Salim Bourras

Academic and Professional Background

My academic career began with an MSc in Life Science and Technology from AgroParisTech Engineering School, France (2008), followed by a PhD in Biology from University Paris-Sud 11 (2012). My doctoral thesis focused on the pathogenomics of Leptosphaeria maculans, establishing my research foundations in fungal genetics and genomics.

I then moved to the University of Zurich, Switzerland, first as a Postdoctoral Research Associate (2012-2016) and subsequently as a Junior Group Leader (Oberassistent) (2016-2018). In 2018, I was recruited to SLU as an Assistant Professor, establishing my independent research group. I was promoted to Associate Professor in 2022 and hold the title of 'Docent', Sweden's highest academic qualification for teaching and research, supported by extensive pedagogical training from SLU. In 2024, my group joined the Department of Plant Biology.

My research group, Plant Immunity and Plant-Microbe/Microbiome Interactions, investigates the fundamental biological questions at the heart of plant-pathogen co-evolution. We use cereals -primarily wheat, oat, and their wild relatives- as our primary model system.

The program is centered on basic, hypothesis-driven science. We aim to dissect the molecular "arms race" to understand, at a mechanistic level, how plants detect pathogens and how pathogens, in turn, evade this detection. The genetic and molecular knowledge generated from this fundamental work provides a direct and rational basis for translational applications in sustainable agriculture and crop improvement.

Core Research Themes

My group's research is organized into three interconnected themes:

1. Effector-NLR Biology and Novel Immune Mechanisms

A primary line of inquiry focuses on the molecular dialogue between pathogen effector proteins and the plant's intracellular (NLR) immune receptors. We seek to understand the genetic basis of recognition, specificity, and immune signaling. This work has been central to identifying and functionally characterizing key avirulence (Avr) genes from the wheat powdery mildew pathogen (e.g., AvrPm3, AvrPm2) and elucidating how they are recognized by their corresponding host resistance (Pm) genes. We also explore non-canonical immune pathways, including the role of small RNAs (sRNAs) and domesticated high-copy transposons in the wheat immune response, and the application of cross-kingdom RNAi for quantitative resistance.

2. Plant Social Behavior and Neighbor-Modulated Immunity (NMI)

A new and expanding research focus in my lab investigates how plants interact with each other in a community. We are moving beyond the individual plant to ask: How do plants cooperate or compete, and how do these "social" interactions shape their collective development and immunity? This program explores:

• Neighbor-Modulated Immunity (NMI): The genetic basis of a plant's ability to induce resistance or susceptibility in its neighbors.
• Genetic Architecture: We test the hypothesis that complex social traits are controlled by a few major, Mendelian loci, making them genetically tractable.
• Domestication Effects: We investigate how domestication and modern breeding -which has focused on "monoculture" performance- may have counter-selected for these crucial cooperative social traits.

3. Translational Genomics and Strategic Initiatives

This theme translates our fundamental discoveries into practical tools and resources for the breeding and scientific community. We refer to this as the "Architect" approach: using predictive genomic models to design elite, cooperative "dream team" crop mixtures in silico, bypassing the slow, observational "Artisan" method. This work is embodied in two key initiatives I lead:

• The Nordic Oat Taskforce (NOaT): As founder and coordinator, I established this network of academic and industry partners to develop next-generation genetic resources for Nordic oat breeding.
• The SLU Plant Clinic: I am a key expert in this institutional resource, providing high-level diagnostics for plant diseases and connecting our molecular research directly to real-world pathology challenges.

Supervision and Mentoring

I am actively involved in the training and supervision of graduate students and postdoctoral researchers. My supervision philosophy is centered on providing a rigorous, supportive, and collaborative research environment that equips early-career scientists with the skills for independent research.

Supervised Personnel

PhD Students (Major Advisor)

Dr. Kaitlin McNally (United States) - 2017 | University of Zurich
Dr. Coraline Praz (Switzerland) - 2019 | University of Zurich
Dr. Luisa Schaefer (Germany) - 2020 | University of Zurich
Dr. Stefan Lindner (Germany) - 2020 | University of Zurich
Dr. Marion Müller (Switzerland) - 2021 | University of Zurich
Dr. Lukas Kunz (Switzerland) - 2022 | University of Zurich
Dr. Jonathan Isaksson (Finland - United States) - 2023 | University of Zurich

PhD Students (Co-Advisor)

Dr. Manuel Poretti (Switzerland) - 2021 | University of Zurich
Dr. Carol Kälin (Switzerland) - 2024 | Swedish University of Agricultural Sciences
Eula Gems Oreiro (Philippines) - {exp. 2026} | Swedish University of Agricultural Sciences

Postdoctoral Fellows

Dr. Miguel Angel Corrales Gutiérrez (Spain) - Major Advisor (2022-2024) | SLU
Dr. Shirin Akhtar (Bangladesh) - Co-Advisor (2019-2020) | SLU
Dr. Miguel Angel Corrales Gutiérrez (Spain) - Co-Advisor (2024-curr) | SLU

MSc Students

Total Supervised: 14
Main Advisor: 10
Co-Advisor: 4

BSc & Project Students

Total Supervised: 6 (all as Main Advisor)

My academic role includes extensive involvement in graduate and post-graduate education. I serve as Course Leader and Examiner for the MSc course "Advanced Plant Pathology" and the PhD course "Pathobiomes and plant immunity" at SLU. My group actively trains PhD students and postdoctoral researchers.

