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2021 APS Fellow​

​​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.

Cindy Morris was born in South Bend, IN, and obtained her B.S. degree at Michigan State University in 1979. After obtaining her Ph.D. degree in plant pathology from the University of Wisconsin–Madison in 1985, she worked as a postdoctoral researcher until 1989 in the Laboratory of Phytobacteriology of the Department of Plant Protection at Beijing Agricultural University, People's Republic of China. She has since been employed as a research scientist in the Plant Pathology Research Unit in INRAE-PACA, in Avignon, France, where she serves as research director.

Morris is a highly innovative researcher who has challenged and developed new paradigms in plant pathology through her studies of Pseudomonas syringae. She has revolutionized the way we look at many such plant-pathogenic bacteria through her work, which has shown that species such as P. syringae have marked saprophytic phases that are not necessarily associated with living plant tissues. It has been through such an understanding of the population genetics of bacterial species we call plant pathogens that she has been able to demonstrate that it is possible to anticipate disease outbreaks or emergence from environmental reservoirs of such species as saprophytes in various settings or pathogens on other hosts. The ability to predict epidemics remains one of the major issues facing the field of plant pathology, and it is through the work of Morris that we can now more effectively anticipate and monitor the natural world to be prepared for the emergence of new pathogens rather than simply reacting to them. She has shown that P. syringae is widely distributed in the natural environment outside of cropping systems and that its diversity in these other settings is much greater than agricultural habitats. Furthermore, she has demonstrated that its life history is linked to the water cycle and that many nonagricultural habitats are reservoirs of this pathogen and are havens for its genetic diversification. Central to these findings has been her demonstration that many strains of P. syringae are highly active in ice nucleation and are a major, necessary component of atmospheric precipitation processes, seeding ice particles that are required for rain or snow formation that serves to remove it from the atmosphere and deposit it on plants or in water sources through which it can disperse to plants. This process contributes both to its ubiquity and diversity ,thus likely serving as the origin of current disease epidemics and as a reservoir of potential pathogenic strains.

Morris has made major contributions to our understanding of the population genetics of P. syringae, revising and updating the classification of the P. syringae complex and revealing many new phylogroups. By clarifying the classification of strains from a wide variety of habitats and describing their genetic and phenotypic profiles, she has revealed a fascinating diversity of biology within the P. syringae complex. Her sampling of P. syringae from a variety of natural settings has also shown that a substantial undiscovered diversity of strains of P. syringae exist and remain to be discovered. This finding provides a sobering realization that there is a very high risk that there will be further evolution and selection of strains capable of epidemic development on crop plants, but also provides guidance for better surveillance strategies to anticipate their occurrence. Her work has clarified the complex and differential contributions of type 3 secretion effectors in the virulence of P. syringae, with many environmental and even some plant-pathogenic strains lacking a canonical type 3 system. Her demonstration that the so-called “Pseudomonas viridiflava" group of strains are clearly two separate phylogroups within the P. syringae complex that can be aggressive pathogens even without a canonical type 3 secretion system. Her studies of strains infecting tomato and kiwi have revealed that many co-occurring with epidemic strains were pathogenic, not only to these crop hosts but also to a wide range of other plants, suggesting that these crop pathogens likely evolved through a small number of evolutionary events within a population of less-aggressive ancestors with a relatively wide host range. More importantly, she showed that these “environmental" strains could coexist endophytically in high numbers, thus facilitating horizontal gene exchange and the evolution of “weak" environmental strains into more aggressive pathogens. These studies have led to a new appreciation for the potential for plant pathogenic bacteria to have broad and relatively malleable host ranges, but they also reveal the weakness of current diagnostic and surveillance techniques that target specific genetic or phenotypic markers for current epidemic strains. It is through the guidance provided by her work that metagenomics surveillance of microbial communities will become common best practice for pathogen surveillance. Her recent treatise on the concept of host range of plant pathogens in the Annual Review of Phytopathology is a tour de force that is having a major impact on the way we look at the evolution of host-pathogen interactions.

Morris' work has also made plant pathology research more visible and shown it to be particularly relevant to the larger world by strongly linking plant pathogens with various global land-atmosphere feedbacks, such as those leading to precipitation. She has a rich publication record that has shown that substantial numbers of ice nucleation-active bacteria such as P. syringae occur in the atmosphere, and the modeling work done by her and her colleagues has demonstrated that they are found in sufficient concentrations to influence ice formation in clouds. She also has shown that wheat rust spores and their associated P. syringae inhabitants also are active in ice nucleation and are a likely major contributor to atmospheric processes because of the propensity of such spores to become airborne. Her work has alerted the world to inadvertent effects of climate processes associated with land use changes due to agricultural practices that will influence these microbial drivers, resulting in negative feedbacks that will likely occur with progressive climate change.