Pine wilt disease caused by pine wood nematode (Bursaphelenchus xylophilus, PWN) is a severe forest disease of the genus Pinus. Masson pine as an important timber and oleoresin resource in South China, is the major species infected by pine wilt disease. However, the underlying mechanism of pine resistance is still unclear. Here, we performed a transcriptomics analysis to identify differentially expressed genes associated with resistance to PWN infection. By comparing the expression profiles of resistant and susceptible trees inoculated with PWN at 1, 15, or 30 days post-inoculation (dpi), 260, 371 and 152 differentially expressed genes (DEGs) in resistant trees and 756, 2179 and 398 DEGs in susceptible trees were obtained. Gene Ontology enrichment analysis of DEGs revealed that the most significant biological processes were “syncytium formation” in the resistant phenotype and “response to stress” and “terpenoid biosynthesis” in the susceptible phenotype at 1 and 15 dpi, respectively. Furthermore, some key DEGs with potential regulatory roles to PWN infection, including expansins, pinene synthases and reactive oxidation species (ROS)-related genes were evaluated in detail. Finally, we propose that the biosynthesis of oleoresin and capability of ROS scavenging are pivotal to the high resistance of PWN.

Pinus massoniaia Lamb has gained more and more attention as the most important tree species for timber and forestation in South China. Gene expression studies are of great importance to identify new and elite cultivars. Real-time quantitative PCR, a highly sensitive and specific method, is commonly used in the analysis of gene expression. The appropriate reference genes must be employed to normalize the calculation program for ascertaining repeatable and significant results. Herein, eleven housekeeping genes were evaluated during different stages of P. massoniana post nematode inoculation in this study. Three statistical approaches such as geNorm, NormFinder and BestKeeper were selected to analyze the stability of candidate genes. The results indicated that U2af and β-TUB were the most stable reference genes. These two genes could be used for the normalization in most of the experiments of P. massoniana, while Histone and AK were the least stable ones. In addition, EF expressed at the lowest average Ct value was the most abundant candidate gene. As an important gene associated with defense mechanisms, ABC transporter was analyzed by qRT-PCR, and the results were used to confirm the reliability of two genes. The selected reference genes in the present study will be conducive to future gene expression normalized by qRT-PCR in P. massoniana.

No abstract

No abstract

No abstract