News & Announcements

(August '09)

 

In collaboration with Dr. Mark Johnson, Brown University, we wrote a peer-reviewed research article that identified for the first time the transcriptome of in vivo-grown pollen tubes. This work has now been published as a research article in PLoS Genetics.

In addition, an illustration from this study (above) was used as the featured image (cover art) of the issue in which this article was published. (Link to cover art). The following summary accompanied the cover art:

In flowering plants, pollen tubes germinate on the stigma surface and extend through the pistil to locate and deliver sperm to female gametes. An article in this issue of PLoS Genetics (see Qin et al, 10.1371/journal.pgen.1000621) uses bundles of pistil-grown pollen tubes, similar to those shown here, to define genome-wide changes in Arabidopsis pollen tube gene expression that occur in response to growth through pistil tissue. Dramatic changes in gene expression occur in pistil-grown tubes and point to genes that are required for the ability of pollen tubes to grow and reach their cellular targets.

Reference:

Qin Y., Leydon A. R.,, Manziello A., Pandey R., Mount D., Denic S., Vasic B., Johnson M. A. and Palanivelu, R. (2009).

Penetration of the Stigma and Style Elicits a Novel Transcriptome in Pollen Tubes, Pointing to Genes Critical for Growth in a Pistil. PLoS Genet 5(8): e1000621.

Link to article or access the pdf file.

Abstract of research article:

Pollen tubes extend through pistil tissues and are guided to ovules where they release sperm for fertilization. Although pollen tubes can germinate and elongate in a synthetic medium, their trajectory is random and their growth rates are slower compared to growth in pistil tissues. Furthermore, interaction with the pistil renders pollen tubes competent to respond to guidance cues secreted by specialized cells within the ovule. The molecular basis for this potentiation of the pollen tube by the pistil remains uncharacterized. Using microarray analysis in Arabidopsis, we show that pollen tubes that have grown through stigma and style tissues of a pistil have a distinct gene expression profile and express a substantially larger fraction of the Arabidopsis genome than pollen grains or pollen tubes grown in vitro. Genes involved in signal transduction, transcription, and pollen tube growth are overrepresented in the subset of the Arabidopsis genome that is enriched in pistil-interacted pollen tubes, suggesting the possibility of a regulatory network that orchestrates gene expression as pollen tubes migrate through the pistil. Reverse genetic analysis of genes induced during pollen tube growth identified seven that had not previously been implicated in pollen tube growth. Two genes are required for pollen tube navigation through the pistil, and five genes are required for optimal pollen tube elongation in vitro. Our studies form the foundation for functional genomic analysis of the interactions between the pollen tube and the pistil, which is an excellent system for elucidation of novel modes of cell–cell interaction.

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