Array-based gene expression allows rapid screening of a large number of plant genes for differential expression in response to environmental stimuli. We have used an array of 384 randomly selected sweet orange (Citrus sinensis L. Osbeck) cDNAs for differential gene expression analysis in leaf tissue. Comparisons were performed with young expanding leaves undamaged, and damaged by either Diaprepes root weevil adult feeding or mechanical simulation of feeding, and mature source leaves undamaged and damaged by mechanical feeding simulation. In young leaves, the majority of the damage-induced changes in gene expression were similar for both damage types. Increases in transcript abundance were observed for a group of metallothionein-related sequences, carbonate dehydratase, an unknown protein, and a pectin methyl esterase. Interestingly, damage induced increases mimicked developmental changes as leaves matured form sink to source leaves. More genes showed significant reductions in associated transcript levels in response to the damages, and there was a greater variability in this decline among the treatments. Damage-induced declines did not mimic development changes as was observed for up-regulated genes. Very few changes in mature leaves in response to the mechanical damage were observed. Although the array contained seven sequences encoding putative pr-proteins, and at least one related to known pathogen induced sequence, the transcript level of these did not respond to any of the damage treatments. Differential expression results will be presented with respect to the effected metabolic pathways, and show the presence of previously unknown relationships between gene expression and stress response.
Species 1: Coleoptera Curculionidae Diaprepes abbreviatus (Diaprepes root weevil)
Species 2: Sapindales Rutaceae Citrus sinensis (sweet orange)
Keywords: plant gene expression
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