Transcriptome analysis of the Arabidopsis semi-In vivo pollen tube guidance system uncovers a distinct gene expression profile

In flowering plants, pollen tube guidance is an enigmatic process involving multiple cell-to-cell communications. Several important signal molecules associated with this process have been previously identified, such as LUREs, which are pollen tube attractants derived from Torenia fournieri synergid cells. To identify pollen tube receptors of ovule-secreted attractant signals, we constructed an Arabidopsis semi-in vivo pollen tube guidance system and used microarray analysis to characterize the specific transcriptome. A distinct gene expression profile was observed for pollen tubes that had grown through stigma and style tissues of a pistil and communicated with ovules. Genes involved in signal transduction, transcription, and pollen tube growth were overrepresented, with many genes newly detected as expressed in pollen tubes. The roles of some candidate receptor-like kinase genes in micropylar pollen tube guidance were revealed by reverse genetics analysis. Our results provide valuable clues for research on cell-to-cell interactions during fertilization.