Sensitivity of Antarctic freshwater algae to salt stress assessed by fast chlorophyll fluorescence transient

Abstract

In this study, we investigated the effects of salt stress (2 mM NaCl) on excitation energy transfer from light harvesting complexes to photosystem II (PS II) in two Antarctic algal species: Klebsormidium sp. and Zygnema sp. Short-term salt stress led to a significant changes in the shape of chlorophyll fluorescence transient (OJIP). Analyses of the polyphasic fluorescence transients (OJIP) showed that the fluorescence yield at the phases J, I and P declined considerably with the time of exposition to salt stress. In both experimental species, OJIP transients reached lowest values of chlorophyll fluorescence signal after 30/60 min. of NaCl exposition. Then, OJIP shape and chlorophyll fluorescence showed species-specific recovery and rised towards original values (about 2/3 of untreated control). Analyses of chlorophyll fluorescence parameters derived from OJIPs showed that salt stress led to a decrease in the maximal efficiency of PS II photochemistry (F V /F M ) in Zygnema sp. but not Klebsormidium sp. The results indicated that the probability of excitation energy transfer before and beyond Q A , and the yield of electron transport beyond Q A is limited by salt-induced stress in Zygnema sp. In addition, salt stress resulted in a decrease in the photosynthetic electron transport per PS II reaction center, but both increase and decrease in the trapping per PS II reaction center was found. Performace index (PI abs ) was affected negatively in Zygnema sp. but possitively Klebsormidium sp. indicating that the latter species was more resistant to salt stress than Zygnema sp.

Molecular and morphological diversity of Zygnema and Zygnemopsis (Zygnematophyceae, Streptophyta) from Svalbard (High Arctic)

“…These polar hydro-terrestrial algal mats are often formed by algae of the genus Zygnema C. Agardh that are very well adapted to the harsh conditions of the polar climate, as demonstrated by various ecophysiological studies (Hawes, 1990; Holzinger et al ., 2009; Pichrtová et al ., 2013, 2014 a , 2014 b ; Vilumbrales et al ., 2013; Choi et al ., 2015). Nevertheless, both floristic and ecophysiological publications refer only to ‘ Zygnema spp.’ because species diversity within these mats remains unexplored.…”

Photosynthetic efficiency, desiccation tolerance and ultrastructure in two phylogenetically distinct strains of alpine Zygnema sp. (Zygnematophyceae, Streptophyta): role of pre-akinete formation

“…The ultrastructure (McLean and Pessoney 1970 , 1971 ; Bakker and Lokhorst 1987 ; Holzinger et al 2009 ; Kaplan et al 2013 ; Pichrtová et al 2013 ) and ecophysiological performance after different stress treatments (Holzinger et al 2009 ; Kaplan et al 2013 ; Vilumbrales et al 2013 ; Pichrtová et al 2014 ) are well described in the genus Zygnema . Holzinger et al ( 2009 ) did not detect significant changes to cellular ultrastructure or photosynthetic performance after experimentally increasing UV to photosynthetic active radiation (PAR) treatment of field-collected arctic strains of Zygnema sp.…”

Gradient of algal and cyanobacterial assemblages in a temporary lake with melting water at Solorina Valley, James Ross Island, Antarctica

“…Skácelová et al 2013). In some selected species, photosynthetic parameters were studied under laboratory conditions in response to light, temperature , and osmotic stress (Vilumbrales et al 2013). However, research on biodiversity is far from being completed because of tens to hundreds of sites that have never been sampled at deglaciated part of James Ross Island.…”