Plants Screen Potential Mates

by Brian Thomas, M.S. *

Almost all behavioral experts would agree that good communication is key to the survival of a healthy relationship. This principle also holds true in the plant world.

When a sperm-containing pollen grain lands on the stigma of a flower’s egg-containing pistil, a molecular communication process begins that filters out incorrect or undesirable potential mates. Researcher Bruce McClure of the University of Missouri discovered what are probably the specific pollen proteins used by a relative of the tobacco plant in this necessary biochemical exchange. “The pollen must, in some way, announce to the pistil its identity, and the pistil must interpret this identity,” he said in a university press release¹ concerning the study that appeared in an October 2008 issue of the Journal of Biological Chemistry.²

Not only does the molecular interaction “weed out” pollen grains of unrelated species, but McClure discovered that this remarkable process also excludes pollen grains that are too closely related! “Plants must rely on the interaction of molecules to determine appropriate mating partners and avoid inbreeding.”¹ Like animals, inbred plants are more susceptible to loss of genomic integrity, disease, and death.

These flowering plants have a well-designed communication system that works to maintain species integrity. By it, they help preserve their own identity as a “kind” by excluding pollen grains that may blow in from the wrong plants. Not only that, they also protect the integrity of the next generation by rejecting pollen that would preserve too many mutations. If these (and probably other) plants did not have this conservation system, they might not have persisted until today.

How could Darwinian evolution, which requires the accumulation of mutations, be responsible for producing plants that are evidently programmed to prevent mutation? This intricate biochemical system helps guard the plant from too much change—and therefore, from the supposed forces of evolution. Even plants have been given capacities to preserve their integrity, which increases their survivability. This is exactly what would be expected from plants that have each been created to reproduce “after his kind.”³

References

1. Female Plant 'Communicates' Rejection or Acceptance of Male. University of Missouri press release, October 23, 2008.
2. Lee, C. B., K. N. Swatek and B. McClure. 2008. Pollen Proteins Bind to the C-terminal Domain of Nicotiana alata Pistil Arabinogalactan Proteins. Journal of Biological Chemistry. 283 (40): 26965-26973.
3. Genesis 1:11-12.

* Mr. Thomas is Science Writer.

Article posted on November 4, 2008.