Photosynthetic performance of different genotypes of the green alga Klebsormidium sp. (Streptophyta) isolated from biological soil crusts of the Alps
Karsten, Ulf; Pröschold, Thomas; Mikhailyuk, Tatiana; Holzinger, Andreas
Members of the cosmopolitan green algal genus Klebsormidium (Klebsormidiales, Streptophyta) are typical components of biological soil crusts, which exert many important ecological functions. In the present study four different Klebsormidium genotypes according to the clades of Rindi et al. (2011) were isolated from alpine soil crusts in the Tyrolean Alps, Austria between 649 and 2435 m a.s.l. The photophysiological performance was investigated under increasing photon fluence rates using an oxygen optode. Although isolate-specific response patterns could be documented, the differences were rather small. All data clearly indicated very low light requirements in the four Klebsormidium strains as reflected in low light compensation as well as in low light saturation points. In spite of these rather shade acclimation, no indication of photoinhibition was observed in 3 out of 4 isolates, at least up to the maximum applied photon fluence rate of 500 μmol photons PAR m–2 s–1. The remaining strain exhibited a small decrease in maximum oxygen development under the highest photon fluence rate tested. Dark respiration was measured directly before and after the application of the different light levels, and all Klebsormidium isolates showed strongly enhanced rates after treatment with the highest photon fluence rate. Although the photophysiological data showed some differences, the response patterns in the four different genotypes of Klebsormidium were relatively similar, which well explains the widespread abundance of members of this genus in biological soil crusts of the alpine regions of the Tyrolean Alps.