It's been 100 years since Wageningen University & Research (WUR) started working on phytopathology. Over the past century, the department has nurtured the careers of leading scientists and produced groundbreaking research in the field of plant disease. Researcher Joeke Postma and chairholder Gert Kema explain how their professional field has changed over the years and discuss the specific developments that have driven those changes.
Controlling plant disease is crucial to food security. Viruses, fungi, and bacteria have the potential to devastate entire harvests, leading to severe famines. How exactly do pathogens cause disease in plants? And how can we make plants more resilient? "These questions have been the primary focus of the Phytopathology department for a century now. However, while the core challenge has remained consistent, Joeke Postma, a researcher at Wageningen Plant Research, notes significant changes in a myriad of related issues.
"Just think of all the types of pathogens. Factors such as climate change and new types of agricultural systems have meant that lots of pathogens have emerged while others have vanished. Fungi and viruses are themselves also constantly evolving, partly as a result of the cultivation of new crop breeds and resistant varieties."
Faster data collection and processing
Postma first joined Wageningen in the late 1970s as a student. "One of the first research projects I worked on was about the ecology of soil pathogens. I was supervised by Gerrit Bollen on that. The question was whether adding compost to soils would make them able to suppress plant pathogens. The compost we used came from Belgium because disease-suppressive compost wasn't yet available in the Netherlands. I isolated as many microorganisms out of the compost as I could. In order to identify fungi, I had to examine their morphological characteristics under a microscope. That was real drudgery. Identification based on DNA sequencing didn't exist back then. The collection and processing of large quantities of data are much faster now."
Emergence and role of molecular technology
DNA sequencing is an example of molecular technology. The emergence of molecular technology has led to huge changes in the field of plant pathology research, says Gert Kema, chairholder in Phytopathology at WUR. "It has enabled us to look at and describe diversity in an entirely new way. This has led to some extraordinary findings. One of the most important results within our department came out of the work of the group led by my predecessor, Pierre de Wit. In the early 1990s, they were the first to clone a fungal avirulence gene. The gene is recognized by resistant varieties, which means those plants don't get sick. This work has had a profound and lasting impact on phytopathology and plant breeding."
Greater focus on tropical crops
Kema started at Wageningen in 1982, conducting research on yellow rust in wheat. He also spent many years working on septoria leaf spot and obtained his PhD on that topic under the supervision of Jan Zadoks. Since 2004, Kema has been part of a team doing research into banana diseases. "When I started doing that, my co-workers laughed at me. 'Why would we study bananas in Wageningen, they're just a fruit!' But bananas are a crucial food crop for millions of people around the world. That was something I really needed to explain to people. Now, everyone thinks it's great, and they recognize the urgency. Over the past decade, the department has also started focusing more on other tropical crops, such as cocoa and oil palm. That kind of research requires really good collaboration with overseas partners, which is a lot easier now than it was in the 20th century."
Collaboration with other disciplines and partners in the field
These days, collaboration plays a big role overall at Wageningen. "Research into plant diseases requires not just knowledge of plants and pathogens, but also of ecology and soils, for example," says Postma. "We try to pool those areas of expertise as much as possible. When I was first starting out, I had to fight to collaborate with other disciplines. Personally, I always insisted that we needed to focus on soil life. I'm rather proud that there's a broad consensus now within phytopathology on the importance of this. And certainly, within Wageningen Research, we're always looking for mutually beneficial opportunities with partners in the field. Those relationships enable us to work on the problems that are most relevant in practice, which then amplifies the impact of our research. Collaboration is also important because we're increasingly dependent on private-sector funding."
Sustained leadership in phytopathology
According to Kema, it's difficult to state unequivocally the extent to which the department in Wageningen has contributed to combating plant disease over the past century. "First of all, it's unrealistic to think that we can totally eradicate any plant disease across the whole world. At best, we might be able to do so locally. Globalization and climate change have only exacerbated the challenges. But eradicating diseases isn't even our objective in the first place. We're mainly focused on understanding the interaction between plants and pathogens and on increasing the resilience of crops. And in that sense, WUR has long been a leading player in the research world, not least in the field of diseases affecting grains and potatoes."
A better understanding of infection and protection processes
Finally, what developments do the researchers expect to play a prominent role in phytopathology over the next few years? Postma expects that micro-level research will be one of the drivers of the field. "At the moment, we often work with composite soil samples where everything is homogenized. But that doesn't allow you to observe the physical interactions between a fungus, other soil organisms, the soil matrix, and a plant's root system. If we had a better understanding of that, we would develop a better understanding of the processes of infection and the protection provided by soil life."
Artificial chromosomes and data integration
Kema is impressed by the development of artificial chromosomes. "If we see success in the further development of those, we may be able to simulate resistance genes. Aside from that, I also expect artificial intelligence (AI) to trigger major changes. I also see a lot of potential within multidisciplinarity and data integration. If you were to integrate information about things like the weather, soil, fungi, and plants into a single platform, you'd get an even clearer perspective of the levers you need to turn in order to increase crop resilience or productivity. There's still so much to discover and improve, and that's what makes this field so fascinating and forever relevant."