Chitosan oligosaccharide induces plant resistance gene expression in Pinus massoniana

Abstract

Chitosan oligosaccharides are the main degradation products from chitosan or chitin and have been reported to induce resistance to diseases in herbaceous plants like cucumber and Arabidopsis. Concomitantly, pine wilt disease is a devastating disease of conifer tree species. Here, we hypothesized that chitosan oligosaccharides induce plant resistance gene (PRG) expression in the woody plant Masson pine, Pinus massoniana. Chitosan oligosaccharides were inoculated into P. massoniana seedlings and the BGISEQ-500 platform was used to generate transcriptomes from chitosan oligosaccharide-treated P. massoniana and control seedlings. A total of 501 differentially expressed genes (DEGs) were identified by comparing the treatment and control groups. A total of 251 (50.1%) DEGs were up-regulated in the treatment relative to the control seedlings and 250 (49.9%) were down-regulated. Inoculation of chitosan oligosaccharide induced the expression of 31 PRGs in P. massoniana seedlings and the relative expression levels of six of the PRGs were verified by RT-qPCR. This is the first study to demonstrate that chitosan oligosaccharide induces the expression of PRGs in a tree species. These results provide important insights into the function of chitosan oligosaccharides and further the prospects of developing a chitosan oligosaccharide-based immune inducer for controlling pine wilt disease.