Expert chat with Dr. Jiue-In Yang, Assistant Professor, Department of Plant Pathology and Microbiology, National Taiwan University (NTU), Taipei

Dr. YangIn this interview,  Dr. Jiue-In Yang, Assistant Professor at the Department of Plant Pathology and Microbiology, National Taiwan University (NTU) in Taipei, Taiwan, talks with us about her work, her professional background and what she thinks is key to solving nematode problems in her country.

After receiving her Bachelor of Science degree from NTU, Dr. Yang took a position as Plant Quarantine Officer at the Hsinchu branch of Bureau of Animal and and Plant Health Inspection and Quarantine, Council of Agriculture , located at the Taipei Taoyuan Internationl  Airport. In 2007, she moved to the United States for a PhD student position with Professor James Borneman (Department of Plant Pathology and Microbiology) and CE Specialist Ole Becker (Department of Nematology) at the University of California, Riverside. Her doctorate research focused on the microbiome analysis of different pathosystems and biocontrol agents, such as Pochonia chlamydosporia and Dactylella oviparasitica. She successfully defended her dissertation on peach replant disease and nematophagous fungi in 2015 and returned to NTU to focus on solving nematode problems in the region. Now as Assistant Professor for the University where she started her career, Dr. Yang notes, “I never expected myself to become a professor, but I am enjoying it a lot.”

Dr. Yang, what do you enjoy most about your work?

What is really key to my work as a plant pathologist is to understand the pathosystems that are causing yield losses in farmers’ fields or that are listed as quarantine items constraining export. For that, I need to talk to people – growers and advisory and quarantine services. Half of my work is applied and the other half is basic research with both ultimately focused on supporting growers. That is really what I love about my work. I study nematodes and their interaction with their hosts and also develop molecular tools to identify diseases. The discoveries are relevant to science, growers and other groups such as quarantine services. I also provide training advisory services. In Taiwan, there are not many plant nematologists – at the moment only three – and the economic impact of plant parasitic nematodes on crops is underestimated due to the lack of awareness. As a nematologist, I feel my mission is to do my best to develop more nematologists in my department for the future of this region.

How do you approach problems in a  grower’s field?

If there is a problem with a crop in a field, I always recommend that the grower take some soil samples or some impacted plant tissue as the first measure. There are plant clinic services in District Agricultural Research and Extention Services (DARES) and in the College of Bio-Resources and Agriculture at NTU, where samples can be sent in and analyzed. The specialists in the clinic will identify the possible pathogens. Once the grower knows what the issue is, he or she normally goes to the nearby pesticide store and purchases nematicides or consults advisory services for a further management recommendation. Unfortunately, we do not have an extension service specialist at NTU, as many universities do in the US; therefore, when DARES advisors are not sure how to handle the problem, they often then turn to me for advice.

What are the key nematode species in Taiwan?

Root-knot nematodes and lesion nematodes are common on vegetables and fruits. Because rice is the most important cereal crop in Taiwan, growers are primarily concerned about rice leaf nematodes (Aphelenchoides besseyi). This nematode is also a quarantine pest in European countries. Under the conditions in Taiwan, the rice leaf nematode life cycle can be completed in less than 12 days and can cause up to 70 % yield loss on a sensitive rice variety. It can also infect fern and strawberry; the latter, however, has not been that relevant in recent years. Lesion nematodes are more of a concern in strawberry fields. In addition, based on a recent survey, spiral nematodes and stunt nematodes are most common in tea growing regions, while root lesion nematodes and spiral nematodes are present in coffee plantations in Taiwan.

You also develop molecular tools to identify nematodes. What are the benefits over classical identification?

In my opinion, it is important to know what the question is, in order to decide which identification tool suits it better. For example, what classification level do we need to know about the nematodes in the sample? Do we really need to know what the species is, or is the genus level good enough? Rapid analysis, for example, is key for quarantine purposes and allows us to quickly know if a quarantine pest is present – because time is money when cargo is on hold during the quarantine test.

What do you think is most challenging about working with nematodes?

Global awareness of the economic impact of plant parasitic nematodes is generally quite low – likely due to the lack of trained personnel who can identify diseases caused by plant parasitic nematodes and even to rear the worms for nematological studies. In other words, it is difficult to obtain the relevant information on given topics even if one is interested in certain plant parasitic nematode species.

What is key to control nematode problems?

The key to controlling nematodes is to understand the biology and population dynamics so that one can select the right timing of its life cycle to apply management measures. The lifecycle length of nematodes is temperature dependent, meaning if researchers had local information about temperature conditions, the control measures could be more effectively planned. For instance, root-knot nematodes can complete one life cycle within 30-36 days at 28° C on mung beans. By taking a sample right after crop harvest and analyzing the initial nematode population in the soil, a researcher could estimate the nematode amount in the field at a given time using knowledge of degree-days required by the nematode. With that information, growers can make the decision to apply a nematicide treatment in the field or to switch to a different crop for the next season. After all, the best control would be to prevent nematode hatching by killing the eggs. Yet in my experience, most growers tend to replant the same crop immediately or rotate with the wrong crops that are also good nematode hosts; therefore, the nematode population builds up quickly, which leads to problems. In addition, the younger generation of farmers in Taiwan are concerned about the negative effect of nematicides on human health when applying them. They prefer more environmentally friendly chemical products with safer application procedures (e.g. drip application or seed treatments).

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