Primary Metabolite Adjustments Associated With Pinewood Nematode Resistance in Pinus pinaster

The pinewood nematode (PWN) Bursaphelenchus xylophilus is the causal agent of the pine wilt disease (PWD) and represents one of the major threats to conifer forests. The detection of the PWN in Portugal, associated with Pinus pinaster, increased the concern of its spread to European forests. Despite its susceptibility to PWD, genetic variability found among P. pinaster populations has been associated with heritable PWD resistance. Understanding the mechanisms underlying tree resistance constitutes a valuable resource for breeding programs toward more resilient forest plantations. This study investigated changes in anatomy, chlorophyll a fluorescence (ChlF), and primary metabolism in susceptible and resistant P. pinaster half-sib plants, after PWN inoculation. Susceptible plants showed a general shutdown of central metabolism, osmolyte accumulation, photosynthetic inhibition, and a decrease in the plant water status. The ChlF transient rise (OJIP curve) revealed the appearance of L- and K-bands, indicators of environmental stress. In contrast, resistant plants revealed a regulated defense response and were able to restrict PWN migration and cellular damage. Furthermore, the accumulation of γ-aminobutyric acid (GABA) and succinate suggested a role of these metabolites in PWD resistance and the possible activation of the GABA shunt. Altogether, these results provide new insights to the role of primary metabolism in PWD resistance and in the selection of resistant phenotypes for disease mitigation.

Download Full-text

Chitosan increases Pinus pinaster tolerance to the pinewood nematode (Bursaphelenchus xylophilus) by promoting plant antioxidative metabolism

Scientific Reports ◽

10.1038/s41598-021-83445-0 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Marta Nunes da Silva ◽

Carla S. Santos ◽

Ana Cruz ◽

Adrián López-Villamor ◽

Marta W. Vasconcelos

Keyword(s):

Phenolic Compounds ◽

Pinus Pinaster ◽

Plant Defence ◽

Pine Wilt Disease ◽

Bursaphelenchus Xylophilus ◽

Nematode Population ◽

Post Inoculation ◽

Pinewood Nematode ◽

Plant Tolerance ◽

The Moment

AbstractThe pine wilt disease (PWD), for which no effective treatment is available at the moment, is a constant threat to Pinus spp. plantations worldwide, being responsible for significant economic and environmental losses every year. It has been demonstrated that elicitation with chitosan increases plant tolerance to the pinewood nematode (PWN) Bursaphelenchus xylophilus, the causal agent of the PWD, but the biochemical and genetic aspects underlying this response have not been explored. To understand the influence of chitosan in Pinus pinaster tolerance against PWN, a low-molecular-weight (327 kDa) chitosan was applied to mock- and PWN-inoculated plants. Nematode population, malondialdehyde (MDA), catalase, carotenoids, anthocyanins, phenolic compounds, lignin and gene expression related to oxidative stress (thioredoxin 1, TRX) and plant defence (defensin, DEF, and a-farnesene synthase, AFS), were analysed at 1, 7, 14, 21 and 28 days post-inoculation (dpi). At 28 dpi, PWN-infected plants elicited with chitosan showed a sixfold lower nematode population when compared to non-elicited plants. Higher levels of MDA, catalase, carotenoids, anthocyanins, phenolic compounds, and lignin were detected in chitosan-elicited plants following infection. The expression levels of DEF gene were higher in elicited plants, while TRX and AFS expression was lower, possibly due to the disease containment-effect of chitosan. Combined, we conclude that chitosan induces pine defences against PWD via modulation of metabolic and transcriptomic mechanisms related with plant antioxidant system.

Download Full-text

Insights Into the Mechanisms Implicated in Pinus pinaster Resistance to Pinewood Nematode

Frontiers in Plant Science ◽

10.3389/fpls.2021.690857 ◽

2021 ◽

Vol 12 ◽

Author(s):

Inês Modesto ◽

Lieven Sterck ◽

Vicent Arbona ◽

Aurelio Gómez-Cadenas ◽

Isabel Carrasquinho ◽

...

Keyword(s):

Cell Wall ◽

Pinus Pinaster ◽

Pine Wilt Disease ◽

Bursaphelenchus Xylophilus ◽

Pinewood Nematode ◽

Acetyl Bromide ◽

Resistance Response ◽

Transcriptional Changes ◽

Disease Impact ◽

Cell Wall Reinforcement

Pine wilt disease (PWD), caused by the plant–parasitic nematode Bursaphelenchus xylophilus, has become a severe environmental problem in the Iberian Peninsula with devastating effects in Pinus pinaster forests. Despite the high levels of this species' susceptibility, previous studies reported heritable resistance in P. pinaster trees. Understanding the basis of this resistance can be of extreme relevance for future programs aiming at reducing the disease impact on P. pinaster forests. In this study, we highlighted the mechanisms possibly involved in P. pinaster resistance to PWD, by comparing the transcriptional changes between resistant and susceptible plants after infection. Our analysis revealed a higher number of differentially expressed genes (DEGs) in resistant plants (1,916) when compared with susceptible plants (1,226). Resistance to PWN is mediated by the induction of the jasmonic acid (JA) defense pathway, secondary metabolism pathways, lignin synthesis, oxidative stress response genes, and resistance genes. Quantification of the acetyl bromide-soluble lignin confirmed a significant increase of cell wall lignification of stem tissues around the inoculation zone in resistant plants. In addition to less lignified cell walls, susceptibility to the pine wood nematode seems associated with the activation of the salicylic acid (SA) defense pathway at 72 hpi, as revealed by the higher SA levels in the tissues of susceptible plants. Cell wall reinforcement and hormone signaling mechanisms seem therefore essential for a resistance response.

