = Fm − Fo)

FV/Fm

Maximal quantum yield of PSII photochemistry

Fm

Maximum fluorescence intensity in illuminated samples

Fo

Minimum fluorescence intensity in illuminated samples state

Fs

Fluorescence intensity during exposure to light

Fv/Fm

Maximum quantum yield of PSII in light-adapted samples

ϕPSII

Quantum yield of PSII during exposure to light

qP

Photochemical quenching

qN

Non-photochemical quenching

qE

Energy-dependent quenching

qI

Photoinhibitory quenching

qM

Middle phase of dark relaxation quenching

A

Antheraxantin

DPS

De-epoxidation state of the xanthophyll cycle

PAR

Photosynthetically active radiation

P700

Reaction centre of the PSI

PSI, PSII

Photosystem I (II)

POX

Peroxidase

RD

Rapid dehydration

RWC

Relative water content

SD

Slow dehydration

SOD

Superoxide dismutase

V

Violaxanthin

Z

Zeaxanthin

Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  • Francisco Gasulla
    • 1
  • Pedro Gómez de Nova
    • 1
  • Alberto Esteban-Carrasco
    • 2
  • José M. Zapata
    • 2
  • Eva Barreno
    • 1
  • Alfredo Guéra
    • 2
  1. 1.Dpto. de Botánica, Fac. de Biología, Instituto Cavanilles de Biodiversidad y Biología EvolutivaUniversitat de ValènciaBurjassotSpain
  2. 2.Dpto. de Biología Vegetal, Fac. de BiologíaUniversidad de AlcaláAlcalá de Henares, MadridSpain

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