Symposium in Memory of Ádám Kondorosi

Zsófia Bánfalvi joined the Symbiotic Nitrogen Fixation Group under the leadership of Ádám Kondorosi in 1975 as an MSc student. She continued her research there in pre- and post-doc positions until 1989, focusing on mapping, identifying, and cloning the nodulation and nitrogen fixation genes of the soil bacterium Rhizobium meliloti. During a 20-month period in Gary Stacey's laboratory at the University of Tennessee, she studied nodulation genes of Bradyrhizobium japonicum, the symbiotic partner of soybean. Since the establishment of the Agricultural Biotechnology Center in Gödöllő, she has been leading the Potato Research Group. She has authored or co-authored more than 100 peer-reviewed research articles (2438 citations, h index=31) and supervised 12 PhD and 13 MSc students.

I have a Scottish Diploma in Agriculture (1965), an Honours Degree in Microbiology (1970); both from the University of Edinburgh and a PhD in Rhizobium Genetics from the University of East Anglia (1973). I worked at the John Innes Institute from 1970 to 1980. In 1970 I initiated Rhizobium research and built-up a research team during the next few years. In 1978/1979 I spent six months working with Barry Rolfe in Canberra. From 1980 to 1984 I was Head of the Soil Microbiology Department at Rothamsted Experimental Station. From 1984 to 2005 I worked at the University of Bristol, initially as Head of the Unit of Molecular Genetics, then Head of Microbiology, Head of Botany, Dean of Science and finally Pro-Vice Chancellor. I retired in 2005. Whilst at Bristol I spent almost half my time speaking at conferences and chairing/attending numerous external committees, particularly on genetic manipulation. In 2000 I was made a Knight Bachelor in recognition of my role in advising government on GM.

Professor emerita of Plant Biology at the University of Torino (Italy), she pioneered plant-fungal interaction studies. Using cellular, molecular biology and NGS techniques, she investigated mycorrhizal fungi focusing on their interactions with host plants, from the colonization process with the description of the so called pre-penetration apparatus, to the identification of signalling molecules, as the chito-oligosaccharides. She discovered fungal endobacteria, and by sequencing fungal and endobacterial genomes, she revealed how they modulate host-functional traits. PB belongs to national/international Academies, has been among the world- most cited researchers and is in the list of the top Italian scientists.

She has written popular science books (A Plant is not an Island, 2021; Plants, Us and Them, 2026) in which she talks about the issues that fascinate her.

Sierd Cloetingh is Utrecht University Distinguished Professor. His research field is Earth Sciences. He published more than 391 papers in international peer-reviewed journals and has been promotor of close to 80 PhD students of 18 different nationalities.

Currently he serves as Chair Regional Coordinating Committee Europe of the International Lithosphere Program. Past functions include President of the Academia Europaea, Member and Chair of the Board of Scientific Advice for Policy by European Academies (SAPEA), President of the Association for European Cooperation in Science & Technology (COST), Membership of the Scientific Council (2009-2015) and Vice-President of the European Research Council (ERC), President of the European Geophysical Society (1998-2000), President of the International Lithosphere Program (ILP, 2004-2017), Distinguished Professor of the Royal Netherlands Academy for Arts and Sciences (KNAW, 2006-2015), Editor-in-Chief of the international journal "Global and Planetary Change" and Chairman of the TOPO-EUROPE collaborative research program.

Sierd Cloetingh received honorary doctorates from six European universities and numerous medals and awards. He is member of the Royal Netherlands Academy of Sciences, the Royal Norwegian Academy, the Royal Danish Academy, the German National Academy for Technical Sciences (Acatech), the Heidelberg Academy, the Bavarian Academy of Sciences, the Royal Academy of Barcelona, the Academy of Sciences of Lisbon and honorary member of the Hungarian Academy of Sciences. He was distinguished in 2005 as Chevalier de Legion d'Honneur and in 2014 as Knight of the Royal Order of the Netherlands Lion for his contributions to science and European scientific cooperation in research and education.

Ray Dixon is a former co-Director of the JIC-CAS Centre of Excellence in Plant and Microbial Science (CEPAMS) and former Head of the Department of Molecular Microbiology at the John Innes Centre in Norwich, UK. He has pioneered research on genetic and biochemical analysis of biological nitrogen fixation for more than 50 years. In 1972, Ray successfully transferred the complete cluster of nitrogen fixation (nif) genes from Klebsiella pneumoniae to Escherichia coli, thus creating the first engineered diazotroph. Dixon’ s group have had a major impact on our understanding of how nitrogen fixation is regulated at the molecular level in response to environmental factors and in particular how multiple signals are communicated to the transcriptional apparatus via signal transduction pathways. Dixon also has extensive knowledge of the biological functions of genes required for the regulation, biosynthesis and activity of nitrogenases and the physiological conditions that favour nitrogen fixation. In collaboration with colleagues in China, Brazil and the USA, he is exploiting this knowledge for re-engineering diazotrophic endophytes that efficiently transfer fixed nitrogen to crops and developing strategies for the expression of nitrogen fixation genes in eukaryotes.

