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Krishna V. Subbarao

Krishna V. Subbarao

Krishna V. Subbarao was born in 1958 in Periyapatna, Mysore District, Karnataka.  He obtained his B.S. from Yuvaraja’s College, Mysore and M.S. in Plant Pathology from Manasagangothri, University of Mysore, and Ph.D. in Plant Pathology in 1989 from Louisiana State University, Baton Rouge, USA. Dr. Subbarao then took up postdoctoral researcher positions at Louisiana State University and University of California at Berkeley prior to joining the faculty of the Department of Plant Pathology in 1992 at the University of California at Davis, where he is currently a full professor.

Prof. Subbarao’s career research achievements have come from the study of two fungal pathogens, Sclerotinia spp. and Verticillium spp. He utilized these systems for his pioneering research addressing some of the most complex and persistent questions in these two systems.  Prof. Subbarao developed a highly innovative, yet very practical, knowledge base of soilborne disease management including quantitative models to minimize inoculum and disease dynamics between seasons and elucidated mechanisms of soil suppressiveness.  The framework developed has become the standard approach for managing diseases caused by these two pathogens worldwide.

Prof. Subbarao’s group elucidated the fastidious environmental conditions for ascospore production and the reasons for differential distribution of S. sclerotiorum and S. minor in the world. This meticulous work over two decades has provided a lucid understanding of the unique niches occupied by the Sclerotinia species.  His group has also characterized the process by which ascospore production and maturity of S. sclerotiorum is synchronized, providing new insights into the reproductive biology of this pathogen.  Finally, the results from the study of the mating type locus of S. sclerotiorum were unexpected and exciting.  They showed that parts of the mating type locus MAT in S. sclerotiorum was inverted in exactly half of all sexual progeny, independent of whether the inversion was present in the parent.  This original discovery may underlay the process of mating type switching in filamentous ascomycetes for which no molecular bases have been known.

Prof. Subbarao is perhaps best known for his seminal studies on Verticillium wilt caused by Verticillium dahliae and other Verticillium spp.  V. dahliae is a pathogen of great genetic plasticity, can infect more than 200 plant species and the list of potential hosts is continually expanding. Employing molecular phylogeny, his group resolved the longstanding taxonomic problems in the genus Verticillium and it also led to the discovery of five species new to science. In recent years, he has focused on the population genetic analyses of a global population of V. dahliae that identified northern Europe as the source population for all V. dahliae in the world.  Prof. Subbarao in a series of well-conceived studies, determined that broccoli cultivation not only significantly reduced soil inoculum, but also wilt incidence and severity in subsequent susceptible crops. Unlike soil fumigation, rotations with broccoli do not eradicate the pathogen, but maintain soil microsclerotia below the threshold at which crop losses accrue, despite the cultivation of susceptible crops.  He obtained empirical data on the mechanisms of broccoli-induced V. dahliae suppression using a combination of soil microbiology, soil chemistry, and molecular cytology.  He demonstrated that not all glucosinolates and their catabolic products are involved in pathogen suppression and that V. dahliae suppression by broccoli involves multiple factors (e.g., the type of glucosinolates and their catabolic products, soil microbial community communities). This interdisciplinary work lays the knowledge foundation for an economically feasible disease management practice in this and other pathosystems.

Prof. Subbarao possesses a prolific publication record with over 180 refereed journal articles in addition to the many reviews and book chapters he has published.  He is currently editing the Lettuce Compendium published by the APS Press.  He has also overseen the research of staff, undergraduates, graduate students working toward the Ph.D. degree, and 22 postdocs from diverse cultural backgrounds.  His former associates are pathologists in government and academia, with six being faculty in land grant universities in the USA.  Prof. Subbarao is currently the Editor-in-Chief of Phytopathology, previously served two terms as a Senior Editor and also a term as an Associate Editor in Phytopathology.