Female flowers 'communicate' whether to accept or reject male pollen grains

Washington, Oct 24 : In a new study, University of Missouri researchers have found that flowers use specific pollen proteins to 'communicate' whether they would accept or reject the pollen grains, required for fertilisation.

When pollen grains arrive, the pollen (the male part of the flower) 'communicates' with the pistil (the female part of the flower), where molecules take the place of words and allow the pollen to identify itself to the pistil.

Insights into this 'communication' may pave the way for methods to control the spread of transgenes from genetically-modified crops to wild relatives, offer better ways to control fertilization between cross species, and lead to a more efficient way of growing fruit trees.

"Unlike an animal's visual cues about mate selection, a plant's mate recognition takes place on a molecular level. The pollen must, in some way, announce to the pistil its identity, and the pistil must interpret this identity. To do this, proteins from the pollen and proteins from the pistil interact; this determines the acceptance or rejection of individual pollen grains," said Bruce McClure, associate director of the Christopher S. Bond Life Sciences Center and researcher in the MU Interdisciplinary Plant Group and Division of Biochemistry.

For the study, the researchers used two specific pistil proteins, NaTTS and 120K, as sample to see what pollen proteins would bind to them. The researchers chose the above pistil proteins because they directly influence the growth of pollen down the pistil to the ovary where fertilization takes place.

The team observed that three proteins, S-RNase-binding protein (SBP1), the protein NaPCCP and an enzyme, bound to the pistil proteins.

The above action made the researchers to believe that these proteins may contribute to the signalling processes that affect the success of pollen growth.

"Our experiment was like putting one side of a Velcro strip on two pistil proteins and then screening a collection of pollen proteins to see which of the pollen proteins have the complementary Velcro strip for binding. If it sticks, it's a good indication that the pollen proteins work with the pistil proteins to determine the success of reproduction," said McClure.

In their study, the researchers used Nicotiana alata, a relative of tobacco commonly grown in home gardens as "flowering tobacco."

The study, "Pollen Proteins Bind to the C-Terminal Domain of Nicotiana Alata Pistil Arabinogalactan Proteins," was published in the Journal of Biological Chemistry.

ANI