Photosynthesis in chlorolichens: the influence of the habitat light regime.
The hypothesis that CO(2) gas exchange and chlorophyll a fluorescence (ChlaF) of lichens vary according to the light regimes of their original habitat, as observed in vascular plants, was tested by analysing the photosynthetic performance of 12 populations of seven dorsoventral, foliose lichens collected from open, south-exposed rocks to densely shaded forests. Light response curves were induced at optimum thallus water content and ChlaF emission curves at the species-specific photon flux at which the quantum yield of CO(2) assimilation is the highest and is saturating the photosynthetic process. Photosynthetic pigments were quantified in crude extracts. The results confirm that the maximum rate of gross photosynthesis is correlated with the chlorophyll content of lichens, which is influenced by light as well as by nitrogen availability. Like leaves, shade tolerant lichens emit more ChlaF than sun-loving ones, whereas the photosynthetic quantum conversion is higher in the latter.
Piccotto
Massimo
M
Dipartimento di Scienze della Vita, Università degli Studi di Trieste, via L. Giorgieri, 10, 34127, Trieste, Italy. mpiccotto@gmail.com
Tretiach
Mauro
M
D000531:Altitude; D002245:Carbon Dioxide / Q000378:metabolism; D002338:Carotenoids / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism*; D000077194:Chlorophyll A; D017753:Ecosystem; D004579:Electron Transport / Q000528:radiation effects; D005453:Fluorescence; D008011:Lichens / Q000502:physiology* / Q000528:radiation effects*; D008027:Light; D009929:Organ Size / Q000528:radiation effects; D010788:Photosynthesis / Q000528:radiation effects*
D002734:Chlorophyll; D002245:Carbon Dioxide; D002338:Carotenoids; C037184:chlorophyll b; D000077194:Chlorophyll A