Download Full-text

Pinus pinaster Early Hormonal Defence Responses to Pinewood Nematode (Bursaphelenchus xylophilus) Infection

Metabolites ◽

10.3390/metabo11040227 ◽

2021 ◽

Vol 11 (4) ◽

pp. 227

Author(s):

Ana M. Rodrigues ◽

Swen Langer ◽

Isabel Carrasquinho ◽

Ed Bergström ◽

Tony Larson ◽

...

Keyword(s):

Pinus Pinaster ◽

Current Knowledge ◽

Acid Methyl Ester ◽

Pine Wilt Disease ◽

Bursaphelenchus Xylophilus ◽

Pinewood Nematode ◽

Crop Species ◽

Jasmonic Acid Methyl Ester ◽

Defence Responses ◽

Pinus Spp

The pinewood nematode (PWN) is the causal agent of pine wilt disease, a pathology that affects conifer forests, mainly Pinus spp. PWN infection can induce the expression of phytohormone-related genes; however, changes at the early phytohormone level have not yet been explored. Phytohormones are low-abundance metabolites, and thus, difficult to quantify. Moreover, most methodologies focus mainly on Arabidopsis or crop species. This work aimed to validate a fast (run time 6.6 min) liquid chromatography-triple quadrupole tandem mass spectrometry (LC-QqQ-MS/MS) analytical method to quantify 14 phytohormones in Pinus pinaster stem tissues. This method was further applied to evaluate, for the first time, early phytohormone changes in susceptible and resistant phenotypes of P. pinaster 24, 48 and 72 h after inoculation (HAI) with PWN. A significant increase in salicylic acid (SA, 48 and 72 HAI) and jasmonic acid methyl ester (JA-ME, 72 HAI) was observed in susceptible phenotypes. Results indicate that the higher susceptibility of P. pinaster to PWN infection might result from an inefficient trigger of hypersensitive responses, with the involvement of JA and SA pathways. This work provides an important update in forest research, and adds to the current knowledge of Pinus spp. defence responses to PWN infection.

Download Full-text

In Silico Screening of Agonist and Antagonist Natural Compounds from Reported Essential Oils against Bursaphelenchus xylophilus

Chemistry Proceedings ◽

10.3390/ecsoc-24-08386 ◽

2020 ◽

Vol 3 (1) ◽

pp. 31

Author(s):

Jorge M. S. Faria ◽

Ana Margarida Rodrigues ◽

Pedro Barbosa ◽

Manuel Mota

Keyword(s):

Essential Oils ◽

Pine Wilt Disease ◽

Natural Compounds ◽

Bursaphelenchus Xylophilus ◽

Pinewood Nematode ◽

Highly Active ◽

Bibliographic Data ◽

Agonist And Antagonist ◽

Containment Strategy ◽

Detailed Chemical

Chemical control has been the most effective and reliable containment strategy in integrated pest management of pine wilt disease (PWD), caused by the pinewood nematode (PWN), Bursaphelenchus xylophilus. Yet, large spectrum nematicides can be dangerous to human health and the environment. Essential oils (EOs) are safer sustainable alternatives, being composed of highly active natural compounds. A survey of bibliographic data on the detailed chemical composition and activity of the EOs used against the PWN allowed pinpointing monoterpenes as the main source of structures with agonist or antagonist properties. Transversal EO data treatment can identify potential highly active anti-PWN compounds.

Download Full-text

Study of symptoms and gene expression in four Pinus species after pinewood nematode infection

Plant Genetic Resources ◽

10.1017/s1479262111000062 ◽

2011 ◽

Vol 9 (2) ◽

pp. 272-275 ◽

Cited By ~ 5

Author(s):

Albina R. Franco ◽

Carla Santos ◽

Mariana Roriz ◽

Rui Rodrigues ◽

Marta R. M. Lima ◽

...

Keyword(s):

Virulent Strain ◽

Pine Wilt Disease ◽

Bursaphelenchus Xylophilus ◽

Wilt Disease ◽

Pinewood Nematode ◽

Pine Trees ◽

Severe Infections ◽

Genomic Results ◽

Avirulent Isolate

Pine wilt disease, caused by the pinewood nematode Bursaphelenchus xylophilus (Steiner and Buhrer) Nickle, is originating severe infections in pine trees. The disease is detected when external symptoms appear (e.g. needle chlorosis), but trees could remain asymptomatic for long periods and serve as a long-term host. The primary goal of this study was to assess the effect of inoculation with an avirulent isolate of B. xylophilus (C14-5) on different Pinus spp. seedlings (P. sylvestris, P. nigra, P. pinea and P. pinaster). At the same time, seedlings were also inoculated with a virulent strain, HF, in order to compare the phenotypic and genomic results of the two types of inoculations. The effect of inoculation was determined in terms of expression of various Pinus genes potentially involved in the response to the disease.The results suggest that P. pinea and P. nigra are more resistant to infection by the nematode than P. sylvestris and P. pinaster. The phenotypic and genetic differences were more marked among P. pinea and P. pinaster.

