Legendary confrontation between fungi and nematodes, pioneer of non-model species-Xue Yanbing

The duel between predators and prey is a very common and important phenomenon in the ecosystem. Xue Yanbing, an assistant researcher at the Institute of Molecular Biology, Academia Sinica, and his team observed how fungi hunt nematodes. From field collection, laboratory verification, establishment of better model strains, to self-developed analysis software, original research results were frequently published in international journals such as the Proceedings of the National Academy of Sciences (PNAS), and they were followed by the research.

Xue Yanbing, an assistant researcher at the Institute of Molecular Biology, Academia Sinica, holds a nematode doll in his hand, and a box of Petri dishes lives next to it. Photography/Zhang Yuchen

The first part < See how fungi kill nematodes and open a new dawn of parasite treatment drugs! According to the article, Xue Yanbing's team discovered the hunting scene in the micro-world: nematodes were trapped by trapping bacteria and Pleurotus eryngii was poisoned to prey on nematodes. These insecticidal mechanisms will bring new possibilities for biological control. But what is more precious is that when Xue Yanbing began to study this topic, scientists knew little about these molecular mechanisms of interaction between insect-eating fungi and nematodes, and she was a pioneer.

"Scientists estimate that there are about five million kinds of fungi on the earth, but at present, researchers really know only more than ten kinds of fungi, such as yeast, bread mold and some pathogenic bacteria. But there are some very interesting fungi in nature, and there is almost no molecular research. Xue Yanbing emotionally recalled: "I am very grateful to Paul Sternberg, my advisor of postdoctoral research at California Institute of Technology, for his willingness to support my idea and let me try to open a new field in his laboratory, and use the model nematode C. elegans to explore the predator-prey interaction, molecular mechanism and coevolution between insect-eating fungi and nematodes. After returning to Taiwan Province, China, and establishing his own laboratory in Academia Sinica, Xue Yanbing continued to lead the team to expand the research on insect-eating fungi and pieced together the molecular mechanism of insect-eating fungi killing nematodes step by step.

But it's not easy to be a pioneer. From finding valuable original themes, building better model organisms, and even building analytical tools, you have to face greater unknowns every step forward. However, due to the original contribution, the research results are frequently published in international journals such as Proceedings of the National Academy of Sciences (PNAS). Walk into the research site of Xue Yanbing's team together!

collecting in the field, and verifying that the experiment is not utopian

Xue Yanbing's team found that A.oligospora preys on C.elegans through five steps: attracting prey → finding prey → setting a trap → catching prey → having a full meal.

BUT！ In nature, do nematodes and nematodes-trapping bacteria really meet and "hit it off" as in the laboratory? So Xue Yanbing's team shuttled between China, Taiwan Province and Shan Ye for collection. It was found that two-thirds of the soil in Taiwan Province, China had nematodes, and nematodes were the most abundant animals, so they were often "together".

In order to study the interactive relationship between nematodes and nematodes-trapping bacteria in nature, Xue Yanbing's team must collect them from China, Taiwan Province and Shan Ye, isolate various nematodes and fungi from the soil, and sort out which nematodes will grow with which nematodes-trapping bacteria in nature. Source/Xue Yanbing; Photo Reproduction/Lin Juan 'an Source/Xue Yanbing; Photo reproduction/Lin Juan' an

They also separated various nematodes and fungi from the soil, sorted out which nematodes and nematodes-catching bacteria grow together in nature, and tested their interaction in the laboratory. For example, does a certain nematode-catching bacteria eat all nematodes? Or just eat a few nematodes? It was found that the nematode trapping bacteria "don't choose to eat" and eat all kinds of nematodes. The hunting relationship really "exists universally" between all nematodes and nematode trapping bacteria.

Finding super-strong strains and establishing good research materials

During the research, Xue Yanbing also found that the standard strains of nematodes captured from the strain center were "a little weak", which was not conducive to the research. What should we do? Build your own new model! They found some strains with strong hunting ability from the nematodes collected in the field. These strains can produce many capture structures, and the speed of growing capture structures is relatively fast, so the speed of killing nematodes is also fast! These super-strong strains can be excellent model strains, making it easier for scientists to study how nematodes grow capture structures and which genes are needed to capture prey.

Xue Yanbing also used genome sequencing and genome elimination to solve the hunting secret of the super-strong strain: G protein! In the nematode trapping bacteria, G protein is responsible for transmitting external signals to cells. Xue Yanbing found that this protein can transmit signals that nematodes are infested in the outside world and promote cells to grow trapping structures. Without this protein, the nematode trapping bacteria can't develop the trapping structure, so they can only let the "fat worm in the mouth" escape ~

The experimental samples of nematodes and fungi should be searched patiently, and the tools for analyzing their fighting defense should be developed painstakingly. If you once put bread into mildew, and suddenly look back one day, you will find that bread grows pieces of mold hyphae, and it is difficult to accurately describe its growth speed, growth range and mycelium length. The nematode trapping bacteria (fungi) in the laboratory are in a similar situation.