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Plant-pathogen interactions

DOI: 10.1186/gb-2000-1-2-reports0062

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Using cDNA amplified fragment length polymorphism (AFLP), Durrant et al. have for the first time comprehensively examined early gene expression changes, which are independent of the oxidative burst, induced during a race-specific plant pathogen interaction. By choosing a time window that covers the first 30 minutes after pathogen recognition, they focused exclusively on early response genes, some of which may encode regulators of successive defense responses, including the oxidative burst.The tomato R gene Cf9 confers resistance to races of the fungal pathogen Cladosporium fulvum expressing the Avr9 avirulence gene. A cDNA-AFLP-based RNA fingerprinting analysis was applied to cultured tobacco cells that contain Cf9 as a transgene, 30 minutes after treatment with recombinant Avr9 protein. Based on non-selective amplification of cDNA fragments representing cellular mRNAs, this method allows gene expression profiling which requires, in contrast to cDNA microarrays, no prior assumptions about the set of genes that might be affected.Using 512 primer combinations, approximately 30,000 AFLP fragments were visualized. The authors estimate that this may represent more than 75% of all tobacco transcript species. Differential expression in response to Avr9 could be observed for 290 of these fragments (in 273 cases expression was upregulated). The genes represented by these fragments were named ACRE (Avr9/Cf9 rapidly elicited) genes. Application of a specific inhibitor of the oxidative burst, diphenyleneiodonium, showed that only 4% of the early expression changes are dependent on AOS. Furthermore, Avr9-induced expression seems, at least in some cases, to be independent of de novo protein biosynthesis, as determined by experiments with the translation inhibitor cycloheximide. Only 42 ACREs show similarity to known genes. A subset of these encodes potential regulatory proteins, such as protein kinases, protein phosphatases and transcription factors including EREBPs (ethylene res


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