De novo assembly and transcriptome analysis of the Pinus densiflora response to pine wilt disease in nature

Pine trees have economically and ecologically important roles. However, since the beginning of the twentieth century, a large number of trees have been seriously damaged by pine wilt disease (PWD). Although many studies have been conducted into blocking the spread of PWD, relatively few studies have been performed to examine the transcriptional responses of pine trees to the pine wood nematode (PWN). Here, we performed de novo assembly and analysis of the Pinus densiflora transcriptome by next-generation sequencing (NGS), to identify transcriptional responses that are related to the PWD infection. We identified that 586 of 71,003 assembled unigenes were differentially expressed after PWD infection. Gene ontology analysis showed that biological process terms related to defense responses (response to oxygen containing compound, response to jasmonic acid, response to biotic stimulus, cinnamic acid biosynthetic process, etc.) were significantly enriched in the DEGs after PWD infection. Our results suggested that jasmonic acid signaling is important in controlling defense response against PWD infection and is finely tuned by coordinated expression of positive and negative regulators. These findings contribute to our understanding of the transcriptional responses of P. densiflora to PWN, and could facilitate the development of biomarkers for diagnosis of PWD.