Ornamental Plants Annual Reports and Research Reviews 2000

Special Circular 177-01

Partnership with the Green Industry: The New Molecular and Cellular Imaging Center

Charles R. Krause

The United States Department of Agriculture (USDA), in cooperation with The Ohio State University/Ohio Agricultural Research and Development Center (OARDC), has unique opportunities for floricultural and nursery crop research at OARDC and for enhancing cooperative federal and state programs.

A cold field emission scanning electron microscope (CFESEM), a variable pressure scanning electron microscope (VPSEM), and a transmission electron microscope were recently purchased with joint federal and state funds.

The United States Department of Agriculture, Agricultural Research Service (ARS), Application Technology Research Unit (ATRU), and the Ohio State University's Ohio Agricultural Research and Development Center combined resources to upgrade the College of Food, Agricultural, and Environmental Sciences' electron microscope facility located on Ohio State University's campus at Wooster. The new name of this facility is the Molecular and Cellular Imaging Center (MCIC), which now includes additional equipment capable of performing molecular biological analyses.

A substantial savings of more than $250,000 was made possible with this joint acquisition through multi-instrument and federal purchase discounts in 1999. Such joint purchases permit the efficient use of federal and land-grant agricultural funds, stimulating increased cooperative research projects with graduate students, post-doctoral cooperators, and visiting scientists. At the same time, such joint purchases avoid the duplication of facilities.

This new imaging technology allows improved digital electron microscopy technology using CFESEM and VPSEM and provides higher magnification and clearer views of agricultural phenomena to solve some of the problems of American agriculture.

Higher resolution and visualization of newly developed biological pesticides, disease development, and pathogens and pests is now possible - at a level five to 10 times better than was previously possible. The Center also provides the opportunity for the performance of good science to answer difficult, long-term environmental questions involving food safety, water quality, and worker protection.

One of the long-term goals of both institutions is the reduction of pesticide usage through more efficient spraying and distribution. This goal will be enhanced by the following:

• Improved fungicide canopy penetration and coverage in nurseries and greenhouses.
• Compatibility between conventional chemical fungicides and biological control strategies, discovering alternative fungicides.
• Studies of different formulations, such as smokes, aerosols, cold-foggers, and other low-volume application technologies.

This new equipment permits clearer imaging of much smaller features with higher magnification of target surfaces than was previously attainable. Increased performance in numbers of observations and analyses with minimal specimen preparation time greatly improves analytical turn-around time.

Specific studies are:

• Pesticide cuticle penetration.
• Cuticle morphology and observations of host-parasite interactions.
• Measurement of residue on host tissues (in situ).
• Spatial relationships and the ultrastructure of pathogens and pests on hydrated samples.
• Direct assessment of application methods, host-parasite relationships, plant stress, nozzle wear, spray drift, and canopy penetration.
• Visualization and detection of bacterial and viral plant pathogens, to identify sites of physiological activity (10 Å required).
• Bio-pesticide characterization to enhance consumer confidence in agricultural product safety.

A photomicrograph of the fungus that causes apple scab disease on crabapple (x1500) taken with the new cold field emission scanning electron microscope located at the OARDC.

Comparison of Electron Microscopes
Instruments	Resolution/ Accelerating Voltage/ Magnification Attainable	Specimen Prep/ Coating	X-Ray Microanalysis Available	Types of Samples Observable w/o Artifacts
S-500 SEM (previous unit)	Å / 20kV; SE: x60,000	Au, Pd, C, etc.	Yes	Plants, insects, animals.
S-3500 Variable Pressure SEM	50 Å / 25kV, BSE: x20,000; SE: > x100,000	Not required	Not presently available	Hydrated plants, insects, in situ observation of exogenous substances.
S-4700 Cold Field Emission SEM	12Å @ 15kV SE: > x300,000 BSE: > x50,000	Varies, usually not	Yes	Plant surfaces w/ pathogens, fungicides, insects, or animals.

References

Krause, C. R. and R. C. Derksen, R. D. Brazee and R. D. Fox. 2000. Cold field emission scanning electron microscopy permits unique views of plant pathogens. Phytopathology 90: S43 (Abstract).

Krause, C. R. and R. C. Derksen. 2000. Comparison of electrostatic and coldfog sprayers with cold field emission scanning electron microscopy and energy dispersive X-ray microanalysis. Proc. British Crop Protection Council. Brighton, UK. (In press).

Acknowledgements

A portion of this research was supported by grants from the Horticultural Research Institute.