Susceptibility evaluation of Picea abies and Cupressus lusitanica to the pine wood nematode (Bursaphelenchus xylophilus)

Abstract

Pine wilt disease (PWD), recently introduced into Europe, is caused by the pine wood nematode (PWN) Bursaphelenchus xylophilus and is a devastating illness that affects mainly pine trees. It is known that the PWN is capable of infecting other conifers; however, there is currently no information on which other plant species may be susceptible to PWD. In this study, the potential susceptibility of two common species of European forests, Picea abies and Cupressus lusitanica, to PWN was assessed through the monitoring of visual external symptoms, dimension and localization of the nematode population in stems, quantification of total chlorophyll, total soluble phenolics and lignin, at 7, 14, 21 and 28 days after inoculation. The degree of susceptibility was established through the comparison of symptoms with Pinus pinaster, a well-known PWN host. Furthermore, the stem ultrastructure of P. abies, C. lusitanica and Pn. pinaster was analysed by scanning electron microscopy. The results suggest that P. abies and C. lusitanica are resistant to PWN, and that lignin biosynthesis in these species is affected at an early stage of the infestation. Nevertheless, P. abies seems to be a compatible host that could act as a repository for PWN.

Intraspecific variation of anatomical and chemical defensive traits in Maritime pine (Pinus pinaster) as factors in susceptibility to the pinewood nematode (Bursaphelenchus xylophilus)

“…We found a positive relationship between nematode migration and polyphenol concentration of branch segments, contradicting previous research reporting that PWN resistant species or varieties accumulate more phenolic compounds than susceptible ones in response to PWN infection (Kuroda et al 2011;Nunes da Silva et al 2013). Some particular phenolic compounds found in resistant pine species, i.e., stilbenoids, have been reported to show nematicidal activity to the PWN in in vitro assays (Suga et al 1993), although their role as a factor of resistance in vivo has been questioned (Zhang et al 2013).…”

“…Moreover, nematode migration has been related to the virulence of the PWN (Kuroda 2008b;Son et al 2010). In particular, nematode migration has been found to be slower or even completely blocked in resistant conifer species (Oku et al 1989;Nunes da Silva et al 2013), and in resistant genetic variants (Kuroda 2004;Kuroda et al 1991). Some examples that contradicted this were also reported, however, indicating that migration and colonization ability do not completely determine the susceptibility of pines to the PWN (Mori et al 2008;Eo et al 2011).…”

Chitosan as a biocontrol agent against the pinewood nematode (Bursaphelenchus xylophilus)

“…The loss of photosynthetic pigments can occur from an early stage of the PWD and can be used to assess the degree of tissue damage caused by B. xylophilus (Nunes da Silva et al. ). In the current work, in the absence of chitosan, 24 dai both P. pinaster and P. pinea PWN‐inoculated plants experienced a decrease in total chlorophylls (Fig.…”

“…1000 PWNs using the technique described by Nunes da Silva et al. (). In addition, 80 plants of each species (20 for each chitosan solution and 20 controls) were inoculated with deionized water.…”

Chitosan and chitooligosaccharide utilization in phytoremediation and biofortification programs: current knowledge and future perspectives

“…Both molecules are known to induce the biosynthesis of several antimicrobial compounds, namely phytoalexins (Vasyukova et al, 2001), callose (Ren et al, 2001) and lignin (Barber et al, 1989). Several papers have reported that chitosans and CHOs can be used, for example, to enhance the plant's defense against bacteria (Tikhonov et al, 2006; Rabea and Steurbaut, 2010), fungi (Park et al, 2002; Trotel-Aziz et al, 2006) and nematodes (Khalil and Badawy, 2012; Nunes da Silva et al, 2014). Besides plant defense, a broader range of influences in plant growth and development have been shown.…”