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Water vapor uptake and photosynthesis of lichens: performance differences in species with green and blue-green algae as phycobionts.

Abstract：

:Dry lichen thalli were enclosed in gas exchange chambers and treated with an air stream of high relative humidity (96.5 to near 100%) until water potential equilibrium was reached with the surrounding air (i.e., no further increase of weight through water vapor uptake). They were then sprayed with liquid water. The treatment took place in the dark and was interrupted by short periods of light. CO2 exchange during light and dark respiration was monitored continuously. With no exception water uptake in all of the lichen species with green algae as phycobionts lead to reactivation of the photosynthetic metabolism. Further-more, high rates of CO2 assimilation were attained without the application of liquid water. To date 73 species with different types of Chlorophyceae phycobionts have been tested in this and other studies. In contrast, hydration through high air humidity alone failed to stimulate positive net photosynthesis in any of the lichens with blue-green algae (Cyanobacteria). These required liquid water for CO2 assimilation. So far 33 species have been investigated, and all have behaved similarly. These have included gelatinous as well as heteromerous species, most with Nostoc phycobionts but in addition some with three other Cyanophyceae phycobionts. The same phycobiont performance differences existed even within the same genus (e.g. Lobaria, Peltigera) between species pairs containing green or blue-green phycobionts respectively. Free living algae also seem to behave in a similar manner. Carbon isotope ratios of the lichen thalli suggest that a definite ecological difference exists in water status-dependent photosynthesis of species with green and blue-green phycobionts. The underlying biochemical or biophysical mechanisms are not yet understood. Apparently, a fundamental difference in the structure of the two groups of algae is involved.

journal_name

Oecologia

journal_title

Oecologia

authors

Lange OL,Kilian E,Ziegler H

doi

10.1007/BF00377327

subject

Has Abstract

pub_date

1986-12-01 00:00:00

pages

104-110

issue

eissn

0029-8549

issn

1432-1939

pii

10.1007/BF00377327

journal_volume

pub_type

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Water vapor uptake and photosynthesis of lichens: performance differences in species with green and blue-green algae as phycobionts.