I maintain an active role in the international scientific community through editorial service (Editorial Board for BMC Hereditas, Review Editor for Frontiers in Plant Science) and as an expert reviewer for high-impact journals and major funding agencies, including the European Research Council (ERC), the Swiss National Science Foundation (SNSF), and the French National Research Agency (ANR).

My research program is built on strong international collaborations with leading institutes, including the University of Zurich, Agroscope (Switzerland), IPK (Germany), and CREA (Italy).

A complete publication list is available on Google Scholar.

10 Selected Publications

[1] Kunz L, Poretti M, Praz CR, Müller MC, Wyler M, Keller B, Wicker T , Bourras S (2024) High-copy transposons from a pathogen give rise to a conserved sRNA family with a novel host immunity target. Molecular Plant-Microbe Interactions *Corresponding author.

[2] Mueller MC, Kunz L, Schudel S, Kammerecker S, Isaksson J, Wyler M, Graf J, Sotiropoulos AG, Praz CR, Wicker T, Bourras S, Beat Keller (2022) Ancient variation of the AvrPm17 gene in powdery mildew limits the effectiveness of the introgressed rye Pm17 resistance gene in wheat. Proceedings of the National Academy of Sciences (PNAS). 119: e2108808119 *Corresponding author.

[3] Lindner S, Keller B, Pal Singh S, Hasenkamp Z, Jung E, Müller MC, Bourras S and Keller B+ (2020) Single residues in the LRR domain of the wheat PM3A immune receptor can control the strength and the spectrum of the immune response. The Plant Journal, 104: 200-214 *Corresponding author

[4] Schaefer LK, Parlange F, Buchmann G, Jung E, Wehrli A, Herren G, Müller MC, Stehlin J, Schmid R, Wicker T, Keller B and Bourras S (2020). Cross-Kingdom RNAi of Pathogen Effectors Leads to Quantitative Adult Plant Resistance in Wheat. Front Plant Science, 11:253. *Corresponding author

[5] Poretti M, Praz C, Meile L, Kälin C, Schaefer LK, Schläfli M, Widrig V, Sanchez Vallet A, Wicker Tø and Bourras S (2019). Domestication of high-copy transposons underlays the wheat small RNA response to an obligate pathogen. Molecular Biology and Evolution, 37: 839-848. *Corresponding author.

[6] Bourras S, Kunz L, Xue M, Praz CR, Müller MC, Kälin C, Schläfli M, Ackermann P, Flückiger S, Parlange F, Menardo F, Schaefer LK, Ben David R, Roffler S, Oberhaensli S, et al. (2019). The AvrPm3-Pm3 effector-NLR interactions control both race-specific resistance and host-specificity of cereal mildews on wheat. Nature Communications, 10: 2292. *Corresponding author.

[7] Praz CR, Menardo F, Robinson MD, Müller MC, Wicker T, Bourras S and Keller B (2018). Non-parent of origin expression of numerous effector genes indicates a role of gene regulation in host adaption of the hybrid triticale powdery mildew pathogen. Frontiers in Plant Science, 9:49. *Corresponding author.

[8] McNally KE, Menardo F, Lüthi L, Praz CR, Müller MC, Kunz L, Ben-David R, Chandrasekhar K, Dinoor A, Cowger C, Meyers E, Xue M, Zeng F, Gong S, Yu D, Bourras S and Keller B (2018). Distinct domains of the AVRPM3A2/F2 avirulence protein from wheat powdery mildew are involved in immune receptor recognition and putative effector function. New Phytologist, 218:681-695. *Corresponding author.

[9] Praz CR, Bourras S+, Zeng F, Sánchez-Martín J, Menardo F, Xue M, Yang L, Roffler S, Böni R, Herren G, McNally KE, Ben-David R, Parlange F, Oberhaensli S, Flückiger S, Schäfer L, et al. (2017). AvrPm2 encodes an RNase-like avirulence effector which is conserved in the two different specialized forms of wheat and rye powdery mildew. New Phytologist, 213:1301-1314. +Joint first author

[10] Bourras S, McNally KE, Ben-David R, Parlange F, Roffler S, Praz CR, Oberhaensli S, Menardo F, Stirnweis D, Frenkel Z, Schaefer LK, Flückiger S, Treier G, Herren G, Korol AB, Wicker T and Keller Bx. (2015) Multiple avirulence loci and allele-specific effector recognition control the Pm3 race-specific resistance of wheat to powdery mildew. The Plant Cell, 27:2991-3012.