A disease complex of Panicum mosaic virus (PMV) and its satellites is being investigated in my laboratory. PMV is a small positive-sense single-stranded (ss) RNA virus that infects members of the Gramineae. In the field it is commonly associated with an 824-nucleotide ssRNA satellite virus (SPMV) and satellite RNAs (satRNAs). Both SPMV and the satRNAs are encapsidated by a 17-kDa capsid protein expressed from the satellite virus genome. SPMV and satRNAs require PMV for replication. Interestingly, the accumulation of PMV as well as the induction of severe symptoms on plants is enhanced by coinfection with SPMV. This interaction of PMV and SPMV results in a serious disease, commonly known as 'St. Augustine Decline', on lawn and pasture grasses in Texas and the southern United States. Proso millet and pearl millet are experimental hosts that we use to analyze and identify the genes associated with replication, protein expression, and movement of each of the RNAs, and to investigate the interactions between PMV, SPMV, and the satRNAs. Our objectives include resolving the determinants for synergism and/or interference, gene regulation, and competitive mechanisms that pathogenic RNAs employ to maintain themselves during multiple infections.

BESC 314: Pathogens, the Environment and Society. (3 hr; writing course). The impact of microorganisms (bacteria, fungi and viruses) on the development of modern culture and society; the role pathogens played in the history of mankind and the influence of the changing environment on emerging diseases. Prerequisite: Junior or senior classification.

PLPA 620: Plant virology. (3 hr with lab). An overview of plant virology with an emphasis on the molecular biology of host-virus interactions; topics will include virus replication, gene expression, movement, symptoms, transmission, and control; current literature and techniques important to virology will be presented. Prerequisite: PLPA 601 or approval of instructor.