Abstract Detail



Ecophysiology

Terlova, Elizaveta [1], Holzinger, Andreas [2], Lewis, Louise [3].

VARIATION IN VEGETATIVE DESICCATION TOLERANCE IN INDEPENDENTLY-EVOLVED DESERT SPECIES OF TETRADESMUS.

Vegetative desiccation tolerance (VDT) — the ability of vegetative cells to recover from extreme loss of protoplasmic water — is a rare but phylogenetically widespread phenomenon. Some VDT species can survive rapid and long-lasting desiccation and recover their physiological activity once water becomes available. Unlike embryophytes, green algae show multiple origins of terrestriality, with algae of desert soil crusts being perhaps the most dramatic example. In Chlorophyta desert species are embedded in aquatic taxa, such as a common freshwater genus Tetradesmus (Sphaeropleales, Chlorophyceae). More importantly, desiccation tolerance in different desert Tetradesmus species has evolved independently from aquatic ancestors, and we expect them to show variation in VDT traits. We demonstrated dramatic differences in response to desiccation of aquatic and desert Tetradesmus using PSII chlorophyll fluorescence as a proxy for the physiological state of cells. When hydrated the quantum yield of photosynthesis was similar for all strains. Likewise, desiccation resulted in a complete loss of photosynthetic capacity. Upon rehydration a clear and significant distinction between aquatic and desert species was apparent: only desert species recovered their photosynthetic activity, the aquatic species remained inactive even after 15 h. The behavior upon rehydration varied among species depending on intensity of desiccation. Rapid desiccation reaching low relative humidity (RH) values (RH ~5% reached in 2‑3 h) appears to cause thestrongestmostdamage. Upon rehydration desert species initially had photosynthetic activity but lost it later. Less severe modes of desiccation (RH ~65% reached in 8 h and RH~85% reached in 12 h) resulted in differences among the independently-evolved desert species. This complex of closely related species of Tetradesmus from different habitats is an ideal system for future investigations of the underlying mechanisms and evolution of desiccation tolerance in chlorophycean algae.


1 - University Of Connecticut, Ecology And Evolutionary Biology, 75 N Eagleville Rd, Storrs, CT, 06269, United States
2 - University of Innsbruck, Institute of Botany, Functional Plant Biology, Sternwartestrasse 15, Innsbruck, 6020, Austria
3 - University Of Connecticut, Department Of Ecology & Evolutionary Biology, 75 North Eagleville Rd, Unit 43, Storrs, CT, 06269, United States

Keywords:
desiccation tolerance
Chlorophyta.

Presentation Type: Poster This poster will be presented at 5:30 pm. The Poster Session runs from 5:30 pm to 7:00 pm. Posters with odd poster numbers are presented at 5:30 pm, and posters with even poster numbers are presented at 6:15 pm.
Number: PPE013
Abstract ID:1022
Candidate for Awards:None


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