| Abstract Detail
Coffee Genomics - Morning Lecouls, Anne-Claire [1], Petitot, Anne-Sophie [1], Fernandez, Diana [1]. Genomics and coffee resistance to the orange rust fungus and to nematodes : characterisation of a WRKY transcription factor gene involved in defense responses. THE best cup quality coffee varieties (Coffea arabica L.) are highly susceptible to the root-knot nematodes (RKN) (Meloidogyne sp.) and the orange rust fungus (Hemileia vastatrix) that are important agronomic constraints in coffee-growing areas. In coffee resistant varieties, a specific resistance response known as hypersensitive reaction (HR) is early elicited by parasite infection. To identify genes specifically involved in the coffee resistance responses to rust and nematodes, a set of 2000 non-redundant ESTs were generated from subtractive (SSH) cDNA libraries enriched in genes expressed in early HR stages. Bioinformatic annotation of the ESTs revealed that around 30 % of the genes encoded putative disease resistance proteins, stress- and defense-proteins, and components of the cell signalisation pathways. Differential screening of the cDNAs libraries and real-time quantitative reverse-transcription PCR (qRT-PCR) expression analyses identified several coffee genes that showed enhanced transcript accumulation in the early stages of HR. Among differentially expressed genes, the CaWRKY1 gene displayed functional similarities with an Arabidopsis thaliana WRKY transcription factor involved in defense responses and senescence. Specific activation of CaWRKY1 occurred in response to parasites, wounding and hormonal treatments. Two divergent genomic copies (CaWRKY1a and CaWRKY1b) were identified in the allotetraploid C. arabica genome. CaWRKY1 phylogenetic analysis using related diploid Coffea species, including the putative C. arabica progenitors species C. canephora and C. eugenioides, evidenced that CaWRKY1a and CaWRKY1b are two homoeologous copies of CaWRKY1 in C. arabica. Real-time qRT-PCR quantification of CaWRKY1a and CaWRKY1b mRNA levels showed that both copies were equally expressed under several treatments, suggesting that they retained the same function in the C. arabica genome. Future work will aim at understanding the role of CaWRKY1 in the mechanism of coffee resistance to parasites.
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1 - Research Institute for Development (IRD), UMR1097 (IRD-CIRAD-INRA) Diversity and Genomes of Crop Plants, Plant Resistance Team, 911 avenue Agropolis, BP 64501, Montpellier cedex 5, 34394, France
Keywords:
coffee genomics
Meloidogyne
coffee rust
Disease resistance
WRKY.
Session: SAT01-14
Location: Hall of Ideas Room G/Monona Terrace
Date: Wednesday, July 26th, 2006
Time: 11:40 AM
Abstract ID:230 |
