Sending algae into space to probe plants in extreme environments

It may sound like the opening scene in a low-budget science fiction movie: Scientists send algae into space—some of it mutant—to see if it will grow. But an Agricultural Research Service scientist and an international team of researchers have in fact sent algae into a low Earth orbit to study the effects of space on photosynthesis and plant growth. The research, funded in part by the European Space Agency, is part of an effort to find new ways to produce food and biofuels in extreme environments.

Autar Mattoo, a plant physiologist with ARS's Sustainable Agricultural Systems Laboratory in Beltsville, Maryland, and his colleagues placed samples of the alga Chlamydomonas reinhardtii in airtight "photo cells" and had them launched in a Russian-made Soyuz space capsule from the Baikonur Cosmodrome in Kazakhstan.

The C. reinhardtii, often studied as a model for photosynthesis, spent 15 days in orbit getting doses of cosmic radiation while under light and temperature conditions that would ensure growth on earth. Four mutants of C. reinhardtii with alterations in an important gene were also sent up. Mattoo and his colleagues from the National Research Council of Italy, based in Rome, and Martin-Luther University in Wittenberg, Germany, exposed the same control and mutant algae to similar conditions in an Earth-based laboratory to compare results.

During photosynthesis in normal conditions, a protein-pigment complex known as "Photosystem II" (PS II) must constantly be repaired to fix damage caused by sunlight and ultraviolet radiation. As part of that repair process, a protein known as "D1" is continuously being replaced. Research has shown that mutations of the D1 protein in the PS II complex can either increase or decrease photosynthetic activity...

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