After working in the area of microbial bioenergetics, I started working on rhizobial-legume interactions when I joined Andy Johnston and Nick Brewin at the John Innes Institute (now John Innes Centre) in 1981. Initially I focussed on identifying R. leguminosarum genes involved in nodulation and symbiotic nitrogen fixation, moving on to understanding the biochemical roles of the nodulation (nod) gene products and the roles of bacterial polysaccharides in legume infection. My analysis of nod gene products and Nod factors led me into a study of Ca2+ fluxes during nodulation signalling, initially via a collaboration with Sharon Long and her colleagues. Working with pea nodulation mutants I identified the presence of the common symbiosis signalling pathway activated by rhizobia and arbuscular mycorrhizae. I subsequently worked with nodulation signalling in infection-defective mutants of Lotus japonicus and Medicago truncatula and was involved in the identification of several legume genes required for the symbioses, particularly focussing on requirements for root infection by rhizobia. After I retired, I spent some time working with Eva Kondorosi and her colleagues on NCR peptides and also coordinated a research programme on ash-dieback disease. I have been very fortunate throughout my career to collaborate with several outstanding colleagues who have helped push back the frontiers of knowledge.

Peter was born in Berlin Germany, then studied Biochemistry and Genetics at the University of Alberta (Canada), before completing at PhD in Genetics at the Australian National University in 1973. He then worked under an Alexander von Humboldt Fellowship in Hohenheim Germany, before developing a research and teaching career at the ANU in Canberra (1975 – 1988). He then took up the Endowed Chair of Excellence of Plant Molecular Genetics at the University of Tennessee (Knoxville, 1988-1999), before being appointed Head of the Botany Department/Head of School of Biological Sciences at the University of Queensland (St. Lucia, Brisbane). From 2003 to 2014 he became the Director of the ARC Centre of Excellence for Integrative Legume Research at UQ; after that the Centre continued until present without the central ARC funding under the new leadership of Prof. Brett Ferguson. He retired from that position in 2016, becoming an UQ Emeritus Professor.

His research focused on legume nodulation regulation, symbiotic nitrogen fixation, biofuel from Pongamia trees. He published over 480 research papers and book chapters, with over 31,000 citations, has an ‘h’ index of 88, and facilitated the development of dozens of postdoctoral fellows, over 100 PhD students, and over 90 Honours students. He is a Fellow of the AAAS, Fellow of the Russian Academy of Science, Fellow of the Indian National Academy of Agricultural Science, and twice recipient of the Alexander von Humboldt Fellowship. He was nominated for the Australia Academy of Science.

Born in 1947 in Kornelimünster, Germany, I studied biology at the University of Cologne, where I obtained a PhD in molecular genetics in 1976. I subsequently worked as a scientific assistant to Benno Müller-Hill at the Institute of Genetics in Cologne. During this period, in collaboration with Joachim Messing, I co-developed the widely used M13 cloning and sequencing phages.

In 1979, I spent six months with Robert J. Shepherd at the University of California, Davis, initiating work on cauliflower mosaic virus and achieving the first use of a recombinant plant virus to propagate foreign DNA in plants.

I later led research groups on plant viruses at the University of Cologne and the Max Planck Institute for Plant Breeding Research, pioneering the use of geminiviruses for heterologous gene expression and demonstrating for the first time that these viruses employ RNA splicing.

In 1989, I joined the newly founded Institut des Sciences Végétales, where I established a plant virology team. Our work identified tomato yellow leaf curl virus as the causal agent of a major tomato disease in the Mediterranean region and revealed unexpected evolutionary and structural conservation of replication initiator proteins among plant, animal, and human DNA viruses, supported by three-dimensional structural analyses.

She received her undergraduate and PhD degrees from the National University of México (UNAM). During her postdoctoral training she was a Visiting Scientist in BioTechnica International, Inc. in Cambridge, MA (Frank Cannon’s group) and during sabbatical leave she was a visiting scientist at the University of Minnesota – USDA, Department of Agronomy and Plant Genetics (Carroll Vance’s group) and the Max Planck Institute for Plant Molecular Physiology, Golm / Postdam Germany (Michael Udvardi’s group).

