| Summary: | <p>Abstract</p> <p>Background</p> <p>Pollen tubes deliver sperm after navigating through flower tissues in response to attractive and repulsive cues. Genetic analyses in maize and <it>Arabidopsis thaliana </it>and cell ablation studies in <it>Torenia fournieri </it>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.</p> <p>Results</p> <p>Here we developed an <it>in vitro </it>assay to study pollen tube guidance to excised <it>A. thaliana </it>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 <it>A. thaliana </it>ovules emit diffusible, developmentally regulated, species-specific attractants, and demonstrated that ovules penetrated by pollen tubes rapidly release diffusible pollen tube repellents.</p> <p>Conclusion</p> <p>These results demonstrate that <it>in vitro </it>pollen tube guidance to excised <it>A. thaliana </it>ovules efficiently recapitulates much of <it>in vivo </it>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 <it>A. thaliana </it>pollen tube guidance mutants and characterizing interspecies pollination interactions.</p>
|
|---|
