Pierre J. G. M. de Wit was born on February 27, 1949, in Grathem, the Netherlands. He received his M.Sc. degree in plant pathology from Wageningen University (WU), the Netherlands, in 1974. During his M.Sc. studies, he became fascinated by the genetics of innate immunity in plants as hypothesized in the gene-for-gene model pioneered by the American and Dutch scientists Flor and Oort, respectively. This fascination in innate immunity of plants remained throughout his career. In 1981, he received his Ph.D. degree from WU for work focused on cultivar-specific resistance of tomato to the fungal pathogen Cladosporium fulvum. In that system, he found support for the existence of both nonspecific elicitors, components that we nowadays call pathogen-associated molecular patterns (PAMPs). Later, he found evidence for the existence of specific elicitors, communicated in a 1982 seminal publication in Physiological Plant Pathology entitled “Evidence for the occurrence of race and cultivar-specific elicitors of necrosis in intercellular fluids of compatible interactions of C. fulvum and tomato.” He spent a sabbatical year on a Fulbright fellowship in the laboratory of J. A. Kuc at the University of Kentucky, Lexington. He returned to the Netherlands and was appointed assistant professor of plant pathology at WU in 1982 and was promoted to associate professor in 1986 and to full professor in 1990. Since 1992, he has served as head of the Laboratory of Phytopathology at WU. From 1999 to 2004, he served as director of the multi-institutional Graduate School “Experimental Plant Sciences” of the Netherlands. Since 2003, he has also served as scientific director of the Centre for Biosystems Genomics, a Dutch center of excellence in plant and microbial genomics.
de Wit has made several outstanding contributions to molecular plant pathology, which are described in more than 120 original articles and reviews. Among his major accomplishments is the cloning and characterization of the first fungal avirulence gene, Avr9, in 1991. This momentous discovery was closely followed by the identification in his research group of a second avirulence gene, Avr4, described in a 1994 publication in Nature. This pioneering work was the first demonstration that fungal resistance is mediated by recognition of peptides and has greatly influenced many scientists working on host specificity and disease resistance, resulting, for instance, in the cloning of one of the first fungal plant resistance genes. The availability of the Avr9 gene was instrumental for cloning the Cf-9 resistance gene of tomato by a longtime collaborator, Jonathan Jones. In addition, the topic of fungal avirulence remains particularly current. More than a dozen years after the identification of Avr9, avirulence genes have been recently identified for the first time in obligate biotrophic fungi and oomycetes. It is now well accepted that understanding the virulence function of effector proteins is central to a mechanistic understanding of pathogenicity not just in interactions of plants with fungi but also with bacteria, oomycetes, and nematodes.
Presently, de Wit’s research group has cloned eight effectors of C. fulvum and to all of them cognate Cf genes do exist in wild accessions of Solanum species. Resistance breeding using Cf genes has shown to be a very powerful and sustainable strategy to combat the leaf mold pathogen. He expanded his work on Avr4 and Avr9 and further exploited the C. fulvum–tomato system to make groundbreaking contributions to our understanding of race evolution in fungi by describing four different mechanisms by which they can evade recognition of the avirulence peptides by its host. He also characterized the virulence functions of two Avr peptides. In a 2005 Science publication, he showed, in collaboration with Jones’s group, that the Avr2 peptide is secreted by C. fulvum into the apoplast of tomato and triggers cell death only in the presence of the tomato extracellular protein Cf-2 and the cysteine protease Rcr3. Avr2 binds and inhibits Rcr3, and the Rcr3–Avr2 complex is subsequently recognized by the Cf-2 protein, illustrating the dual functions of fungal avirulence proteins. In a few other key publications in the Journal of Biological Chemistry and Molecular Plant-Microbe Interactions, he showed that Avr4 is a chitin-binding protein that protects the fungus against plant chitinases. Avr4 proteins encoded by virulent alleles are no longer recognized by Cf-4 plants but still bind chitin, suggesting that chitin binding represents a virulence function. His research group also made significant contributions to understanding signal transduction responses triggered by Avr peptides and mediated by cognate Cf proteins in plants, including an NB-LRR protein required for not only Cf-4-mediated hypersensitive response but also R genes against other pathogens. His findings have lead to several patents to exploit Avr-R gene interactions and defense signaling genes in disease resistance breeding.
de Wit has taken several leadership roles to service the science of molecular plant pathology. He is the current president of IS-MPMI, and in 1999, he organized the international congress of the society in Amsterdam. Also, he organized several EU workshops, chaired the Scientific Committee of the 1995 Fungal Genetics Conference, and vice-chaired the Scientific Committee of the 1998 ICPP Congress. He is highly committed to training the next generation of scientists. As the head of the Laboratory of Phytopathology, he oversees a very active and diverse group of plant pathologists. In total, he supervised 40 Ph.D. students, several of which went on to become active scientists on their own. He teaches both introductory and advanced plant pathology courses. His teaching skills are in high demand, and he was invited to contribute to about a dozen Ph.D. national and international summer schools and courses.
de Wit is a regular keynote and session speaker at major conferences. Over the years, he has offered more than 125 invited seminars and presentations at various institutions and international conferences, including IC-MPMI, ICPP, ICCP, IC-PMB, Keystone Symposia, and the Gordon Conferences. He is recognized as a highly cited scientist in his discipline. He has served on the editorial board of several journals and in the advisory board of companies and institutions, such as Monsanto, Zeneca/Mogen, Scottish Research Institute, and the Max-Planck Institutes for Molecular Breeding and Terrestrial Microbiology, respectively. He received several awards for his research accomplishments, notably the Emil Christian Hansen Gold Medal for outstanding contributions to research in microbiology by the Carlsberg Foundation, Copenhagen, and the research prize of WU. In 1991, he was elected as a member of the Dutch Society for the Advancement of Science and, in 1999, of the Royal Netherlands Academy of Arts and Sciences.