In 1983 she began her academic career at the Center for Genomic Sciences (CCG) -previously Nitrogen Fixation Research Center (CIFN)- from UNAM, in Cuernavaca, Mexico. She served as the Director of the Center from 1997 to 2005. Currently she is a Full Professor and Chair of the Eukaryotic Functional Genomics Research Program from CCG. She is member, and served as treasurer, of the Mexican Academy of Sciences.

Research from her group and collaborators, has contributed to develop the functional genomics – transcriptomics and metabolomics- of common bean, the most important legume human consumption. Using genetic, genomic and other approaches, her group investigates regulatory networks of the common bean during the N-fixing symbiosis with Rhizobium etli

Born in 1948 in Belgium, retired.
Biology studies at University of Ghent (Ugent).
With fellowships from National Fund for Scientific Research (NFWO in dutch) PhD student postdoc and research director in the lab of first Jeff Schell, then Schell-Van Montagu.
Later transfer to Ugent as full professor, Group leader “Plant Microbe Interactions” in the department of Plant Genetics of the Faculty of Sciences, later renamed department of Plant Systems Biology of VIB-Ugent.

Attila graduated as a molecular biologist at the Szeged University. He pursued his scientific degree at the Biological Research Centre of the Hungarian Academy of Sciences under the supervision of Adam Kondorosi. He spent two years as a post-doc at Institute de Biologie Moleculaire des Relations Plantes-Microrganismes, CNRS-INRA, Castanet-Tolosan, France where he participated in the construction of the first genetic map of Medicago truncatula. After returning to Szeged, he worked with György Botond Kiss and contributed to the isolation of the SYMRK gene essential for both rhizobial and mycorrhizal symboses. Then, he spent three years at the ARC Centre of Excellence for Integrative Legume Research, University of Queensland, Australia. He returned to Szeged to join as a project leader the BayGen Institute of Plant Genomics, Human Biotechnology and Bioenergy established by Eva Kondorosi. When BayGen fused with BRC, he returned to his home institute as a senior research fellow and principal investigator for a number of projects.

Leiden is Jan Kijne's hometown of science, from the start of his Biology studies at Leiden University up to and including his retirement as a professor of BioScience. After obtaining his PhD degree with the thesis "The fine structure of pea root nodules" under the supervision of Prof. dr. Anton Quispel, he got involved in teaching (microbiology, cell biology, plant physiology, philosophy of science), in research (cell biological and molecular interactions between rhizobia and leguminous plants with attachment, lectin, surface polysaccharides and pre-infection threads as a few key words) and in management (programme director of Biology, vice-dean of the Faculty of Science, co-founder and scientific director of the Leiden Pre-University College). He held consecutive professorships of Phytotechnology, Plant Physiology and BioScience, with an additional guest professorship in Microbiology at the University of Tromsø. After his retirement, he chaired the review committee of the academic Biology programmes in the Netherlands, twice.

Over the years, science absorbed more and more time at the expense of his other interests. So now, for example, he writes songs and educational booklets instead of research papers, listens to his singing granddaughters instead of work discussions, he makes food for people instead of bacteria and tries to be a family man in the first place. In Leiden, of course.

Éva Kondorosi was born in Budapest, Hungary. She obtained her degree in Biology and her PhD in Genetics from Eötvös Loránd University (Budapest). She carried out postdoctoral research at the Max Planck Institute for Plant Breeding Research (Cologne) and was a visiting scholar at the Universities of Sussex, Harvard, and Cornell.

She was a founding member of the Institut des Sciences Végétales (CNRS) in Gif-sur-Yvette, France, where she served as one of the first research directors and group leaders. Later, she became the founding director of the BAYGEN Institute in Szeged, Hungary. Currently, she is a Research Professor at the Institute of Plant Biology, HUN-REN Biological Research Centre in Szeged, Hungary where she leads research on symbiotic nitrogen fixation.

In recognition of her original scientific discoveries, she has received several prestigious awards, including the Balzan Prize, and has been elected to the Hungarian Academy of Sciences, the U.S. National Academy of Sciences, Leopoldina, Academia Europaea, the French Academy of Agriculture, and the European Academy of Microbiology. She currently serves as Chair of the Life Sciences Class of Academia Europaea, representing more than 1,700 members.

