Sophien Kamoun was born on December 8, 1965, in Tunis, Tunisia. He received his Maitrise (B.S.) degree from Pierre and Marie Curie University, Paris, France, in 1987. He then attended the University of California-Davis, where he received his Ph.D. degree in genetics in 1991 while conducting his doctoral research in the Department of Plant Pathology. He then served as a post-doctoral fellow at the University of California-Davis Center for Engineering Plants for Resistance Against Pathogens (CEPRAP), a NSF Science and Technology Center, and as a senior research scientist in the Department of Phytopathology, Wageningen University, the Netherlands. In 1998, Kamoun was appointed assistant professor of oomycete molecular genetics at The Ohio State University, Department of Plant Pathology, Wooster campus, and was promoted to associate professor in 2002 and professor in 2006. In 2007, he joined The Sainsbury Laboratory, Norwich, United Kingdom, where he is currently senior scientist and head. He also holds a professor of biology chair at The University of East Anglia, Norwich, United Kingdom.
Kamoun is a pioneer and leader in the modern fields of effector biology and genomics of eukaryotic plant pathogens, publishing the first and most influential papers on these topics. His research has centered on the Irish potato famine organism Phytophthora infestans, a pathogen of great historical significance that continues to threaten subsistence and commercial potato production worldwide. Phytophthora and other oomycete plant pathogens have long been considered intractable organisms for molecular genetics research. His contributions have been critical in addressing this issue and shifting the focus in the study of oomycetes to the investigation of pathogenicity mechanisms.
Kamoun pioneered the use of functional genomics strategies that link plant pathogen sequences to phenotypes and is credited with discovering several disease effector families from pathogenic oomycetes. In the early 2000s, his group, then at The Ohio State University, designed and implemented algorithms to identify effector genes from sequence data. He developed this approach with his first Ph.D. student, Trudy Torto, and their 2003 publication described the first bona fide effector family from oomycetes. His team later demonstrated that these effectors, known as Crinkler (CRN) proteins, are modular proteins with predicted secretion signals and conserved N-terminal sequence motifs that mediate transport inside plant cells. Inside plant cells, this large family of ubiquitous oomycete effector proteins targets the host nucleus to modulate plant immunity.
Kamoun used the functional genomics pipelines he developed to discover additional families of effector proteins. With Miaoying Tian, another Ph.D. student, he published the first report of a protease inhibitor in any plant-associated microbe. He followed with several studies that confirmed that these effectors inhibit various host defense proteases in the plant apoplast. Since then, protease inhibitors have been reported in several other plant pathogens, suggesting a general counter defense mechanism. Also, with Ph.D. student Jing Song, Kamoun was the first to demonstrate that unrelated plant pathogens from different kingdoms have evolved to deploy effectors (protease inhibitors) to target the same host defense protein. This concept has since been generalized to other plant–pathogen interactions.
Kamoun was one of the key scientists directly involved in the discovery of the RXLR host translocation motif of oomycete effectors. He and his collaborators then demonstrated that the RXLR domain functions in the human parasite Plasmodium, suggesting a similar mechanism of host translocation in plant and animal eukaryotic pathogens.
With British collaborators, Kamoun also discovered the RXLR-type effector AVR3a, the first P. infestans avirulence effector. With Ph.D. student Jorunn Bos, he followed up with several seminal papers that established that AVR3a suppresses plant immunity and that it does so by binding and stabilizing the host E3 ubiquitin ligase CMPG1. Kamoun published the first report of a cell death suppressor from a eukaryotic plant pathogen and CMPG1 is the first target protein reported for a host-translocated oomycete effector. More recently, he continued to establish a mechanistic understanding of how oomycete effectors modulate plant immunity, showing among other findings that the RXLR-type effector AVRblb2 focally accumulates inside plant cells and promotes virulence by interfering with polarized secretion of an immune protease.
Kamoun is a recognized leader in the field of plant pathogenomics. In 1999, he published the first cDNA sequencing project for a plant pathogen and was a key member of the Syngenta Phytophthora Genomics Consortium (1998–2002). He has taken a leading role in community efforts to obtain genome sequences of oomycetes, particularly P. infestans, which was published in Nature in 2009. This and follow-up work revealed that the P. infestans genome experienced a dramatic repeat-driven expansion and has a highly unusual “two-speed” genome architecture that underpins adaptability to host plants. Kamoun and his lab members also contributed to several genome sequencing projects of oomycete pathogens, such as Phytophthora sojae, Phytophthora ramorum, Pythium ultimum, and the Arabidopsis downy mildew.
Kamoun made key contributions to understanding how antagonistic coevolution with host plants impacts pathogen genomes. He demonstrated that following host jumps and during host specialization of a plant pathogen, highly dynamic genome compartments, enriched in genes involved in pathogenicity and epigenetic maintenance, underpin accelerated gene evolution and host adaptation. Gene-sparse, repeat-rich regions that define the extremely uneven architecture of the P. infestans genome are highly enriched in plant-induced genes, particularly effectors, highlighting host adaptation as a driving force of genome evolution in this pathogen lineage.
Sophien Kamoun significantly contributed to the theoretical development of the plant–microbe interactions field through a number of highly cited influential reviews. He was one of the first to popularize and extend the concept of effectors to eukaryotic pathogens. With Renier van der Hoorn, he developed the decoy model of effector recognition by plant immune receptors. Kamoun’s work on oomycete effector biology and pathogenomics has also resulted in new approaches to breeding disease-resistant crops. Traditionally, resistance genes have been identified, bred, and deployed in agriculture without detailed knowledge of the effectors they are sensing—a “blind” approach. With Dutch collaborators, particularly Vivianne Vleeshouwers, Kamoun pioneered the use of effector screens (effectoromics) to identify and profile the activities of plant disease resistance genes; this enables breeders or genetic engineers to be more efficient and avoid deploying multiple resistance genes that recognize the same effector.