Wieners, Paul Christian , Göthlich, Lena and Bilger, Wolfgang (2019) The influence of Zn and I on growth and desiccation-induced chlorophyll fluorescence quenching of Trebouxia asymmetrica. Environmental and Experimental Botany, 162 . pp. 496-503. DOI 10.1016/j.envexpbot.2019.03.025.

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Abstract

The composition of the growth medium has a major influence on the physiological properties of microalgae. We have previously shown that addition of the trace elements Zn and I enhances desiccation-induced fluorescence quenching (q des ) in the lichen phycobiont Trebouxia asymmetrica. q des is likely to be an important factor of the tolerance against drought, as it has a protective function against photoinhibition in the dehydrated state of this poikilohydric organism. The influence of the presence of iodine and/or zinc ions in culture media on growth of T. asymmetrica and its ability to show q des were investigated. T. asymmetrica was able to grow in seawater and showed enhanced q des as compared to when grown in the usual Bold's basal growth medium. While artificial seawater had no effect, addition of Zn and I in the concentrations present in natural seawater enhanced q des to almost the same level as observed in natural seawater. The presence of Zn and I also increased growth by the factor of almost 2, thus approximating the growth rate reached in enriched seawater. Both effects, enhancement of q des and of the growth rate were dependent on the simultaneous presence of both elements. Adding only one element at any concentration resulted in no or very little effect on either growth rate or q des . The mechanism of the action of both elements is unknown. It is possible that the simultaneous presence of I and Zn has a profound effect on the fitness of lichens containing T. asymmetrica in nature.

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