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2022 Fellow Dr. Steven Whitham​

The society grants this honor to a current APS member in recognition of distinguished contributions to plant pathology or to The American Phytopathological Society. Fellow recognition is based on significant contributions in one or more of the following areas: original research, teaching, administration, professional and public service, and/or extension and outreach.

Steven Whitham was born in Fairfield, IA, and attended Pekin Community Schools. He earned a B.S. degree in agricultural biochemistry from Iowa State University in 1990 and a Ph.D. degree in plant pathology from the University of California, Berkeley, in 1995, where he cloned the “N” gene for resistance to Tobacco mosaic virus (TMV) with Barbara Baker. This landmark discovery established N as the first cloned viral resistance gene and founding member of the Toll/Interleukin-1-receptor nucleotide-binding leucine-rich-repeat (TIR-NLR) class of resistance proteins. It is noteworthy that this discovery preceded the Nobel Prize-winning work of Jules Hoffman that demonstrated Toll-like receptors also function in animal immunity. Whitham and Baker then collaborated with Sheila McCormick at the USDA-Plant Gene Expression Center to show that N-specified TMV resistance could be transferred to transgenic tomato, one of the first demonstrations that NLR proteins confer disease resistance across species. As a postdoc from 1996 to 1999 at Texas A&M and Washington State University with Jim Carrington, he established that marker protein-tagged viruses enable novel large-scale screens for loss of resistance or loss of susceptibility.

He applied this technology to clone RTM (RESTRICTED TEV MOVEMENT) genes that function cooperatively in Arabidopsis thaliana and to identify translation initiation factor eIF(iso)4E as an essential host factor for potyvirus infection. This discovery first established translation factors as crucial for infection and was subsequently validated for a diverse range of viruses by many labs and breeders. Following his postdoc, Whitham moved to the Torrey Mesa Research Institute in San Diego, where he was a leader in applying the new technology of global gene expression profiling to host-virus and, more broadly, host-pathogen interactions. This experience laid the groundwork for his research as a professor in plant pathology and microbiology (PLPM) at Iowa State University (ISU), starting in 2000. In addition to his work on resistance genes, Whitham has been a trailblazer in host response to viruses in compatible interactions. In 2003, he was the first to apply genome-wide Affymetrix GeneChip technology (state-of-the art prior to next-gen sequencing technologies) to Arabidopsis-virus interactions, where he discovered a core response to diverse RNA viruses typified by induction of defense-related and heat shock genes and downregulation of genes related to photosynthesis. He led his group to show that compatible viruses activate defense-related genes via a salicylic acid-dependent signaling pathway and, recognizing a shortcoming of most gene expression experiments in whole leaves, demonstrated the power of using a GFP-tagged virus for spatial and temporal expression profiling at millimeter resolution, resulting in more refined models of Arabidopsis gene expression to compatible viruses. Particularly interesting was the observation that viruses can upregulate most of the plant ribosomal proteins, likely enhancing viral protein synthesis. He then identified key ribosomal proteins in potyvirus replication. Parallel phenomena occur in mammalian virology, revealing the broad applicability of Whitham’s discoveries.

As a testament to his versatility, Whitham turned his attention to Asian soybean rust (Phakopsora pachyrhizi), a major threat to U.S. soybean production upon its arrival from South America in the early 2000s. Whitham and ISU associate Thomas Baum initiated a strategic collaboration and training program with colleagues from Brazil, Germany, and USDA-ARS to identify innate resistance genes, genetic pathways regulating immunity, candidate effectors by haustorial RNA-sequencing and characterized effectors in soybean-P. pachyrhizi interactions. These studies have not only provided valuable information on soybean rust, but they have been broadly informative to the rust research community, including novel approaches for large-scale screening of rust effector candidates and suppression of plant immunity. Whitham has been a leader in engineering viruses for accelerating plant functional genomics studies and understanding host-virus interactions. In collaboration with ISU colleague John Hill, he developed virus-induced gene silencing (VIGS) and virus overexpression (VOX) vectors from Bean pod mottle virus, Foxtail mosaic virus, and Sugarcane mosaic virus for use in diverse and important crops, such as maize and soybean, and silenced >200 genes to test their functions as positive or negative regulators of soybean defense.

Most recently, in collaboration with Dan Voytas’ group at University of Minnesota, he showed that viruses can be used to speed-up CRISPR/Cas gene editing in monocots. Foxtail mosaic virus engineered to express single guide RNAs caused site-specific mutations in Setaria viridis (green foxtail) and maize plants expressing the Cas9 protein. These approaches accelerate development of genome engineering technologies. Whitham has also been a leader in robotic imaging and image analysis for high-throughput plant phenotyping, with a goal of applying such approaches to phytopathology. He led an interdisciplinary NSF-funded team of plant biologists, engineers, and bioinformaticists to build the unique Enviratron automated plant phenotyping facility at ISU, enabling studies to be conducted under up to eight, highly controlled environmental conditions in a single time-course experiment with RGB, hyperspectral, thermal, fluorescence, and 3D images.

Whitham’s contributions to plant pathology include discoveries that significantly expand the state of the science, as well as enabling tools and resources that drive advances across and outside the field. He has received numerous awards from ISU, as well as being elected a Fellow of AAAS in 2016. He’s a highly valued instructor who is central to teaching both core and advanced virology and plant-pathogen interaction courses in the microbiology and plant pathology graduate programs. In his 21 years in APS, Whitham served as an associate and senior editor for Molecular Plant-Microbe Interactions, a senior editor for Molecular Plant Pathology, and, currently, an editor for PhytoFrontiers. As PI or co-PI, he has garnered over $24 million in federal, commodity, and industry funding; received 70 invitations to speak at universities, regional, national, and international symposia; and authored over 80 publications in high-impact journals that have been cited over 10,000 times. He has engaged and trained the next generation of scientists from diverse backgrounds toward their careers in STEM. As a result, more than 50 undergraduate, graduate, and postdoctoral scientists now play important roles at universities/international institutes, government agencies, biotech companies, hospitals, HBCUs, and K-12 schools on four continents, advancing the land-grant mission of sharing knowledge among populations around the world.