Times are displayed in (UTC-05:00) Central Time (US & Canada) Change

Pigment-Related Defense in Temperate Lichens: Landlines in Exobiology

Session: New Voices in Geobiology

Presenting Author:

Ronan Fast

Authors:

Fast, Ronan¹, Fulton, James², Athar, Tabinda³, Kirpal, Meera⁴, Ford, Josh⁵

(1) Geosciences, Baylor Universtiy, Waco, TX, USA, (2) Geosciences, Baylor University, Waco, TX, USA, (3) Geosciences, Baylor University, Waci, TX, USA, (4) Geosciences, Baylor University, Waco, TX, USA, (5) Geosciences, Baylor University, Waco, TX, USA,

Abstract:

Despite a deceptively simple appearance, lichens are succession pioneers that develop from a complex mutualism between fungi and phototrophic microbes. Lichens produce secondary metabolites that respond to a myriad of stressors. These products include numerous pigment compounds, which are considered potential biosignatures due to their ubiquity in the biosphere and their functionals roles in light exposure. In this study, we analyze and compare pigments that are produced in lichen cortices, namely the anthraquinone parietin, the depsidone atranorin, and scytonemin - each of which exhibit UV-screening behavior. We hypothesize that exposure to long wavelength UVA (black light) stress stimulates production of these photoprotective UV-screening pigments. These pigments also have antioxidant properties, and we hypothesize exposure to salt stress will similarly affect pigments. Our lichen samples include foliose grey-blue species of the genus Physcia and orange Xanthoria, which often cohabitate in temperate conditions alongside dark patches of non-lichenized cyanobacteria. We aim to induce pigment production by incubating samples of lichenized bark under black light and increased salinity, with the goal of evaluating the importance of these protective compounds in lichen environmental resistance, particularly in species taken from a temperate environment. The pigments are extracted thrice over a one month period via acetone wash, then characterized through HPLC/LC-MS with comparison to chemical standards. Our checkpoints for extraction include T0, our control, T2, the midpoint, and TF, the concluding extraction. We will contrast pigment levels in each of four experimental conditions to determine lichen response to altered stress environments, and discuss possible applications to modeling exobiology.