W188Induction of Defense Genes in Coffee Fruits from Different Coffea Species in Response to Attack by the Coffee Berry Borer, Hypothenemus hampei
Induction of Defense Genes in Coffee Fruits from Different Coffea Species in Response to Attack by the Coffee Berry Borer, Hypothenemus hampei
Date: Sunday, January 12, 2014
Time: 5:00 PM
Time: 5:00 PM
Room: Pacific Salon 4-5 (2nd Floor)
Coffee Berry Borer (CBB), Hypothenemus hampei (Ferrari) (Coleoptera: Curculionidae) is the most important insect pest of coffee worldwide. No sources of natural resistance have been identified in Coffea species. However, Coffea liberica has shown some level of antibiosis against the insect. In order to understand the interactions between C. arabica and CBB, and to characterize the response of coffee plants under CBB attack, as well as, the bases of C. liberica antibiosis, functional genomics studies were carried out using cDNA libraries, ESTs, cDNA microarrays, an oligoarray containing 43,000 coffee sequences, and RNAseq with 25 million short reads (25-300bp). The results allowed the comparison of C. liberica vs. C. arabica fruits responses to insect infestation after 24h and 48h. Out of a set of 2,500 plant sequences that exhibited differential expression under insect attack, 900 were induced in C. liberica, at least 2 times more than in C. arabica. In order to validate some of the induced genes, quantifications through real-time PCR were done. At least 12 genes showed differential expression and four genes: an isoprene synthase gene, a patatin-like protein gene, a hevein-like protein sequence, and a trypsin inhibitor known also as miraculin-like gene, CoMir, were highly upregulated in C. liberica at 24 and/or 48 h after insect infestation compared to C. arabica. For each gene, further sequence characterization and comparison were carried out between both genotypes. Functional annotation indicate that they participate in separate defense plant processes such as volatiles synthesis, lipid or chitin degradation, and proteinase inhibition, suggesting the activation of different metabolic pathways and plant defense mechanisms in coffee plants in response to insect attack. One of those processes is the methyl-erythritol 4-phosphate (MEP), or non-mevalonate pathway, that leads to the production of isoprene. The effect that isoprene has on the CBB was measured by monitoring the development of the insect from egg to adult, on coffee-artificial diets amended with increasing concentrations of isoprene. Concentrations of isoprene above 25 ppm caused mortality and developmental delay in all insect stages from larva to adult, as well as the inhibition of larvae molting. In conclusion, comparative functional genomics studies allowed the identification of at least one possible mechanism of insect induced response in coffee, providing new tools to screen and utilize Coffeagenetic resources, as well as, revealing unknown mechanisms of production of volatile substances in coffee plants with negative effects on CBB that may be applied for pest control purposes and possible interaction with other pests.
**Research Co-sponsored by the Colombian National Coffee Growers Federation and the Colombian Ministry of Agriculture