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Studying growth in plants

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Zining Wang

3nd-year doctoral student, Department of Biological Sciences (GR)

From

The University of Chinese Academy of Sciences, Beijing

Chaina

A growing interest in growth

I got interested in science in junior high school after reading a few popular science books that introduced me to science. I read these books as if I was reading interesting novels, but they revealed truths about the universe rather than being mere fiction. I was particularly fascinated by the stars and other objects far away from our everyday lives. Then, as a high school student, I competed at the Science Olympiad. The Olympiad has many levels, from the local, such as the one I entered in my hometown, to international competitions.

Unfortunately or not, astronomy was not generally available as a subject in which to compete. So, I tried many subjects, and biology stuck. Even though I did recognize the fundamental importance of math and physics, solving abstract equations somehow did not come naturally to my mind at that time. But biology answered questions such as “Why do we have five fingers?” or “Why does hair grow and fall out?” So, ultimately, biology answered questions about ourselves, which attracted me to it. I won second prize in chemistry and first in biology in my home province in China. I felt compelled by science because while preparing for these competitions, I saw how the world worked, more than mere human imagination. My participation in the Olympiad also paved the way for me to continue studying science at college.

Even freshmen do work in the lab

I went to the University of Chinese Academy of Sciences, a huge institution in Beijing, the capital of China. I lived in a dormitory with five roommates. As students at this college could freely change their major until the third year. There were many opportunities to explore. Moreover, everybody had to join a lab, even freshmen. On weekdays, we had lectures, and on weekends, we tried our hands in the lab. First, I joined the Institute of Microbiology and studied how bacteria moved by sensing environmental attractors and repellents. I found, however, that experimental biology often studies phenomena without the underlying physics. I might have also been influenced by my roommates, three of whom studied computer science and two of whom studied physics, when I joined the Institute of Physics to study biophysics in my third and fourth years. There, I studied how the chromosomes and DNA were moving around inside the cell. DNA is tiny, about two nanometers in diameter, and can only be seen using high-spec microscopes. I used an atomic force microscope (AFM) to study in vitro DNA and a confocal microscope to study living chromosomes. Slowly, however, I realized I was interested in studying things with dynamic changes at larger scales, for example, visible to the naked eye. And that is what I am studying now: how leaves and other plant organs grow from a tiny chunk of several hundred cells into an organ with diversified shapes visible to naked eyes.

Changing gears and changing countries

After doing biophysics for the last two years of my undergraduate studies, I wanted to change gears while furthering my education. My professor suggested studying abroad to experience research in a different part of the world. I considered various options, including the Americas and Europe. I chose Japan because I felt it was both physically and culturally the closest. I like working at night, so I also wanted to choose a destination known for its safety and infrastructure amenable to such a lifestyle. And Japan is famous for its 24-hour chain restaurants and convenience stores. Once I decided to continue my studies in Japan, it was clear that I would aim for the best institution in the country, the University of Tokyo. I was lucky because one of my lecture’s professors in China knew Professor Tsukaya, my current supervisor, and recommended me to him. Of course, I still had to jump through the hoops: I took the GRE* and the entrance examination. I passed the exam. And I was luckily accepted by the (GSGC Global Science Graduate Course), a scholarship program offered by the University of Tokyo. This program generously covered my living expenses, providing a monthly scholarship of 180,000 yen throughout the five years of master’s and PhD studies. Moving to Japan also allowed me to pursue my original research interests, things growing “outside,” visible to human eyes.
* Graduate Record Examination

Concave versus convex leaves

I like plants and observing how they grow from the point of germination into saplings and eventually into trees. The leaves of a plant grow out from a group of cells called primordia. From these tiny cells, we can see the growth of the leaf. I am fascinated by these transformations as cells divide and create leaves with diversified shapes. My new research subject is a plant species in the genus Oxalis. It is the third most widely distributed plant species, found in about 50% of terrestrial regions. It has heart-shaped leaves with tips bending inwards, or what is called a concave apex. The opposite of this shape is called a “convex apex,” which refers to a sharp tip. Although botanists have known about and classified various shapes like concave and convex apices for the past 200 years, how these shapes develop is still a mystery. One of the difficulties is that majority of researchers only studied model plant Arabidopsis, like animal researcher study mice. And unfortunately, the leaves of Arabidopsishave a relatively simple shape compared to various non-model plants, thus limiting researchers in examining more complicated shapes.

