Poster: Plant Pathogen/Symbiont Interactions

Abs # 689: Induction of gene expression in cacao (Theobroma cacao) by elicitors of the pathogen response.

Presenter:	Verica, Joseph A., joeverica@yahoo.com
Authors	Verica, Joseph A. (A)   Maximova, Siela  N. (A)   Strem, Mary  (B)   Druckenmiller, Marlin  (C)   Carlson, John E. (C)   Bailey, Bryan  (B)   Guiltinan, Mark J. (A)
Affiliations:	(A): Department of Horticulture, Pennsylvania State University, 302 Wartik Lab, University Park, PA 16802. (B): United States Department of Agriculture, Agricultural Research Station, Biocontrol of Plant Diseases Laboratory, Beltsville, MD 20705 (C): Department of Forest Resources, Pennsylvania State University, University Park, PA 16802.

Pathogenic diseases are a major constraint to cocoa (Theobroma cacao) production, causing annual crop losses of 30-40%. Although disease resistance pathways have been intensely studied in a number of plant species, studies in cocoa are limited. In many plants, activation of defense responses is controlled, in part, by signal transduction pathways mediated by endogenous signaling molecules such as salicylic acid (SA), jasmonic acid (JA) and ethylene. In an effort to gain a better understanding of how cocoa plants respond to pathogens, we have employed suppressive subtractive hybridization (SSH) cDNA libraries, macroarray hybridization technology, high throughput DNA sequencing and bioinformatics in an effort to identify cacao genes induced by these signaling molecules. In addition, we also investigated gene activation by nep1, a defense elicitor protein produced by some plant pathogens. We have screened over 4000 SSH cDNA clones and identified a set of genes induced by these elicitors. Their potential roles in the defense response and the regulatory interactions between these pathways in cacao will be discussed.