Zhongwei Zou
Department of Biology
Wilfrid Laurier University
Plant and microbe interaction represents a fundamental aspect of plant biology, particularly in terms of biotic stress response. However, teaching these concepts for undergraduate students presents a notable challenge due to their complexity. Plant immune responses can be broadly divided into three key steps: perception of external signals, signal transduction, and activation of defense responses. Traditional teaching mostly focuses on the two plant immune systems: pattern-triggered immunity (PTI) and effector-triggered immunity (ETI). PTI is initiated when plants detect molecules associated with pathogens, or cellular damage. One key challenge in teaching plant immunity is introducing the expanding and diverse list of receptors that detect these molecules, but that can be overwhelming for students. Complexity is increased further with ETI, as some pathogens have evolved virulent proteins (effectors) that suppress or bypass this immune response. Plants have also co-evolved mechanisms to recognize these effectors and activate an additional robust defense response. Conveying these interconnected processes requires thoughtful pedagogical approaches to help students grasp both the conceptual framework and underlying biological mechanisms.
Demonstration Teaching: To effectively integrate my research program and experience into teaching, I incorporate real-world crop–pathogen systems into the classroom as illustrative examples. Even a limited set of well-characterized, functional players in crop–pathogen interactions can significantly enhance student understanding and engagement, allowing them to connect abstract concepts with practical, biologically relevant scenarios. For example, I use the canola–blackleg interaction as a model system to illustrate both qualitative resistance (R gene–mediated resistance) (Figure 1) and quantitative resistance (adult plant resistance) (Figure 2). A lab and greenhouse tour further enhances student learning by providing hands-on exposure to fungal pathogens and plant disease symptoms. During these sessions, students observe the morphology of the pathogen and learn how major resistance (R) genes interact with Leptosphaeria maculans Avr genes to confer qualitative resistance. At later growth stages, the concept of quantitative (adult plant) resistance is introduced, demonstrating how multiple genes contribute to sustained protection in canola. This example allows students to better understand how effector-triggered immunity (ETI) and pattern-triggered immunity (PTI) operate in an applied agricultural context, bridging fundamental concepts with practical relevance.
Reflection and assessment:
1) Assignment: Students demonstrate their understanding of qualitative and quantitative resistance by clearly defining each concept, evaluating their advantages and limitations, and discussing their application in crop breeding programs. This assignment helps students simplify complex concepts and express them in more accessible language, enabling them to integrate these ideas across broader areas of plant science.
2) Activity: Students explore additional crop–disease systems that involve both effector-triggered immunity (ETI) and pattern-triggered immunity (PTI), broadening their perspective beyond the primary case study. This activity will be designed as a quiz or reflective exercise, providing students with opportunities to present their findings on diverse crop–pathogen systems. Through these activities, students will demonstrate their understanding of ETI and PTI in applied contexts.
3) Group Discussion: Students conduct comparative analyses of identified effectors and receptors between model plant systems and crop species, highlighting similarities, differences, and implications for translational research. An in-depth group discussion during the class will enhance students’ understanding of plant immunity, including the roles of various receptors, effectors, and signal transduction pathways.
Take away: Effective teaching and learning should extend beyond the textbook—bridging concepts to real-world applications, connecting model plant systems to diverse crop species, and linking classroom knowledge to field-based practice.
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Figure 1: Teaching example of effector-triggered immunity (ETI) in Brassica napus-Leptosphaeria maculans pathosystems (Credited: Vidushika Yapa Mudiyanselage & Zhongwei Zou)
Figure 2: Teaching demonstration of disease symptoms caused by effector-triggered immunity (ETI) cotyledon, and pattern-triggered immunity (PTI) stem cross section, infections in Brassica napus against Leptosphaeria maculans (Credited: Vidushika Yapa Mudiyanselage & Zhongwei Zou)
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Recommended Reading List
Bigeard J., Colcombet J., and Hirt H. (2015). Signaling Mechanisms in Pattern-Triggered Immunity (PTI). Molecular Plant, 8, 521–539.
Boller, T., & Felix, G. (2009). A renaissance of elicitors: perception of microbe-associated molecular patterns and danger signals by pattern-recognition receptors. Annual review of plant biology, 60, 379-406.
Dongus, J.A., Parker, J.E. (2021). EDS1 signalling: At the nexus of intracellular and surface receptor immunity. Current Opinion in Plant Biology, 62,102039
Dolatabadian, A., Cornelsen, J., Huang, S., Zou Z., and Fernando, W.G.D. (2021) Sustainability on the Farm: Breeding for Resistance and Management of Major Canola Diseases in Canada Contributing towards an IPM Approach. Canadian Journal of Plant Pathology, 44, 157-190.
Jones, J. D., Staskawicz, B. J., & Dangl, J. L. (2024). The plant immune system: From discovery to deployment. Cell, 187, 2095-2116.
Ramirez-Prado, J. S., Abulfaraj, A. A., Rayapuram, N., Benhamed, M., & Hirt, H. (2018). Plant immunity: from signaling to epigenetic control of defense. Trends in plant science, 23, 833-844.
Yamaguchi, Y., & Huffaker, A. (2011). Endogenous peptide elicitors in higher plants. Current opinion in plant biology, 14, 351-357.
