Submitted to: Plant Cell Reports
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/10/2004
Publication Date: 8/20/2004
Citation: Verica, J.A., Maximova, S., Strem, M.D., Carlson, J., Bailey, B.A., Guiltinan, M. 2004. Isolation of early defense-related ests from subtracted-normalized cdna libraries of elicited cacao (theobroma cacao l.) leaves. Plant Cell Reports 23:404-413. Interpretive Summary: Theobroma cacao (cacao), the source of chocolate, is a tropical tree grown largely by small farmers in tropical climates. There are several diseases that threaten cacao production. Cacao production in South and Central America has been severely affected. Understanding the genetic control of cacao resistance to disease is critical to developing control measures for these diseases. We have characterized the responses of cacao to treatments known to induce resistance to disease in other plant species. In addition, a phytotoxic protein was used. Of the 1,256 genes identified in this study, 330 represented genes induced by one or more of the treatments studied. This work establishes a database of cacao genes for future detailed study. The knowledge gained concerning the expression of these genes can be exploited in the development of cacao varieties with resistance to plant pathogens. Resistant varieties will allow sustainable production of cacao assuring stable yields for farmers dependent upon the crop for their lively hood and assuring the supply required for dependent industries and associated consumers.
Technical Abstract: Pathogenic diseases represent a major constraint to the growth and yield of cacao (Theobroma cacao L.). Ongoing research on model plant systems has revealed that defense responses are activated via signaling pathways mediated by endogenous signaling molecules such as salicylic acid, jasmonic acid and ethylene. Activation of plant defenses is associated with changes in the expression of large numbers of genes. To gain a better understanding of defense responses in cacao, we have employed suppressive subtractive hybridization (SSH) cDNA libraries, macroarray hybridization analysis, high throughput DNA sequencing and bioinformatics to identify cacao genes induced by these signaling molecules. Additionally, we investigated gene activation by a phytotoxic elicitor-like protein, Nep1. We have identified a unigene set of 1,256 members, including 330 members representing genes induced during the defense response.