Identification of novel genes differentially expressed in compatible and incompatible interactions between rice and Pseudomonas avenae

Establishment of a plant-pathogen interaction involves differential gene expression in both organisms. To isolate rice genes induced during either compatible or incompatible interactions, we performed a comparative analysis of expression patterns in cultured rice cells, inoculated with either compatible or incompatible strains of Pseudomonas avenae, by fluorescence differential display (FDD). Using 52 sets of arbitrary primer combinations, two cDNAs (IAI1 and IAI2) expressed in incompatible strain-inoculated rice cells and one cDNA (CAII) expressed in compatible strain inoculated cells, were identified. A hydropathy profile revealed that the IAI1 protein spans the membrane at a putative transmembrane domain. The deduced amino acid sequence of IAI2 shares considerable homology with Bowman-Birk proteinase inhibitors over the majority of the sequence. The deduced CAII protein is rich in glycine, containing a putative signal peptide with a potential cleavage site, suggesting its membership in the glycine-rich protein (GRP) family. GRPs are thought to be structural cell wall proteins. When a GFP fusion with the CAII gene was introduced into onion cells by bombardment, green fluorescence of the cell wall was observed. These data suggest that CAII is involved in the repair of cell wall injuries by the compatible strain of P. avenae. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.