Whole WRKY gene family transcription analysis in rice during biotic and abiotic stress.

The WRKY gene family has a very ancient origin but has faced extensive duplication only in the plant kingdom so much that Arabidopsis (Arabidopsis thaliana) has 74 copies of WRKY genes encoding transcription factors while 109 can be found in Rice (Oryza sativa L.). Several studies in the last decade has pointed their involvement in an heterogeneous number of biological processes, from development to hormone signalling, dormancy and senescence, but a wide number of WRKY genes are transcriptionally regulated during biotic or abiotic stresses. To investigate involvement of WRKY genes upon host and non-host infection (different strain of Magnaporthe grisea) and osmotic stress in Rice, we performed a gene family transcription analysis using custom microarray. Results indicate that a relevant part of WRKY genes are involved during at least one of these stresses, that there is little difference in transcriptional regulation between host and non-host infection or between different tissues upon the same osmotic stress. Moreover, are evident groups of genes that, often with opposite behaviour, are co-regulated in all or most of the studied conditions. We thus formulated the hypothesis that WRKY genes might be part of co-regulatory networks with other WRKY genes. Keywords: stress response We analyzed 40 arrays and tested 6 conditions: BR29 (Non-host Pathogen), BR32 (Non-host Pathogen), FR13 (Host pathogen), Osmotic leaves 5 hours, Osmotic roots 1 hour and Osmotic roots 5 hours. 2 biological replicated were analyzed and between 2 to 4 technical replicates applied for each biological sample.