I have expertise in plant pathology, particularly diseases of plants caused by bacteria, especially fire blight of apple, pear and related plants and bacterial diseases of onions. I have functioned broadly in these respects, in teaching, research and extension. My research activity has covered epidemiology and control, molecular genetics, genomics and proteomics. Much of my recent activity has been fundamental in nature, however, application of fundamental knowledge to applied problems is a strong motivation. I advise others informaly concerning bacterial diseases and the identification and manipulation of the pathogens.
My responsibility for work on diseases of tree fruit evolved to emphasize molecular genetic studies of phytopathogenic bacteria, particularly the fire blight pathogen, Erwinia amylovora. Concurrently, the Department’s needs for instruction in phytobacteriology led me to offer courses in bacterial plant pathogens for some 15 years. The more recent call for undergraduate courses led me to volunteer to teach a “Senior Seminar” for students majoring in Biology and Society.
Research studies over the last twenty-five years resulted in the identification and characterization of many hrp genes that encode products critical to disease development as well as several plant proteins with which the bacterial proteins interact. One of those genes, hrpN encodes a protein (harpin) that has been commercialized as a resistance inducer and plant growth enhancer. Recent research involved characterizing the genome of E. amylovora and determining the possible role of several genes and gene products in interactions with host and non-host plants. Utilization of bacterial genes and their interacting proteins of plants has been explored as an approach to control of plant disease. In addition, the genetic basis of host-specificity of strains of the fire blight pathogen for plants of two subfamilies of the Rosaceae family of plants was explored.
In 2007, my program began to address bacterial disease problems of onions. This partial redirection of effort was in response to increasing problems experienced by New York onion growers. A pathogen new to New York onions, Pantoea ananatis, was identified and characterized. A year later, Enterobacter cloacae was newly identified in New York as the cause of serious losses for several large growers of onions. Several other bacteria of concern to New York onion growers are currently being studied. Present emphasis is placed on rapidly identifying and characterizing the bacteria that are responsible for losses, determining their epidemiology, genetics of pathogenicity and developing strategies for effective measures to reduce disease incidence and losses.
Outreach and Extension Focus
An innovative outreach project aimed primarily at secondary school biology students in New York State is underway. It`s a collaboration with Cornell`s Institute for Biology Teaching (CIBT), which is supported by the Howard Hughes Medical Institute and the New York State Center for Advanced Technology. A DVD and a study guide were produced aimed at introducing secondary school students and their teachers to several important concepts: that bacteria can cause disease in plants; techniques for safe handling of bacterial plant pathogens; that specific genes are needed for disease-causing ability; bioinformatics strategies useful for annotation of a genome sequence, and the use of reverse genetics laboratory tests to assess gene function. The program was presented to a group of secondary school science teachers, who will test the materials and possibly suggest changes to the project for use in classrooms. The materials also will be made available on the internet. The secondary school outreach project is being revised and expanded for presentation to the agricultural community, especially Cooperative Extension Educators in the field and fruit growers. One of the major objectives is to foster better understanding by the target audiences of fundamental molecular biological research as applied to fruit crops and their pests and pathogens. Greater understanding of the relevance of molecular biological research, and its possible future benefit, likely will result in enhanced appreciation by the agricultural community and the general public.
Since becoming involved in research on bacterial problems in onions, I have also functioned as an extension resource for the topic. For example, I address onion growers and others in meetings to provide research updates and address questions relative to onion diseases. I also visit farms and examine problems, make diagnoses, and advise growers and CCE staff on bacterial problems.
The recent call for more undergraduate courses, and particularly Biology and Society "Senior Seminars" led me to volunteer to teach a “Senior Seminar” for students majoring in Biology and Society. That course, "Microbes and Food: Contemporary Issues Affecting Humanity", BIOS 4161 and PLPA 4161, utilizes my interest in microbes and their important role in society. The course emphasizes guided student presentations, discussions and debates. Several field trips to view microbes in action are taken during the semester. The Department’s needs for instruction in phytobacteriology led me to offer courses in bacterial plant pathogens for some 15 years, which ended in 2004.
Ithaca Coodindinator of PLPA 6820, Graduate Student Research Updates
- Mansfield, J., Genin, S., Magori, S., Citovsky, V., Sriariyanum, M., Ronald, P., Dow, M., Verdier, V., Beer, S. V., Machado, M. A., Toth, I., Salmond, G., & Foster, G. D. (2012). Top 10 Plant Bacteria in Molecular Plant Pathology. Molecular Plant Pathology. 13:614-629.
Presentations and Activities
- BACTERIAL DISEASES OF ONION IN NEW YORK. 2012 National Allium Research Conference . December 2012. National Allium Association. Las Cruces, NM.
- RESEARCH YIELDS GREATER UNDERSTANDING OF BACTERIAL DISEASES OF ONION IN NEW YORK. Orange County Onion School. March 2012. Cornell Cooperative Extension. Middletown NY.
- RESEARCH YIELDS GREATER UNDERSTANDING OF BACTERIAL DISEASES OF ONION IN NEW YORK. 2012 Empire State Fruit & Vegetable Expo.. January 2012. Cornell Cooperative Extension. Syracuse NY.
- Onion Bacterial Problems The Most Serious Uncontrollable Problem. Oswego County Vegetable Growers Association. December 2011. Cornell Cooperative Extension. Oswego NY.
- Onion Bacterial Problems The Most Serious Uncontrollable Problem. Annual Elba Muck Onion Twilight Meeting. August 2011. Cornell Cooperative Extension. Elba NY.
- Studies of bacterial problems of onion in New York -- 2010. 2011 Empire State Fruit & Vegetable Expo.. January 2011. Empire State Fruit & Vegetable Association. Syracuse N.