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posted by Fnord666 on Sunday November 11 2018, @05:33PM   Printer-friendly
from the I-thought-C4-went-boom dept.

Submitted via IRC for Bytram

Dry conditions may have helped a new type of plant gain a foothold on Earth

Researchers have long believed that falling carbon dioxide levels drove the origin of plants with this innovation, but a new study in the Proceedings of the National Academy of Sciences, based on biochemical modeling by a group led by University of Pennsylvania biologists and paleoclimate modeling by a group at Purdue University, indicates that water availability may have been the critical factor behind the emergence of C4 plants.

"The initial origin of C4, which happened when atmospheric carbon dioxide was still very high, seems driven by water limitation," says Haoran Zhou, a graduate student in the School of Arts and Sciences' Biology Department and first author on the paper. "Then later, about 5 to 8 million years ago, there's a large expansion of C4 grasslands. That's because carbon dioxide was getting lower and lower. Carbon dioxide and light intensity were actually the limiting factors favoring C4 at that time."

"What we show," says Erol Akçay, an assistant professor of biology at Penn, "is that the increased water efficiency of the C4 pathway is enough to give it an initial ecological advantage in relatively arid environments. That's the benefit of doing this type of physiological modeling. If you were only looking at temperature and carbon dioxide, you might miss this role of water and light."

The researchers' work also suggest that C4 plants may have had a competitive advantage over C3 plants even when carbon dioxide levels in the atmosphere were still relatively high, in the late Oligocene.

"The inference is that C4 could have evolved quite a bit earlier than we previously thought," says Penn's Brent Helliker, an associate professor of biology who, along with Akçay, serves as Zhou's advisor. "This supports some molecular clock estimates for when C4 evolved as well."


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  • (Score: 3, Informative) by Fluffeh on Sunday November 11 2018, @08:56PM

    by Fluffeh (954) on Sunday November 11 2018, @08:56PM (#760710) Journal

    From the first section of the article:

    This same period saw the emergence of a new form of photosynthesis in a subset of plants, the C4 pathway. Present in a subset of plants, the C4 pathway supplemented the earlier C3 photosynthetic pathway, meaning those species now reaped energy from the sun using two different strategies.

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