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Plant evolves a new function? Or was it designed?

plant enzyme has day/night forms/G. L. Kohuth

From “Botany: Moonlighting Enzyme Works Double Shift 24/7” (ScienceDaily, Jan. 31, 2012), we learn ,

A team of researchers led by Michigan State University has discovered an overachieving plant enzyme that works both the day and night shifts.

The discovery, featured in the current issue of Proceedings of the National Academies of Science, shows that plants evolved a new function for this enzyme by changing merely one of its protein building blocks.

Evolved a new function?

In arabadopsis, the much-studied mustard plant, the enzyme ATP synthase plays a daytime role in storing energy from photosynthesis. At night, it transports energy to the roots. One of the enzyme’s components has two forms, one filling each function:

The building block on which the researchers focused is called gamma, a component of ATP synthase. There are two forms of gamma, gamma-1 and gamma-2. When researchers removed gamma-1, photosynthesis was completely stopped. When gamma-2 was removed, the plant could not make normal root hairs (the part of the root that takes up nutrients.)

Some friends’ baloney meters shorted out, and they asked, what does “evolved a new function” mean here?

The concept of evolution is time-dependent. The parent function precedes the daughter function. Which is which? Energy is produced before it is stored – but it must be stored when it is produced. One friend remarked, “I see no ‘evolution’ here. The more sensible inference is that this enzyme’s dual role was designed that way.”

One way of putting it: The plant enzyme “was evolved” to do both functions at once.

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3 Responses to Plant evolves a new function? Or was it designed?

  1. Just for clarification, ancestral enzymes (from other plant species, and even single celled organisms that obviously don’t have roots to traffic energy to) don’t have the transport function.

    It is divergence in this enzyme (following an ancient gene duplication), respective to the ancestral that grants it this function.

    “The more sensible inference is that this enzyme’s dual role was designed that way.”

    An inference drawn on what? Seems like a theistic evolution-”God did it that way” bit of hand-waving to me. Which is fine, but totally outside of, and superfluous to the science.

  2. What is your inference drawn on?

    Seems like bogus magic- “It just happened” bit of handwaving to me- TOTALLY outside of science…

  3. The authors drew their inference when detailed phylogenetic analysis of plant genomes demonstrated gene duplication(s) with divergence to this new function.

    Unicellular plants don’t have non-photosynthetic bits like roots. So News’ question: “The concept of evolution is time-dependent. The parent function precedes the daughter function. Which is which? Energy is produced before it is stored”

    Appears to be answered. The ancestral form is energy producing. The duplicated and diverged form acquired additional roles.

    What is your inference that both roles were designed at the same time drawn upon?

    I’d wager your response will be some rant about genomics and phylogenetics.

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