Peter Mergaert obtained his PhD in 1996 in the Laboratory of Genetics at the University of Gent, Belgium, under the supervision of Marc Van Montagu and Marcelle Holsters. After completing a post-doctoral year in the same lab, he moved to Gif-sur-Yvette in the Paris region, France, to join the lab of Adam and Eva Kondorosi at the Institute of Plant Science (ISV) for a second post-doc. In 1999, Peter was recruited by the CNRS as a researcher in Eva Kondorosi’s team, where he remained until 2013. That year, he established his own research team within the ISV. From 2014 to 2015, he was a visiting researcher at Hokkaido University, Japan, in the team of Yoshi Kikuchi. Upon returning from Japan, Peter integrated his team into the Institute of Integrative Biology of the Cell (I2BC) of CNRS and Paris-Saclay University in Gif-sur-Yvette, where they continue their research. In 2021, he founded the MICROBES interdisciplinary network at Paris-Saclay University and became its director. Since 2026, Peter has served as the director of the Microbiology Department at I2BC.

Helmi Schlaman obtained a bachelor degree in Biology and in Biochemistry at Leiden University (The Netherlands) and a Master degree in Biology with a specialisation in microbial (bacteria and viruses) - plant interactions from a molecular genetic perspective in 1987 at this same institution. In 1992 she finished a PhD with prof. dr. Ben Lugtenberg (Leiden University, The Netherlands) in the Rhizobium - leguminous plants interaction research field with a main focus on the bacterial regulatory protein NodD.

Subsequently, she held a series of postdoc positions (Leiden University, The Netherlands, and Aarhus University, Denmark) addressing mainly on the development of molecular techniques to improve visualisation of processes occurring in plants upon interaction with bacteria or other external.

In 2009 she shifted career from scientific research towards academic education. She started teaching and took up the organisation of a bachelor programme in biotechnology at Leiden University and the Technical University of Delft (The Netherlands). Since September 2023 she is retired and transmits her enthusiasm about microbiology to primary school children by giving guest lectures.

Herman P. Spaink obtained his Ph.D. (cum laude) in 1989 at Leiden University in the Faculty of Mathematics and Natural Sciences. The doctoral thesis was on molecular analysis of the Rhizobium-plant interaction (supervision Prof. Dr. E.J.J. Lugtenberg). In 1990 he started a one –year post-doc position at Harvard Medical School at the Department of Biological Chemistry and Molecular Pharmacology (supervision Prof. Dr. E. P. Kennedy). In this period, he contributed in particular to the identification of novel signal molecules produced by rhizobial bacteria that induce plant organ formation and the biochemistry of carbohydrate metabolism, in particular the discovery of important basic enzymatic functions. After a five-year fellowship at Leiden University as a researcher funded by the Royal Netherlands Academy of Arts and Sciences (KNAW) he became appointed as an assistant professor in Molecular Microbiology (1995) and subsequently as associate professor (1996) in the same department. In 1998 he was appointed as full professor in Molecular Cell Biology at Leiden University and in this function supervises cell biological teaching for the Institute of Biology of Leiden University. He has published 362 papers in refereed journals and 61 papers in books and is an author of 119 published abstracts and 28 patent applications. The H-index of his publications is 99 (source Google Scholar) and in total his work is cited over 30.000 times. His current research is mainly directed at the study of the molecular mechanisms controlling innate immune recognition using zebrafish as the main model organism with an emphasis on Toll-like receptor signaling and interactions with microbiota. This knowledge is currently applied to the study of disease models such as tuberculosis, non-tuberculous mycobacterial (NTM)-infection, diabetes and gut diseases due to microbiome aberrations.

Christian Staehelin is a Swiss scientist whose research focuses on plant–microbe interactions. He earned his PhD in 1994 from the University of Basel under the supervision of Prof. Thomas Boller. He subsequently conducted postdoctoral research in the laboratories of Prof. Eva Kondorosi and Prof. Adam Kondorosi at the CNRS in Gif-sur-Yvette, France. From 2000 to 2005, he served as Maître Assistant at the University of Geneva, Switzerland. In 2005, Dr. Staehelin was appointed Professor of Molecular Plant Biology at Sun Yat-sen University in Guangzhou, China. He is currently a Principal Investigator at the State Key Laboratory of Biocontrol and the Guangdong Provincial Key Laboratory of Plant Stress Biology at Sun Yat-sen University. Prof. Staehelin’s research team investigates root nodule symbioses in legumes with nitrogen-fixing rhizobia, as well as symbiotic interactions between plants and mycorrhizal fungi. His laboratory examines molecular signaling mechanisms during microbial infection, including the role of symbiotic glycosyl hydrolases. Additional research interests include effector proteins secreted by the rhizobial type III protein secretion system and their roles in modulating plant immune responses. Beyond molecular studies, his group has conducted ecological research on the factors governing plant–microbe coexistence and the maintenance of plant diversity. More recently, Prof. Staehelin’s team has expanded its activities into applied research, employing plant growth-promoting rhizobacteria for ecosystem restoration and sustainable agriculture.

