Barbara S. Valent
Barbara S. Valent was born in Perry, IA, and grew up in Colorado. She received her B.A. degree in chemistry in 1972 and her Ph.D. degree in biochemistry in 1978 from the University of Colorado at Boulder. Following postdoctoral work at Cornell University and the University of Colorado, she began her research career as a principal investigator in molecular plant pathology at DuPont Central Research and Development, Delaware, in 1985. She was promoted to the ranks of research leader in 1992, research manager of the Plant and Fungal Genetics and Molecular Biology Program in 1994, and research fellow and technical leader of the Genetic Disease Resistance Program of DuPont Agricultural Products in 1997. Valent was appointed as a professor in the Department of Plant Pathology at Kansas State University (KSU) in 2001. In 2002, she was designated a university distinguished professor, and in 2004, she was appointed chair of the Interdepartmental Genetics Program at KSU.
Valent has made outstanding and fundamental contributions in the field of plant pathology. More than 20 years ago, Valent recognized the need for a well-characterized and easily manipulated model system to understand how plants and fungi interact to ultimately lead to disease or resistance. She proposed and developed Magnaporthe grisea, the rice blast fungus, to serve as such a model. Due to her efforts, this pathogen is now one of the most extensively studied and important fungal models for molecular genetic and biochemical analyses of plant–fungal interactions. Using this research tool as her base, she has been at the forefront of several fundamental areas. Valent was the first to identify and clone both a blast fungal gene that controls the induction of resistance in plants (Avr gene) as well as the corresponding gene from rice (R gene) that is involved in recognition of the fungal gene. She was the first to demonstrate for this class of R gene that the AVR and R gene products physically interact and that this interaction likely occurs inside living plant cells. These are exciting findings with huge implications for the transduction of the signals resulting in plant resistance.
Valent has been an effective champion for fungal genomics, serving on the scientific advisory board for the M. grisea genome sequencing project since the effort was funded by NSF. Since joining the KSU faculty, she has been a leader and an active participant in the land-grant universities' multistate research committee focused on Biochemistry and Genetics of Plant-Fungus Interactions (NCR173). Interesting new research is coming out of the opportunity for contrasting and comparing the lifestyles of different fungi studied by the project's participants.
Valent is continuing to make fundamental advances in the field of plant pathology. Currently, she is applying functional genomics and advanced cell biology techniques to analyze the earliest events in plant–fungus interactions. Using live cell fluorescence microscopy, she and her students have discovered that, at any given infection site, the rice blast fungus sequentially invades plant cells through a process that appears to be exclusively biotrophic. This is a surprising result, because the fungus was previously thought to switch to a necrotrophic style of infection soon after penetrating the first plant cell. Moreover, Valent and her students have found that the process through which the fungus moves from cell to cell within the plant involves extreme hyphal constriction and appears to rely on movement through plasmodesmata, the tiny channels that connect one plant cell to another. Both of these results were reported in an invited lecture that Valent presented at the 2006 International Plasmodesmata Conference in Scotland.
Using laser microdissection and other novel enrichment techniques, she and her students are analyzing plant and fungal gene expression in the first-invaded plant cells. A number of fungal genes have been identified that show a hundreds-fold increase in expression upon plant infection, and these genes are being further analyzed via functional genomics approaches, including bioinformatics and gene disruption. These genes are good candidates for fungal effectors of pathogenicity, a topic that is currently poorly understood in plant-pathogenic fungi.
Valent's many profound insights also have important practical applications. While elucidating how fungal pathogens adhere to and penetrate host plants, which involved the genetic dissection of melanin biosynthesis in M. grisea, she and her colleagues discovered different possible targets for chemical control of fungal diseases and also a powerful fungal adhesive that even sticks to Teflon! This adhesive was later patented. Based on findings using molecular markers for analysis of M. grisea population structure over wide geographic areas, she and her collaborators have fundamentally changed the strategies plant breeders use to deploy resistance to this important disease. Molecular markers corresponding to the R gene cloned in her laboratory have also been valuable, because this gene confers resistance to the major pathotypes of the fungus in the United States. Thus, Valent's basic research has had huge implications for practical disease control.