Page Banner

United States Department of Agriculture

Agricultural Research Service

Spiroplasmas, Phytoplasmas and Vascular Bacteria

Spiroplasma kunkelii

The evolution of phytoplasmas and plant pathogenic spiroplasmas, both wall-less bacteria, involved progressive reduction of genome sizes, approaching the minimal sets of genes required for their parasitic lifestyles; gene inactivation through pseudogene formation and the loss of gene sequences were accompanied by the gain of new capabilities enhancing host adaptation and conferring potentials for pathogenicity in insect vectors and plant hosts. Robert E. Davis


One project focuses on the development and use of new and improved technologies for detection, identification, and classification of plant pathogenic vascular-limited prokaryotes including phytoplasmas, spiroplasmas, and walled bacteria that cause potato ring rot and brown rot diseases. Ing-Ming Lee

ATP-binding cassette proteins

New knowledge derived from genome information is critical for understanding numerous biological processes that operate in plant pathogens and for developing novel strategies to combat plant diseases. Yan Zhao

Viral-Based Vectors

viral particals

This research project focuses on the development and use of viral-based vectors for the rapid delivery and expression of foreign gene sequences in plants as a means of testing sequences and protein products which may be useful in plant and animal disease control. Rosemarie W. Hammond and Lev Nemchinov


orange trees

Viroid diseases are responsible for significant losses of food and fiber. Our research goals are to obtain fundamental knowledge about the molecular interactions between viroids and their host, to apply this knowledge to the control of viroid diseases, and to develop and test viroid-induced dwarfing strategies to increase citrus production efficiency.



Defense Response Mechanisms in Sugar Beet

Root maggot infested field

Current research efforts are focused on molecular analysis of defense response mechanisms in sugar beet. Isolation and characterization of resistance genes is being pursued in order to develop effective molecular approaches for control of plant diseases with special emphasis on sugar beet pests (sugar beet root maggot, Tetanops myopaeformis) and pathogens (Cercospora beticola). Anna C. Smigocki


Apoplastic Oxidative Metabolism on Host-Pathogen in Recognition

Plant baterial recognition graphic

Our objective is to identify critical biochemical and physiological events that transpire upon contact between the plant cell and pathogen that define the outcome of the interaction. Oxidative metabolism and redox status appear to play dominant roles in this process. C. Jacyn Baker

Three citrus leaves with chlorotic yellow spots indicative of CYMV infection

Citrus Yellow Mosaic Virus Sequencing

Citrus yellow mosaic virus is a destructive disease of citrus in India. We have recently completed a thorough characterization of this virus, which included the sequencing of the entire genome and the development of a full length infectious clone of the virus. The cloned virus will be useful in defining the minimum gene set required for infection. We have also developed a diagnostic assay for this virus which can be used to protect the U.S. industry from this disease. Dr. John Hartung


Alfalfa improvement

alfalfa cow picture

Our goal is to generate fundamental knowledge on expression and regulation of genes associated with alfalfa development and stress tolerance and to use the acquired information toward improvements of alfalfa germplasm and economic viability. 

Lev Nemchinov

Last Modified: 3/1/2013
Footer Content Back to Top of Page