Live-Cell Study of Pollen Tube Guidance

Research Seminar
Title: Live-Cell Study of Pollen Tube Guidance
Speaker: Tetsuya Higashiyama，Ph.D.
Vice Director, Professor
Institute of Transformative Bio-Molecules (WPI-ITbM),
Nagoya University
Time: 13:00-14:30, Oct. 13, 2017
Location: Youcai Deng Hall，School of Life Sciences（生科院邓祐才报告厅）
Host：Lijia Qu
Abstract：
Pollen tube guidance for successful reproduction of flowering plants involves complex cell-to-cell communication. Defensin-like peptide LUREs are pollen tube attractants of Torenia and Arabidopsis secreted by two egg-accompanying “synergid cells” (Science 2001; Nature 2009; PLoS Biol. 2012). To understand the molecular mechanism of pollen tube guidance, we have been taking two approaches of live-cell study (for reviews, Cell Growth Differ. 2013; Annu. Rev. Plant Biol. 2015). The first approach is to use precisely defined semi-in vitro system (semi-in vivo system), including development of various microfluidics devices (e.g., RSC Adv. 2013). Semi-in vitro studies combined with synthetic chemistry lead to discovery of novel intercellular signaling molecules involved in pollen tube guidance. Arabinogalactan sugar chain AMOR derived from Torenia ovular sporophytic tissues is critical to make pollen tubes competent before attraction by TfLUREs (Curr. Biol. 2016; Plant Physiol. 2017). PRK6 is a receptor kinase of Arabidopsis, which is critical in sensing of AtLURE1 peptides (Nature 2016). Cocrystal structure analysis of AtLURE1 and PRK6 suggested unique action mechanism of AtLURE1 (Nat. Commun. 2017). Development of fluorescent small molecules is also in progress for single molecule or super-resolution imaging of cellular signaling (e.g., J. Am. Chem. Soc. 2017). The second approach is based on in vivo imaging. We have shown that pollen tube guidance is intimately related with double fertilization (e.g., Dev. Cell 2013; Cell 2015). By using two-photon microscopy, we have succeeded in visualizing pollen tube guidance in the pistil tissue (e.g., Development 2015, Protoplasma 2015). In this talk, I will talk about recent progresses of our pollen tube guidance study to discuss how pollen tubes are navigated to ovules, focusing on precise directional control, species-specific attraction, and one-to-one relationship between multiple ovules and pollen tubes.
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