Материал из Антэкология /// Anthecology
Distinct short-range ovule signals attract or repel Arabidopsis thaliana pollen tubes in vitro
Background: Pollen tubes deliver sperm after navigating through flower tissues in response to
attractive and repulsive cues. Genetic analyses in maize and Arabidopsis thaliana and cell ablation
studies in Torenia fournieri have shown that the female gametophyte (the 7-celled haploid embryo
sac within an ovule) and surrounding diploid tissues are essential for guiding pollen tubes to ovules.
The variety and inaccessibility of these cells and tissues has made it challenging to characterize the
sources of guidance signals and the dynamic responses they elicit in the pollen tubes.
Results: Here we developed an in vitro assay to study pollen tube guidance to excised A. thaliana
ovules. Using this assay we discerned the temporal and spatial regulation and species-specificity of
late stage guidance signals and characterized the dynamics of pollen tube responses. We established
that unfertilized A. thaliana ovules emit diffusible, developmentally regulated, species-specific
attractants, and demonstrated that ovules penetrated by pollen tubes rapidly release diffusible
pollen tube repellents.
Conclusion: These results demonstrate that in vitro pollen tube guidance to excised A. thaliana
ovules efficiently recapitulates much of in vivo pollen tube behaviour during the final stages of pollen
tube growth. This assay will aid in confirming the roles of candidate guidance molecules, exploring
the phenotypes of A. thaliana pollen tube guidance mutants and characterizing interspecies