Barbara S. Valent was born in Perry, Iowa and grew up in Colorado. She studied at the University of Colorado at Boulder, earned a B.A. degree in chemistry in 1972, a Ph.D. degree in biochemistry in 1978, then conducted postdoctoral work at Cornell University and the University of Colorado. In 1985 she joined DuPont Central Research and Development as a principal investigator in molecular plant pathology. She was promoted to research leader in 1992 and research manager of the Plant and Fungal Genetics and Molecular Biology Program in 1994. Valent became research fellow and technical leader of the Genetic Disease Resistance Program in DuPont Agricultural Products in 1997. Valent joined the Department of Plant Pathology at Kansas State University in 2001 as a Professor and was recognized as a University Distinguished Professor in 2002. In 2007, she was named a Fellow of the American Phytopathological Society and of the American Association for the Advancement of Science.
Since being named APS Fellow in 2007, Valent has made seminal contributions to our understanding of fungal infection of plants and effector delivery and function in host cells in agronomic crops and pathogens of global significance. Valent’s creative approach to studying host-pathogen interactions has led to great strides towards understanding and controlling these diseases, and they have become models for advancing the study of other pathosystems. Her research is recognized as ground-breaking and she was recognized as a “Top Author” by the American Society of Plant Biologists, based on publication of highly cited papers in The Plant Cell from 2009 to 2013 (Mosquera et al, 2009, Yi et al, 2009; Khang et al, 2010; Park et al, 2012).
Since 2007, Valent’s work studying rice blast disease caused by the Magnaporthe oryzae Oryzae pathotype has revealed strategies of fungal invasion of plants and movement of effectors out of the fungus and into the plant. Valent and colleagues described the formation of a specialized structure that forms during the biotrophic infection stage (Mosquera et al, 2009; Khang et al, 2010). They named this novel structure the biotrophic interfacial complex (BIC) and used fluorescent-protein tags fused to putative effector proteins to demonstrate that cytoplasmic effectors (those that are delivered inside living host cells) were targeted to BICs before translocation inside the plant cells. In contrast, extracellular effectors did not localize to BICs. Valent’s approach was unique, using live cell imaging to visualize fungal invasion non-destructively. This was the first definitive demonstration of delivery of effectors into the plant cell cytoplasm for any filamentous plant pathogen (fungi or oomycetes) (Khang et al, 2010). Valent also demonstrated that M. oryzae exploits the plant plasmodesmata during the invasion process, detecting two effectors (Pwl2 and Bas1) up to four plant cells away from the fungus (Khang et al, 2010; Sakulkoo et al, 2018). Previously, plasmodesmata were thought to only be relevant for plant virus movement. Valent’s laboratory led the way in discovering that the fungus uses a specialized (golgi-independent) secretion system for locating cytoplasmic effectors in BICs, while using the conventional system to secrete the extracellular effectors (Giraldo et al, 2013). This was the first example of novel effector secretion system in a filamentous plant pathogen. The novel effector secretion system in M. oryzae externalizes effectors directly from the ER, bypassing Golgi, and involves the exocyst complex (Yi et al, 2009; Giraldo et al, 2013; Zhang et al 2016). Others have used Valent’s approaches to probe other plant-pathogen interactions, revealing commonalities in effector biology.
Since 2009, Dr. Valent has become a world leader in research on wheat blast, caused by the Triticum pathotype of M. oryzae. Wheat blast has caused significant crop damage in South America since 1985 and was recently found in Bangladesh. Valent leads an interdisciplinary team of research and extension specialists from diverse institutions in the U.S. and South America focused on improving blast control in U.S. rice production and preparing to block potential introduction of blast into the U.S. wheat crop. The research is performed in Biosafety Level-3 laboratories in the U.S. and in the field in Bolivia, Brazil and Paraguay. Project members are studying the field disease biology and host specificity of the pathogen, identifying resistance, and developing diagnostics, forecasting models and training resources while exploring the molecular biology of the system. They determined the major source of head blast resistance in wheat is confined to the 2NS translocation locus, a substantial breakthrough in understanding heritability of resistance and the mechanism of virulence (Cruz et al, 2015 and 2016). Understanding the relatedness of the host-adapted populations (pathotypes) of M. oryzae and their evolutionary potential has been greatly advanced by the molecular work, especially using phylogenomics, that has been conducted by Valent and her colleagues (Malaker et al, 2016; Farman et al, 2017; Inoue et al, 2017; Pieck et al, 2017; Gladieux et al, 2018). Valent plays a significant leadership role in the national and international response to this emerging disease. She participated in the 1st International Wheat Blast Workshop (Brazil, 2010); became a founding member of the International Wheat Blast Consortium; and served as vice-chair for the 2nd International Workshop on Wheat Blast (Brazil, 2016).
Valent is also a dedicated mentor and teacher and she has mentored 6 graduate students, 15 post-doctoral fellows, 10 undergraduates and 4 exchange students (from Korea, Germany, Colombia, China). In 2010 she was selected by the graduate students of the KSU Department of Plant Pathology as the first recipient of their new Mentor Award. She is recognized for her teaching excellence, and she teaches graduate courses on Molecular Plant Microbe Interactions, Fungal Genetics, and Resistance to Plant Disease.
Valent is an innovative scientist and inspiring leader in the field of molecular plant-microbe interactions. Her detailed, creative work on the dynamics of the molecular mechanisms of M. oryzae pathogenicity has provided insight that has been translated to other pathogen-host interactions and for control of plant diseases.