Gene expression analysis of disease-infected Pyropia tenera

Disease outbreaks devastate Pyropia aquaculture farms every year. The three most common and serious diseases are Olpidiopsis blight and red-rot disease caused by oomycete pathogens and green-spot disease caused by PyroV1 virus. We hypothesized that a basic genetic profile of molecular defenses will be revealed by comparing and analyzing genetic response of Pyropia tenera against the above three pathogens. RNAs isolated from infected thalli were hybridized onto an oligochip containing 15,115 primers designed from P. tenera ESTs. Microarray profiles of the three diseases were compared and interpreted together with histochemical observation. Massive amounts of reactive oxygen species (ROS) were accumulated in P. tenera cells exposed to oomycete pathogens. Heat shock genes and serine proteases were the most highly upregulated genes in all infection experiments. Genes involved in RNA metabolism, ribosomal proteins and antioxidant metabolism were also highly upregulated. Genetic profiles of P. tenera in response to pathogens were most similar between the two biotrophic pathogens, Olpidiopsis pyropiae and PyroV1 virus. A group of plant R-gene homologues were specifically regulated against each pathogen. Our results suggested that disease resistance of P. tenera consist of a general and constitutive defense and a genetic toolkit against specific pathogen. In this study presented here, 4 samples of Pyropia tenera were analyzed. Non disease infected P. tenera thalli was used as control and three disease infected thalli were used as treatment. RNAs isolated from non-infected and infected thalli were hybridized onto an oligochip containing 15,115 primers designed from P. tenera ESTs. Microarray profiles of each samples were compared and interpreted three times.