Professor Stougaard holds a master’s degree in agronomy from University in Copenhagen and a PhD from the University of Sussex, Great Britain. As a postdoc, he joined the Department of Molecular Biology at Aarhus University, Denmark and visited the Max-Planck Institute in Cologne where Adam and Eva Kondorosi worked in the laboratory next door. At Aarhus University Stougaard´s postdoctoral research progressed into establishment of his research group focusing on interactions between plants and microorganisms. One of the early achievements was to establish the legume Lotus japonicus, a relative of Bird´s-foot trefoil, as a model organism for rhizobial symbiosis and develop genetic and genomic tools for legume research. Taking advantage of the advantageous features of this model system he identified and characterized several key genes that enable legumes to establish symbiosis with the soil bacterium Rhizobium. This opened the research field and provided fundamental discoveries and insight into the mechanisms of nitrogen fixation in legumes. Following this line of basic research, a more strategic line exploring the potential of crop biotechnology in the green transition was initiated with a focus on legume crops as a source of food and protein.

Dr. Udvardi earned his Ph.D. in plant biochemistry from the Australian National University in 1989.

He is primarily interested in how plants obtain nitrogen for growth, either as mineral nitrogen from the soil or from atmospheric di-nitrogen via symbiotic nitrogen fixation in bacteria. He has contributed to our understanding of symbiotic nitrogen fixation in legumes, especially of transport and metabolism in root nodules, using biochemical, molecular, genetic, and genomic methods. He was amongst the first to characterize ammonium and nitrate transporters in plants. He was part of a large international team that sequenced and analyzed the genome of the model legume, Medicago truncatula. Currently, his group focusses on the development of pan-genomic resources to accelerate breeding of tropical pulses, including mungbean and pigeonpea.

Dr. Udvardi has published over 200 papers in referred scientific journals. He was Elected Fellow of the American Association for Advancement of Science in 2012 for his contributions to our understanding of legume biology, especially symbiotic nitrogen fixation.

Graham C. Walker is an American Cancer Society and HHMI Professor of Biology at MIT, where he has been on the faculty since 1976. He earned his B.Sc. from Carleton University and his Ph.D. from the University of Illinois, followed by postdoctoral work with Bruce Ames at UC Berkeley, where he developed his interest in mutagenesis and DNA repair. Walker is best known for foundational work on the SOS response and mutagenic translesion synthesis (TLS), first in E. coli and later in eukaryotes, with implications for improving cancer chemotherapy. In parallel, he has made major contributions to understanding legume–rhizobium symbiosis, including discoveries involving NCR peptides, vitamin B12 biosynthesis, ribosome quality control, and the BacA transporter. Deeply committed to education, Walker has taught biology at MIT for decades, led undergraduate education programs, developed widely used educational software, and received multiple teaching honors. He is a member of the National Academy of Sciences and the American Academy of Arts and Sciences and has held numerous editorial and professional leadership roles.

B.Sc. in Molecular biology, University of Science and Technology of China, 1984; Research Assistant, Nitrogen Fixation Department, Botany Research Institute, Chinese Academy of Sciences, Beijing, China 1985; Visiting Scholar (Under the European Communities Research and Development Program in the field of Biotechnology), Genetic Department, Bielefeld University, Germany, 1986; Ph.D. in Molecular Microbiology, National University of Ireland, University College, Cork, Ireland, 1992; Postdoctoral Fellow, Molecular Biology Department, the Pasteur Institute, Paris, France, 1993; Professor in Biochemistry and Molecular Biology, School of Life Sciences, Peking University, Beijing, China, 2000-present; Vice-Dean, School of Life Sciences, Peking University, Beijing, China, 1995-2002; Senior Scientist, Yazhouwan National Laboratory, Sanya, Hainan, China, 2024-present.

At national level, acted twice as coordinator (Chief Scientist) of the “973” Development Plan of the State Key Fundamental Research on Nitrogen Fixation, 2002-2006 and 2010-2014; once as coordinator (Chief Scientist) of the National Key R&D Program of China on Nitrogen Fixation, 2020-2024. At international level, act as Member of International Steering Committee on Nitrogen Fixation 2001-present; the main organizer of the 14th International Congress on Nitrogen Fixation held in Beijing, 2004; as the instructor of the Peking University team for the International Genetically Engineered Machine Competition (iGEM), we have won the Grand Prize, 2007; Editorial Board Member with Research in Microbiology, 2015-2025; Editorial Board Member with Current Opinion in Microbiology, 2021-present.