HIGH-THROUGHPUT APPROACHES TO THE IDENTIFICATION OF CITRUS GENES INVOLVED IN FRUIT RESPONSE TO PENICILLIUM DIGITATUM INFECTION

We have used the Suppression Subtractive Hybridization (SSH) approach to generate a cDNA library enriched in EST from genes preferentially expressed in Penicillium digitatum-infected Citrus sinensis fruits.
A macroarray was constructed with PCR products of 1,536 clones that included clones from the SSH library and from previously characterized genes.
By performing macroarray differential hybridizations with RNA samples from control, wounded, or infected fruit peel, as well as from fruits treated with either ethylene or the ethylene perception inhibitor 1 MCP, clones with differential expression were identified and assigned to distinct gene expression patterns.
Our expression data indicate that ethylene is involved in the global response to infection.
A total of 331 clones were finally selected for sequencing.
Cluster analysis identified 211 unique ESTs whose annotation and assignment to functional categories are summarized.
Importantly, as much as 27% of the sequences identified either do not have a match in public databases or show homology with proteins of unknown function.
In selected examples, results were confirmed by Northern hybridization.
Our studies have identified novel genes and neatly exemplify the complexity of fruit reaction to fungal infection, stress response and ethylene perception.
They will be valuable tools in the future biotechnological improvement of citrus fruit response to stress conditions.

International Symposium on Biotechnology of Temperate Fruit Crops and Tropical Species

J.F. Marcos, P. Sánchez-Torres, S. Alamar, L. Zacarías, L. González-Candelas

https://doi.org/10.17660/ActaHortic.2007.738.22