Probing Plants' Pollen Puzzles

By Marcia Wood
August 3, 2004

Those soft, crumbly grains of pollen that make you sneeze are also--as we all learned in grade school--essential for fertilizing flowers. Once fertilized, many of these flowers form foods like plump peaches or crisp apples.

Now, scientists in a team led by Sheila M. McCormick, a plant molecular geneticist with the Agricultural Research Service at Albany, Calif., are discovering more about some little-known aspects of fertilization of our planet's flowering green plants.

In particular, McCormick's team is studying the genes and the products of those genes--proteins--that may be key players in fertilization. That work may enable scientists to alter the activity of genes that today block fertilization of certain wild species with their domesticated cousins. Until such barriers are overcome, the prized genes that the wild relatives harbor cannot, in many cases, be easily moved into their cultivated kin.

The sought-after genes might enable tomorrow's plants to thrive with less fertilizer, less water or perhaps even less pesticide.

Genes cue plants to form proteins called ligands and partner molecules called receptor kinase, which might be essential to fertilization. Signals between these molecules may help the growing pollen tube make its way from the upper part of the flower down to the egg cell at the blossom's base.

In one experiment, McCormick and colleagues used tomato pollen kinases, discovered in their earlier experiments, as the lures or baits for floral ligands. That tactic enabled them to identify many potential new ligands.

Read more about this research in the August issue of Agricultural Research magazine.

McCormick is with the Plant Gene Expression Center, which is staffed by scientists from ARS and the University of California, Berkeley. ARS is the U.S. Department of Agriculture's chief scientific research agency.