This award honors individuals who have made an outstanding, innovative research contribution that has changed, or has the potential to change, the direction of research in any field of plant pathology.
Wenbo Ma was born in Beijing, China. She received her B.S. degree in biology from Beijing Normal University and her M.S. degree in microbial genetics from the Institute of Microbiology, Chinese Academy of Sciences. In 2003, she obtained her Ph.D. degree from the University of Waterloo, Canada. After a 3-year postdoc at the University of Toronto supported by a fellowship from the Natural Sciences and Engineering Research Council of Canada (NSERC), she was appointed as an assistant professor in the Department of Microbiology and Plant Pathology, University of California, Riverside in 2006. She was promoted to associate professor in 2012 and full professor in 2016. In July 2020, Ma relocated to The Sainsbury Laboratory (TSL) in Norwich, UK, as the first female senior group leader appointed at this premier molecular plant pathology research institution since its establishment in 1987.
Ma is internationally recognized for her outstanding contributions and innovative research on effector biology. Her research has focused on two economically important pathosystems: Phytophthora and citrus huanglongbing (HLB) diseases. Over the years, her research group has made groundbreaking discoveries on pathogen virulence strategies and plant defense mechanisms. In particular, she is one of the pioneers in establishing a role of small RNAs in plant immunity, from which the field has seen a rapid expansion in the past few years. Research in her group has substantially advanced our knowledge on the fundamental principles in plant-pathogen interactions and offered new opportunities to engineer disease resistance in crops.
The Ma group discovered Phytophthora effectors that promote disease by suppressing the host RNA-silencing process. This research is highly original as it represents the first RNA-silencing suppressors identified from a eukaryotic pathogen. Following this discovery, effectors with similar activities have been identified from other Phytophthora species and rust-causing fungi, suggesting the importance of RNA-silencing suppression as a virulence mechanism in eukaryotic filamentous pathogens. Equally important, the discovery of RNA-silencing suppression as a counter-defense mechanism provides the first indication that small RNAs contribute to plant defense against nonviral pathogens. The Ma group further characterized the host targets of these suppressors, and this line of research led to the next exciting discovery that a specific class of plant small RNAs, namely secondary short interfering RNAs (siRNAs), can silence genes in the invading Phytophthora pathogen. Independent research from other groups later demonstrated that the secondary siRNAs are enriched in extracellular space, consistent with their role as antimicrobial agents. These findings fill key conceptual gaps in our understanding of host-induced gene silencing as a natural defense mechanism. Secondary siRNA production is a deeply conserved function in land plants. Broad-spectrum and sustainable resistance may be achieved by manipulating the endogenous pathway so that the pool of siRNAs is optimized for targeting particular pathogens with increased gene-silencing efficiency. The advancement made by the Ma group has changed how we can implement small RNA-mediated immunity in agricultural practices to promote disease resistance.
A central concept in plant pathology is coevolution. Effectors are fast-evolving virulence proteins that play an essential role in manipulating plant immunity and physiology. Research in the Ma group offers important insight into the fundamental mechanisms by which effectors could evolve. They have discovered a conserved structural and functional module that is present in hundreds of Phytophthora effectors. These modules are arranged as tandem repeats and linked via a unique concatenation mechanism. This arrangement presumably facilitates effector interactions with multiple host factors and allows recombination-based unit “shuffling" that could evolve novel virulence activities. These effectors provide an excellent platform to understand effector evolution in the notorious Phytophthora pathogens and offer new insight into pathogen evolution in general.
The Ma group has also made significant contributions to the research on HLB, which has devastated the citrus industry worldwide. Despite substantial efforts, mechanistic insights into the virulence activities of the HLB-associated bacterium Candidatus Liberibacter asiaticus remain largely unknown. The Ma group takes a systems approach to characterize Ca. Liberibacter asiaticus Sec-delivered effectors (SDEs). They found effector SDE1 inhibits the enzymatic activity of papain-like cysteine proteases in citrus and promotes bacterial infection. This milestone work represents the first effector-triggered susceptibility mechanism described in HLB. Another major challenge in HLB is diagnosis. The Ma group has pioneered the development of antibody-based detection methods using SDEs as markers. This innovation may facilitate HLB diagnosis and improve management of this devastating disease.
In summary, Ma has maintained a highly productive research program, and has always aimed to link basic research with applied plant pathology. Her research is innovative and influential, as reflected by 34 publications in high-impact journals (Cell Host & Microbe, Nature Plants, Nature Structure & Molecular Biology, Nature Communications, PNAS, etc.), 16 invited reviews and book chapters, and 78 invited talks. Ma is the primary inventor of three patents and patent applications, demonstrating the potential of her research findings in real-world applications. She received the APS Schroth Face of the Future Award in 2012.
In addition to her outstanding research accomplishments, Ma has been actively involved in professional service to APS and the general plant pathology research community. She was an associate editor for Phytopathology (3 years) and a senior editor for Molecular Plant-Microbe Interactions (3 years) and is currently a section editor of PLoS Pathogens (since 2015) and an associate editor of New Phytologist (since 2018). She has served on several federal grant panels and was a member of the APS task force committee for the 2020 International Year of Plant Health.
For her groundbreaking research, as well as her service to the plant pathology community and APS, Wenbo Ma is highly deserving of the Ruth Allen award.