Masaaki K. Watahiki

How to Visualize Invisible Auxin Response

Masaaki K. Watahiki , Associate Professor

Faculty of Science, Graduate School of Life Science Department of Biological Sciences, School of Science (Biology)

High school : Kitami Hokuto High School (Hokkaido)

Academic background : Graduate School of Environment Earth Science, Hokkaido University

Research areas
Plant Physiology, Plant Morphology
Research keywords
Plant Physiology, Plant Hormone, Auxin, Gene Expression, Luciferase

Why Do You Study?

Science is an interpretation of incomprehensible phenomena in understandable principles. As a biologist, I am always looking at living organisms for research purposes. However, just looking alone is not enough to understand the principles intrinsic in the organism. Before discussing this further, I would like to explain a little bit about my background.

     When I was ten years old, I contracted a serious illness, rheumatic fever for approximately three years. Occasionally my physical condition would get better, and I was allowed to read comics, picture books of plants, insects and fungi, as well as an encyclopedia (a kind of hard copy of the Wikipedia website) in bed and I imagined myself playing outside. Although that encyclopedia was issued more than forty years ago, its hand written figures and ideas were easy to understand. Fortunately, I fully recovered from the illness and I was able to play outdoors again. At that time, I was completely absorbed in the microscopic world which is made up of invisible tiny things only seen using a microscope. Although the shape of larger living organisms can be clearly seen, I was amazed and impressed at the complexity of plant cells or plankton which could be seen only through a microscope. This feeling of wonder was a totally different experience from reading an encyclopedia. After that, I wanted to record pictures of cells and tissues and tried doing microscope photography with a film camera. I could not take good pictures in the beginning but with this experience, I realized that microscope photography required a special setup. I was able to record pictures afterward, but a question arose, "Why are they (tissues, cells and living organisms) shaped like this in here?"

     There should be two answers for this question: one that explains the process how they were made and the other that explains the reason why such a shape (process) is necessary. I am conducting research in order to answer this question.


What's your Research?

 I am studying to disclose a general principle of auxin action, which is a plant hormone with various effects.

     Without the transport or effects of auxins, plants cannot produce leaves, flowers and roots. This is one example of how auxins play an important role in the formation of lateral roots (top right figure). Auxin transport changes in response to the direction of light or gravity (bottom right figure) and leads to stem bending, which is described in the textbook. Auxin response determines the shape of the plant in various ways like this, but it is not well understood how this small chemical performs these different physiological responses. Our group pursued the expression of an early auxin-inducible gene in detail. By constructing a special microscope and refining imaging techniques (top left figure showing microscope and bottom left figure showing Arabidopsis plants which emit the bioluminescence of the luciferase reaction (firefly gene)), physiological response and auxin response have been unveiled together (bottom right figure).



What's Your Next Step?

By refining microscopy techniques, we were able to trace the time course of gene expression. This is just a process of data recording, but comparing this data in various auxin mutants revealed that there is a certain order of auxin response. I named this phenomenon "remodeling of auxin response." We hypothesize that different procedures used to remodel the auxin response make for different auxin responses. With this evidence and hypothesis, I may have one of the two answers mentioned above, "how they were made." Now, I am trying to answer the next one, "why this type of process is necessary." In order to achieve this answer, unveiling the evolution of the auxin response is necessary. Now it is believed that auxin has existed since the early stage of plant evolution, so having a history this long and being so widespread, it is difficult to get to the bottom of.


For Potential Students of Hokkaido University

My current research calls on many of my past experiences. In other words, any past experience and knowledge can be useful for you. Would you like to use your experience and knowledge in my laboratory to discover your potential and more? If you are interested in my research, please visit my website above and feel free to contact me by e-mail.



(1) Masaaki K. Watahiki and Kotaro T. Yamamoto, Visualization of Auxin Response. Signal Transduction of Plant - Molecule and Response (ookishin outouno kashika. shokubutsuno shigunarudentatsu - bunshino outou, in Japanese), Kyoritsu Syuppan, 2010, 210-215 (ISBN978-4-320-05703-6)