Abstract
Chemo-attractants from the ovule have been thought to be key molecules in pollen tube guidance of flowering plants for more than 140 years. However, no molecule has been convincingly demonstrated to be the true attractant that actually controls pollen tube guidance. By using our in vitro Torenia system, we previously showed that the synergid cell emitted some diffusible attractant(s). The attractant molecule was species preferential even in closely relating species, implying that the molecule had rapidly evolved.
We have analyzed ESTs from isolated synergid cells of Torenia fournieri and identified small secreted proteins as candidate pollen tube attractants. To characterize their activity to attract pollen tubes, we tried to purify sufficient amount of recombinant proteins from E. coli and to refold them correctly. We also tried to develop novel in vitro assay to quantitatively analyze the attraction activity. We will demonstrate whether the candidates show the attraction activity or not.