Download Full-text

α-l-Fucosidases from Bursaphelenchus xylophilus Secretome—Molecular Characterization and Their Possible Role in Breaking Down Plant Cell Walls

Forests ◽

10.3390/f11030265 ◽

2020 ◽

Vol 11 (3) ◽

pp. 265

Author(s):

Joana M.S. Cardoso ◽

Luís Fonseca ◽

Isabel Abrantes

Keyword(s):

Cell Wall ◽

Molecular Characterization ◽

Three Dimensional ◽

Pine Wilt Disease ◽

Bursaphelenchus Xylophilus ◽

Pinewood Nematode ◽

Cell Wall Degrading Enzymes ◽

Degrading Enzymes ◽

Host Trees ◽

Resin Canals

The pinewood nematode (PWN) Bursaphelenchus xylophilus, the causal agent of the pine wilt disease (PWD), enters above-ground parts of the tree, migrates through the resin canals and feeds on plant cells causing extensive damage. In order to penetrate the cell wall and establish a parasitic relationship with host trees, the PWN needs to secretea mixture of active cell wall degrading enzymes. In maritime pine, Pinus pinaster, which is high susceptible to PWN, xyloglucan is the major hemicellulosic polysaccharide in primary cells. The xyloglucan backbone is susceptible to hydrolysis by numerous endoglucanases, some of them specific to xyloglucan. However, to completely degrade xyloglucan, all substitutions on the glucan backbones must be released, and l-fucose residues in xyloglucan branches are released by α-l-fucosidases. In the present study, the molecular characterization of two α-l-fucosidases found in PWN secretome was performed. Moreover, a novel α-l-fucosidase was identified and its cDNA and gene sequence were determined. The three-dimensional structures of these α-l-fucosidases were predicted and the transcript levels were analyzed, thus providing new insights into fundamental PWN biology and the possible role of these proteins as cell wall degrading enzymes.

Download Full-text

Pine Wilt Disease And The Pinewood Nematode, Bursaphelenchus Xylophilus

Integrated Management of Fruit Crops Nematodes ◽

10.1007/978-1-4020-9858-1_11 ◽

2009 ◽

pp. 253-274 ◽

Cited By ~ 10

Author(s):

Manuel M. Mota ◽

Kazuyoshi Futai ◽

Paulo Vieira

Keyword(s):

Pine Wilt Disease ◽

Bursaphelenchus Xylophilus ◽

Wilt Disease ◽

Pinewood Nematode ◽

Pine Wilt

Download Full-text

Pine chemical volatiles promote dauer recovery of a pine parasitic nematode, Bursaphelenchus xylophilus

Parasitology ◽

10.1017/s0031182019001264 ◽

2019 ◽

Vol 147 (1) ◽

pp. 50-57 ◽

Cited By ~ 2

Author(s):

Wei Zhang ◽

Yongxia Li ◽

Long Pan ◽

Xuan Wang ◽

Yuqian Feng ◽

...

Keyword(s):

Parasitic Nematode ◽

Pine Wilt Disease ◽

Bursaphelenchus Xylophilus ◽

Wilt Disease ◽

Pine Forests ◽

Pinewood Nematode ◽

Dispersal Stage ◽

Pine Trees ◽

The Common ◽

Gradient Effects

AbstractPinewood nematode, Bursaphelenchus xylophilus, a pine parasitic nematode, poses a serious threat to its host pine forests globally. When dispersal-stage larvae 4 (dauer, DL4) of B. xylophilus enters the new pine, it moults into propagative adult (dauer recovery) and reproduces quickly to kill the host pine. Here, we found pine chemical volatiles, rather than the common dauer recovery factors of nematodes (e.g. suitable temperatures, nutrient availability or density), promote B. xylophilus dauer recovery. The results showed that volatilization of chemicals in host pines could attract DL4 and promote DL4 recovery. To identify which chemicals promote this process, we determined the stimulated activity of the main volatiles of pines including six monoterpenes and two sesquiterpenes. Results showed that all the six monoterpenes promoted dauer recovery, especially β-pinene and β-myrcene, but the two sesquiterpenes have no effect on the transformation. Furthermore, β-pinene performed gradient effects on dauer recovery. We hypothesized that when DL4 infect pine trees, the pine volatiles released from the feeding wounds are used as chemical signals for DL4 transformation to adult to reproduce and rapidly kill the pines. Our study identified the B. xylophilus dauer recovery chemical signal and may contribute to preventing pine wilt disease.

Download Full-text