This year’s Best Student Paper Prize in ‘Molecular Plant Pathology’ was won by Jiming Li who studied Fusarium oxysporum during his studies in Martijn Rep’s Molecular Plant Pathology group at the University of Amsterdam, Holland.
We got in touch with Jiming to find out more…
It would be really interesting to know what got you into plant pathology?
I am from the countryside, and I have been fascinated with plants since I was a kid. I, together with my sister, started to plant all kinds of vegetables, flowers, and trees in the garden since I was around six years old. I am very proud that the grapevine I planted in my parents’ garden has been happily growing for almost 20 years. It is not surprising that I chose biology during my bachelor’s study. Then I decided to focus on plants during my masters, and the project was plant diseases related. I became quite interested in plant diseases at that time. I was quite sure that I would continue to study plant diseases during my PhD. When I was searching for a PhD position, the horizontal chromosome transfer phenomenon in Fusarium oxysporum (F. oxysporum) caught my attention. I was super excited when I got the scholarship to study F. oxysporum with my supervisor Professor Martijn Rep in the Molecular Plant Pathology group at University of Amsterdam.
What was it like working with the Molecular Plant Pathology team in Amsterdam?
This was my first time abroad but I got used to this new environment very quickly and the Netherlands is super nice and organised. A great place to be.
For me, it is the best research group with a great atmosphere. My colleagues were always ready to help whenever I needed them. My supervisor is very nice, and I did not have a single unhappy moment with him. He encouraged me a lot and gave me any support that I needed. I have so many beautiful memories in the group, and I already miss them.
How does Fusarium oxysporum infect Cucurbits?
F. oxysporum is a soil-borne fungus and is very common worldwide. To infect Cucurbits, F. oxysporum first penetrates the root and then grows inside of the root. Eventually, the fungus reaches the xylem vessels of the roots and then spreads to the main root and stem in susceptible plants.
Why is it useful to study F. oxysporum?
F. oxysporum is known to cause disease on a large number of plant species, including many economically important crops, such as tomato, cucumber, melon, and watermelon, and is ranked the fifth most important fungal plant pathogen. It causes severe disease, rots the roots and plants can completely die in one week. Understanding how this fungus infects its host may give leads on how to improve breeding strategies and agricultural practices and thus impact our food industry.
In your paper, F. oxysporum is described as a fungus which lives in lots of plants, but often doesn’t cause disease. Can you describe how your work adds to this story?
Although F. oxysporum can cause disease in many plants, most do not. These F. oxysporum strains can live inside of the plants without causing disease. These strains probably lack virulence genes to cause disease or they are recognized by the plant immune system. My study adds to this story by identifying areas of the pathogen genome responsible for causing disease.
Chromosome transfer in F. oxysporum is a very interesting phenomenon. These mobile pathogenicity chromosomes carry all the elements that are required for infecting certain plant species. If a non-pathogenic F. oxysporum strain receives the mobile pathogenicity chromosomes, it (most likely) will become pathogenic to certain plants. In this research, I showed that the non-pathogenic F. oxysporum strain became pathogenic to melon plants when it received the mobile pathogenicity chromosome from a melon-infecting strain.
Do you have a favourite technique or experiment from this research and why?
In this research, my favourite experiment is the horizontal chromosome transfer. I labelled the chromosome regions with selective markers and grew two isolates on a plate with selective chemicals. The fungal strains which survive contain the labelled sections of genome. I then studied virulence of these strains on plants. By performing this experiment, I was able to identify the key chromosomes that are required for infecting plants. It is also exciting to observe that the non-pathogenic strains became pathogenic after receiving the chromosomes.
This study led you on to the discovery of a potential effector gene which may be important for F. oxysporum infecting Cucumber.
Did you think you were going to find this candidate effector when you started?
No, not at all. I had two projects during my PhD and the other project was really tough and didn’t give many results for the first two years. So, we chose to work on this project. The techniques I used were developed from ~20 years of study in F. oxysporum on tomatoes, with a Nature paper in 2010 on Horizontal Chromosome Transfer.
In this current study, we identified mobile pathogenicity chromosomes in F. oxysporum determining host range on cucurbits. By continuing this study during my PhD, we identified a single gene that limits host range.
How did it feel to make this discovery?
This discovery was obtained at the end of my PhD, and I was lucky and excited about the results. The discovery not only is the perfect ending of my PhD career but also helps a student at the University of Amsterdam to get the funding for her PhD to continue this line of research in the Molecular Plant Pathology group. I am excited and look forward to the discoveries from it.
Where do you see yourself in the future?
After my PhD, I came back to China to study plants again in Beijing Genome Institute (BGI Shenzhen). Currently, I study the molecular mechanisms of plant regeneration using the single cell sequencing technology. My career will always be plant-related. My passion and love for plants have never changed.
Well done on writing the Best Student Paper for 2020 in Molecular Plant Pathology! What advice would you give to a student just starting their PhD?
Looking back on my PhD, I have some advice for students just starting their PhD. First, doing a PhD will not be a smooth journey, so it would be wise to be mentally prepared. Second, having regular meetings with your supervisors and keeping a good relationship with them are very important. Thirdly, it is healthy to be optimistic and believe in yourself. Last but not least, PhD is not everything, so please do not forget to enjoy your life with friends and family.
Jiming’s supervisor, Martijn Rep: “Jim has energetically carried forward our work on pathogenicity chromosomes in Fusarium oxysporum, identifying mobile pathogenicity chromosomes in melon-infecting strains. This has opened the way to investigate the genetic determinants of host-specificity in cucurbit-infecting strains. Jim has himself subsequently discovered such a determinant: a putative effector gene that prevents infection of cucumber, also recently accepted for publication in MPP. I am really happy with Jim’s qualities and contributions.”
Jiming Li, Like Fokkens, Peter van Dam and Martijn Rep