Auxin, The Morphogen in Plants

The plant hormone auxin is implicated as the morphogen that is responsible for egg production in plants, says the report published in the Science on-line Science Express. Venkatesan Sundaresan, the UC Davis professor of plant biology and plant sciences who led the study highlights the research results as "the plant triggers auxin synthesis at one end of the female reproductive unit called the embryo sac, creating an auxin gradient. The eight nuclei in the sac are then exposed to different levels of auxin, but only the nucleus in the correct position in the gradient becomes an egg cell. And that cell is subsequently fertilized to make the next generation."

This discovery shows that the development of the embryo sac could be the key element in the evolution from gymnosperms (naked seed formers) to flowering plants, the angiosperms. It thus supports the modular theory that the first angiosperms underwent a drastic reduction of the female reproductive unit allowing them to reproduce more efficiently and successfully.

For details, see the press release at: http://www.news.ucdavis.edu/search/news_detail.lasso?id=9142. The abstract is available at: http://www.sciencemag.org/cgi/content/abstract/1167324