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How flowering plants precision engineer their pollination

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"Flowers make certain that gamete fusion has successfully occurred before other pollen are repelled."/Mike Cohea, Brown University

From “Pollination With Precision: How Flowers Do It” (ScienceDaily, May 17, 2012), we learn

Pollination could be a chaotic disaster. With hundreds of pollen grains growing long tubes to ovules to deliver their sperm to female gametes, how can a flower ensure that exactly two fertile sperm reach every ovule? In a new study, Brown University biologists report the discovery of how plants optimize the distribution of pollen for successful reproduction.

In pollination, hundreds of sperm-carrying pollen grains stick to the stigma suspended in the middle of a flower and quickly grow a tube down a long shaft called a style toward clusters of ovules, which hold two female sex cells. This could be a chaotic frenzy, but for the plant to succeed, exactly two fertile sperm should reach the two cells in each ovule — no more, no less. No ovule should be left out, either because too many tubes have gone elsewhere, or because the delivered sperm don’t work.

In the journal Current Biology, Brown University biologists report that flowers have evolved an elegant safeguard system to ensure that only the minimum necessary number of pollen tubes will reach each ovule.

“There is a mechanism that prevents too many pollen tubes from delivering too many sperm,” said Mark Johnson, associate professor of biology at Brown and senior author on a new paper detailing the discovery. “But the other cool thing is that there is also a way to salvage fertilization if the first father is a dud.”

The critical question isn’t how this degree of precision could be achieved – in flowering plants, known only from the Mesozoic era to today (if that long), but how it could have been achieved without intelligent guidance during such a period.

As long as Darwinism is not forced to submit to reality-based calculations of probability, there will be no shortage of fanciful ideas getting in the way of serious inquiry.

Incidentally, Despite a concerted effort by evolutionary developmental (evo-devo) biologists and paleontologists the origin of angiosperms remains enigmatic and mysterious (Frohlich and Chase 2007). Further, certain paleobotanists regard the problem of flowering plant origins, “as intractable a mystery today as it was to Darwin 130 years ago” (page 318, Rothwell et al. 2009).


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