Tetsuya Higashiyama

Whither molecules for overcoming genome barriers?

Tetsuya Higashiyama

The fertilization process in flowering plants is a dynamic process that occurs deep within the pistil. Dynamics and molecular mechanisms of plant reproduction have been in mystery because it is difficult to capture the actual process in real time in living tissues. I have been working on live-cell analysis of plant reproduction with an emphasis on technological development. In 2009, we succeeded in identifying the pollen tube attractant "LURE peptide", which had been searched for more than 140 years. Since then, we have been taking interdisciplinary approaches including live-cell imaging, single cell-type transcriptome, engineering, and synthetic chemistry, which were promoted by directing big grant-projects (ERATO, WPI (to launch ITbM, a new interdisciplinary institute of Nagoya University for chemistry and biology), and JSPS Grant-in-Aid for Scientific Research on Innovative Areas “The Birth of New Plant Species”).

 For example, the receptor for Arabidopsis LURE1, PRK6, was identified by micromanipulation screen for mutant pollen tubes and by cocrystal structure analysis (Nature, 2016; Nat. Commun., 2017). Interestingly PRK6 was also involved in pollen tube growth with other PRKs. PRK6 changed localization toward LURE peptide, whereby growth direction was reoriented. To understand how PRK6 changes localization, we have been preparing for super-resolution and single-molecule imaging, including 1) various microfluidics for pollen tube imaging (e.g., RSC Adv., 2013; Biomicrofluidics, 2018; RSC Adv., 2021), and 2) super-photostable fluorescent dyes (e.g., Angew. Chem. Int. Ed., 2015). I also launched a new research grant CREST “Membrane Trafficking Dynamics Driving Chemotropism” (2020-2026), as inspired by our collaboration on adaptor proteins for endocytosis of receptor proteins of the pollen tube (Commun. Biol., 2018). Physicists are also involved in this project to develop a new microscope to observe dynamics of all vesicles in growing pollen tube tips.

 In recent years, we have been focusing on molecules for overcoming species barriers, which was specially promoted by collaborations in ITbM and The Birth of New Plant Species project. As the final talk as a PI of ITbM, I will summarize achievements and insights from these projects and will talk about future directions.