Simulating growth

My research interests lie in the fundamental principles that give rise to the diversified shapes we observe. To construct a general model, I do computer simulations of cell division and growth and compare the results to growth observed in real plants to check if my assumptions for the model were correct. I learned to code in college (and by watching many tutorials online). I find it a fun and efficient research method with relatively low costs and high performance. In the simulations, I can assign cell division angles to the simulated cells, for example, to divide in the vertical direction, forming a tip, or in random directions, forming a circular base. The simulation also has a surprising connection: I am using a model developed by a professor who was the supervisor of one of my current supervisors. In my research, I have previously found that the tip of the leaf is a result of cells dividing in the proximal-distal direction along the line we can draw through the middle of the primordium.

… but does the model reflect how a real plant grows?

To verify my model, I have to check if it is "growing" the same way as a real plant. The real plants are grown in the lab’s chambers and greenhouse and I take samples of cells at various stages of development. The first stage of leaf sample is of the primordium, about 200 micrometers long, the size of a dust particle. As cells divide and plant grows, I use a staining method developed in our lab to see how each pair of daughter cells divide from the mother cell. Then, I can compare my results to my simulation. I also enjoy watching the plants grow. Huge trees in the wild might take a very long time to grow, but the plants I use germinate quickly. I can catch a glimpse of the growing leaves in about eight days (depending on the species). From there, I can observe how a leaf that initially looks like a thin rod expands into the base, growing from a small, young leaf to a fully mature one with a sharp tip (depending on the species). I have submitted a paper about my latest research to a journal, so now I am waiting for peer-review feedback. I am a little worried about being judged. Even if I think I have enough evidence, others might not agree. But this is science: you always need to welcome judgement and criticism.

Learning terminology in Japanese

I learned Japanese by myself while I was doing my undergraduate studies. I used the standard textbook created by the Chinese and Japanese governments. I also watched a Japanese language-learning TV show originally aired 20 years ago. If you are not a native Chinese speaker and these resources are not available, online tutorials can also be helpful. There might be many people out there who love anime, which could be a fine tool to practice listening. However, “anime Japanese” is quite different from real-life Japanese, so watching Japanese live-action TV shows might serve language learners better. To those who are struggling with English, I suggest the same. I watched Friends and Downtown Abbey to practice understanding both American and British accents. Lastly, do not be afraid to make mistakes when speaking. Even today, I had a bit of trouble understanding what the cameraman was saying. My Japanese was not perfect, but I managed! I also recommended language learners to set clear goals, such as being able to communicate with native speakers or preparing for the JLPT (Japanese-Language Proficiency Test). For my studies, I got used to the Japanese terminology thanks to the many conferences I attended and the Japanese textbooks, which were quite challenging to read at first!

A historical perspective

Basic science is complicated. But trying to understand how the world around us is built up is endlessly fascinating, too. Doing basic science allows you to acquire already existing knowledge and discover new principles on your own. If you go into industry, you might learn more about how society works, and making money might also be fun. Basic science is more “pure” in a sense. Many of my peers complained about the financial conditions in academia. I think, between two people with similar abilities exerting similar effort, usually the one working in industry tends to earn a higher salary. Historically, scientific study was considered a hobby for “gentlemen.” Most people were unable to pursue basic science: accessible knowledge was scarace and doing hard, manual work to make a living was commonplace even one hundred years ago. Having a safe roof over your head and money to eat as much as you want is historically rare but common in our modern era. A higher salary may afford a higher standard of living right after your undergraduate studies, but if you are interested in the natural world, then entering a doctoral program first and deciding what you do after might also be a good choice. I intend to pursue an academic career, which might mean working longer hours and getting less paid. But it is still fascinating work funded mainly by taxpayers. So, I think it is a fair setup, getting paid to do basic science that does not have direct and immediate economic rewards but benefit future generations.

※Year of Interview:2024
Photography:HASEGAWA Hirokazu
Text:Belta Emese
The interview was edited for brevity and clarity.

Zining Wang
3rd year doctoral student, Department of Biological Sciences (GR)
Born in Zhejiang Province, China. Enrolled in the Biological Sciences major of the University of Chinese Academy of Sciences in 2016. Has been studying in the Department of Biological Sciences, Graduate School of Science (GSGC) since September 2020. Planning to continue his research as a postdoc after PhD graduation.
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