Jonathan Walton received his B.A. degree in biology from the University of California, Santa Cruz. He received his master’s degree in plant pathology from Cornell University, working with Olen Yoder, Elizabeth Earle, and Roger Spanswick on the mode of action of T-toxin from Cochliobolus heterostrophus (Helminthosporium maydis), and his Ph.D. degree from Stanford University in 1982. He then returned to Cornell to work with Elizabeth Earle on the structures and modes of action of host-selective toxins, including HC-toxin and victorin from C. carbonum and C. victoriae, respectively. After a year at the University of Rome, working with Alessandro Ballio on fusicoccin receptors, he took a position at the former ARCO Plant Cell Research Institute (Dublin, California), where he began to study the enzymology of HC-toxin biosynthesis. In 1987, he moved to the Department of Energy (DOE)-Plant Research Laboratory and the Department of Plant Biology at Michigan State University (MSU). Here, he continued his studies on the maize–C. carbonum system and the HC-toxin.
Walton’s program has lead to the molecular characterization of the genetic locus (TOX2) controlling HC-toxin production, including one of the first characterizations of a gene for a multidomain nonribosomal peptide synthetase. Related studies in his lab (in collaboration with Guri Johal and Steve Briggs, then at Pioneer Hi-Bred International) demonstrated that the Hm1 resistance gene in maize encodes an enzyme that detoxifies HC-toxin. This was the first disease resistance mechanism that had ever been identified, and the ensuing publications were landmarks in this important area of plant research. Furthermore, his lab (in collaboration with Peter Loidl and coworkers at the University of Innsbruck) identified histone deacetylase as the site of action of HC-toxin. This exciting discovery directly links pathogenesis with interference in host gene regulation. Thus, Walton’s discoveries provide an extraordinarily comprehensive understanding of a pathosystem, including the chemical structure, the pathway of synthesis, the mode of action of the pathotoxin, and the biochemical basis for genetic resistance against it.
Interestingly, Walton and coworkers recently showed that the cyclic peptide toxins of poisonous Amanita mushrooms are synthesized on ribosomes and not, like HC-toxin and other fungal cyclic peptides, by nonribosomal peptide synthetases.
Walton has also made contributions to our understanding of the role of cell-wall-degrading enzymes in virulence, including identification of SNF1 as a regulator of enzyme expression and virulence in plant-pathogenic fungi. Using modern tools of proteomics, he demonstrated the feasibility of detecting numerous fungal proteins in infected plant tissue, many of which are degradative enzymes. His work in this area led to his current interest in the application of cell-wall-degrading enzymes to the deconstruction of lignocellulosic materials for bioenergy production. As a world authority in this area, Walton has recently been appointed associate director of the DOE-funded Great Lakes Bioenergy Research Center at MSU.
Walton has been a dedicated teacher of undergraduate students. He is passionate about teaching junior scientists the thrill of conducting scientific research, demonstrating his enthusiasm by working alongside them at the bench and setting a personal example of experimental rigor and creativity. He has trained a large number of graduate students and postdoctoral research associates, many of whom have moved on to productive careers of their own, as well as undergraduate students who performed their senior research projects in his laboratory.
Walton has served as editor-in-chief of the newsletter of the International Society for Plant-Microbe Interactions (IS-MPMI Reporter), on the board of directors of IS-MPMI, and as president of IS-MPMI (2003–2005). He has been a senior editor of Molecular Plant-Microbe Interactions and is currently the editor-in-chief of MPMI, in which role he also serves on the APS Publications Board. He has also served on the editorial boards of the Annual Review of Phytopathology and Eukaryotic Cell. In 2002, he received the MSU Distinguished Faculty Award.