Transcriptomic analysis reveals differentially expressed genes associated with pine wood nematode resistance in resistant Pinus thunbergii

Abstract

Pine wilt disease (PWD) (caused by the nematode Bursaphelenchus xylophilus) is extremely harmful to pine forests in East Asia. As a low-resistance pine species, Pinus thunbergii is more vulnerable to pine wood nematode (PWN) than Pinus densiflora and Pinus massoniana. Field inoculation experiments were conducted on PWN-resistant and susceptible P. thunbergii, and the difference in transcription profiles 24 hours after inoculation was analyzed. We identified 2,603 differentially expressed genes (DEGs) in PWN-susceptible P. thunbergii, while 2,559 DEGs were identified in PWN-resistant P. thunbergii. Before inoculation, DEGs between PWN-resistant and PWN-susceptible P. thunbergii were enriched in the REDOX activity pathway (152 DEGs), followed by the oxidoreductase activity pathway (106 DEGs); After inoculation with PWN, however, the opposite was observed, DEGs were enriched in the oxidoreductase activity pathway (119 DEGs), followed by the REDOX activity pathway (84 DEGs). Before inoculation, according to the metabolic pathway analysis results, we found more genes upregulated in phenylpropanoid metabolic pathways and enriched in lignin synthesis pathways; cinnamoyl-CoA reductase (CCR)-coding genes related to lignin synthesis were upregulated in PWN-resistant P. thunbergii and downregulated in PWN-susceptible P. thunbergii, and the lignin content was always higher in resistant than in susceptible P. thunbergii. These results reveal distinctive strategies of resistant and susceptible P. thunbergii in dealing with PWN infections.

Resistant and Susceptible Pinus thunbergii ParL. Show Highly Divergent Patterns of Differentially Expressed Genes during the Process of Infection by Bursaphelenchus xylophilus

“…The PLR catalyzed the sequential reduction of pinoresinol to secoisolariciresinol via lariciresinol, which could lead to the structural and stereochemical diversity of lignans [ 63 ]. Lignin also affected the mechanical strength of the cell wall, which has been considered the first physical line of defense against PWN infection [ 9 , 64 ]. A more differential expression of the PLR might be associated with the regulation of lignin in response to PWN infection in resistant P. thunbergii , suggesting that the resistant phenotype had a more complicated regulation of lignin as a physical defense to suppress PWN infection.…”

“…It has been cultivated in Qingdao City, China, since 1900 and has been widely planted in coastal cities in China for almost 120 years [ 7 , 8 ]. However, the population of P. thunbergii has declined dramatically since the outbreak of pine wilt disease (PWD) [ 9 ]. PWD has severely limited the development of P. thunbergii forests.…”

Pinus thunbergii Parl. Somatic Plants’ Resistance to Bursaphelenchus xylophilus Depends on Pathogen-Induced Differential Transcriptomic Responses

“…For example, POD and CAT were more highly expressed in resistant P. thunbergii [40,68]. Similarly, the ROS-related genes were differentially expressed significantly between resistant and susceptible P. thunbergii when the branches of P. thunbergii were cut and placed in water for incubation and then inoculated with PWN [33]. In the current study, the expression levels of iron superoxide dismutase and peroxidase were higher in the resistant P. thunbergii than in the susceptible P. thunbergii at every time point.…”

Single-cell phylodynamic inference of tissue development and tumor evolution with scPhyloX

“…Using our previously published simulation framework 28 , we performed stochastic simulations of somatic mutation accumulation in a growing cell population. We used the Gillespie algorithm 29 to simulate the cell birth, differentiation and death events.…”