Comparison of the gene expression profiles of resistant and non-resistant Japanese black pine inoculated with pine wood nematode using a modified LongSAGE technique.

The Japanese black pine ( Pinus thunbergii) is highly susceptible to pine wilt disease caused by the pine wood nematode (PWN; Bursaphelenchus xylophilus). To cope with this disease, researchers and tree breeders selected PWN-resistant individuals in a previous breeding program. In an attempt to understand the mechanisms of resistance in the Japanese black pine, we created four LongSAGE (serial analysis of gene expression) libraries. A total of 20 818 tags were studied, including 5194 tags from a PWN inoculated resistant pine, 5218 a non-inoculated resistant pine, 5194 an inoculated non-resistant pine, and 5212 a non-inoculated non-resistant pine. The analysis of the libraries indicated that 14 tag species were significantly up-regulated (e.g., pathogenesis-related proteins 2 and 4, osmotin, lipoxygenase, and chalcone synthase), and nine were down-regulated (eukaryotic translation initiation factor SUI1, translationally controlled tumor protein, and xyloglucan endotransglycosylase) by the PWN inoculation in both the resistant and non-resistant pines. On the other hand, 38 tag species were significantly expressed at a higher level only in the resistant pine (catalase, dienelactone hydrolase family protein) and 25 were expressed at a higher level in the non-resistant pine (pathogenesis-related proteins 1, 2, and 3, and leucoanthocyanidin dioxygenase). These differentially expressed genes are presumed to reflect some of the differences between the resistant and non-resistant pines. Our results provide valuable information on the complex responses induced in the resistant and non-resistant pine trees in response to PWN invasion. [ABSTRACT FROM AUTHOR]