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Abstract Detail

Symbioses: Plant, Animal, and Microbe Interactions

Harris, Steven [1], Kumar, Jyothi [2], Creasey, Erin [2].

The stress biology of extremophile fungi and the nature of fungal interactions with algae.

Extremophiles are broadly recognized as organisms that can live in extreme conditions of temperature, acidity, alkalinity, or salinity. Besides expanding our views on the diversity of life on Earth and perhaps beyond, the study of extremophiles has also provided significant insight into how organisms adapt to stress. Extremophile fungi that primarily colonize exposed rock surfaces, known as “rock inhabiting fungi’ (RIFs), were originally discovered in Antarctica, but have since been found throughout temperate habitats. RIFs possess numerous morphological and physiological adaptations that allow them to thrive in harsh environments that would normally preclude survival. We propose that the “model” black yeast Exophiala dermatitidis can be used to investigate the molecular basis of these adaptations. The accumulation of pigments such as melanin and carotenoids likely play a key role in the stress tolerance of E. dermatitidis. In their functional characterization of the GTPases Cdc42 and Rac1, Guo and Szaniszlo (unpublished results) noted that the absence of Cdc42 resulted in the apparent loss of carotenoids. We have confirmed this and further shown that cdc42 mutants fail to induce the carotenoid biosynthetic gene cluster. We are currently using transcriptome sequencing to better define the role of Cdc42 in pigment synthesis and broader stress responses. We have also discovered that E. dermatitidis can engage in transient mutualisms with photosynthetic algae to support growth and development. This was accomplished by co-culturing E. dermatitidis with the alga Chlorella sorokiniana in the presence of light on a minimal medium that otherwise lacked carbon. Preliminary results show that co-cultivation markedly enhances growth and results in stable associations between fungal and algal cells. Moreover, our results also suggest that algal phytohormones trigger the accumulation of lipid bodies in E. dermatitidis. These results suggest that transient mutualisms may play a significant role in enabling the survival of extremophile fungi in harsh environments.

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1 - University of Nebraska, Center for Plant Science Innovation, E126 Beadle Center, Lincoln, NE, 68588-0660, USA
2 - University of Nebraska, Center for Plant Science Innovation, E131 Beadle Center, Lincoln, NE, 68588-0660, USA

Cdc42 GTPase module.

Presentation Type: Oral Paper:Papers for Topics
Session: 51
Location: Salon 5/The Shaw Conference Centre
Date: Tuesday, July 28th, 2015
Time: 1:30 PM
Number: 51001
Abstract ID:579
Candidate for Awards:None

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