Ecophysiology & Structure: Epiphytic versus Crustose Lichens of the Atacama Fog Desert

Abstract

Cryptogamic species such as lichens are almost undescribed from the hyperarid Atacama Desert in Chile where fog water deposition and dewfall are their single water sources. We elucidated the photosynthetic activity paterns of crustose and epiphytic chlorolichens depending on different water sources (high relative air humidity vs. liquid water). Besides gas exchange measurements (GFS), photobiont sequencing (ITS1/ITS2) and confocal laser scanning microscopy (CLSM) was applied to understand their structure and ecophysiology.

Full text

Ecophysiology & Structure:
Epiphytic versus Crustose Lichens of the Atacama Fog Desert
Patrick Jung1, Lena Weber1, Lukas Lehnert2, Philippe Clerc3, Claudia Colesie1, Burkhard Büdel1
1TU Kaiserslautern, 2Philipps-University Marburg, 3 CJB, Genéve, corresponding author: patrick_jung90@web.de
The Atacama desert in Chile is one of the driest and probably oldest deserts on Earth. To survive in these conditions
life must adapt to very low water availability due to the almost complete absence of rain and high solar radiation.
Only a few extremophile organisms are able to conquer this habitat with different strategies.
How are photobiont orientation and structural features of the thallus
influencing the photosynthetic activity of the chlorolichens?
Can crustose (Acarospora cf. socialis & Caloplaca sp.) and epiphytic
chlorolichens (Pseudevernia sp. & Ramalina peruviana) reach a positive
net photosynthesis based on high relative air humidity?
Structural Analysis
Confocal laser scanning
microscopy
Light microscopy
Photosynthetic Performance
CO2 gas exchange measurements
Saturation by high relative air humidity
Water dependent photosynthetic response at 17°C
Hyperspectral reflectance measurements
Photobiont Sequencing
DNA extraction
PCR (ITS1/ITS2)
Sequencing
NCBI blast
Epiphytic Lichens: Activation by high relative air
humidity. Water captured out from fog is assumed to be
the predominant water source. Loose fungal medulla
and a centered air cavity optimize gas exchange of the
aggregated photobiont. In comparison, positive net
photosynthesis is increased by more than 10x, which is
also visible in the hyperspectral chlorophyll signal.
Crustose Lichens + Substrate: No positive net
photosynthesis by high relative air humidity. The
predominant water source is expected to be morning
dew, linked to short activity periods. Higher photobiont/
fungus ratio + densely packed algal layers, protected from
solar radiation, are strategies to promote photosynthesis.
Hyperspectral chlorophyll signal and CO2uptake are low.
Introduction
Methods
Results
Discussion
Plant Ecology
& Systematics
Can hyperspectral remote sensing data be used as a proxy for
photosynthetic activity?
Epiphytic Chlorolichens Crustose Chlorolichens + Substrate
Chlorophyll
Water
Chlorophyll
Water
Chlorophyll
Water
Chlorophyll
Water
BLAST
similarity
photobiont:
98%
Uncultured
Trebouxia
(Accession#:
AJ969582.1)
BLAST
similarity
photobiont:
98%
Trebouxia
arboricola
(Accession#:
Z795381.1)
BLAST
similarity
photobiont:
99%
Trebouxia
asymmetrica
(Accession#:
Z95380.1)
BLAST
similarity
photobiont:
98%
Trebouxia
impressa
(Accession#:
Z95383.1)