21 research outputs found
Phytochemicals as Biopesticides against the Pinewood Nematode Bursaphelenchus xylophilus: A Review on Essential Oils and Their Volatiles
The impacts of a rapidly changing environment together with the growth in global trade
activities has promoted new plant pest pandemic events in forest ecosystems. The pinewood nematode
(PWN), Bursaphelenchus xylophilus, causes strong worldwide economic and ecological impacts.
Direct control is performed through trunk injection of powerful nematicides, however many
of these (hemi)synthetic compounds have raised ecological and human health concerns for affecting
non-target species and accumulating in food products. As sustainable alternatives, essential oils
(EOs) have shown very promising results. In this work, available literature on the direct activity of
EOs against PWN is reviewed, as a contribution to advance the search for safer and greener biopesticides
to be used in sustainable PWD pest management strategies. For the first time, important
parameters concerning the bioassays performed, the PWNs bioassayed, and the EOs used are summarized
and comparatively analyzed. Ultimately, an overview of the chemical composition of the
most active EOs allowed to uncover preliminary guidelines for anti-PWN EO efficiency. The analysis
of important information on the volatile phytochemicals composing nematicidal EOs provides
a solid basis to engineer sustainable biopesticides capable of controlling the PWN under an integrated
pest management framework and contributes to improved forest health
The genome and genetics of a high oxidative stress tolerant Serratia sp. LCN16 isolated from the plant parasitic nematode Bursaphelenchus xylophilus
In vitro co-cultures of Pinus pinaster with Bursaphelenchus xylophilus: a biotechnological approach to study pine wilt disease
Abstract
Main conclusion Co-cultures of Pinus pinaster with
Bursaphelenchus xylophilus were established as a
biotechnological tool to evaluate the effect of nematotoxics
addition in a host/parasite culture system.
The pinewood nematode (PWN), Bursaphelenchus xylophilus,
the causal agent of pine wilt disease (PWD), was
detected for the first time in Europe in 1999 spreading
throughout the pine forests in Portugal and recently in
Spain. Plant in vitro cultures may be a useful experimental
system to investigate the plant/nematode relationships in
loco, thus avoiding the difficulties of field assays. In this
study, Pinus pinaster in vitro cultures were established and
compared to in vivo 1 year-old plantlets by analyzing shoot
structure and volatiles production. In vitro co-cultures were
established with the PWN and the effect of the phytoparasite
on in vitro shoot structure, water content and
volatiles production was evaluated. In vitro shoots showed
similar structure and volatiles production to in vivo maritime
pine plantlets. The first macroscopic symptoms of
PWD were observed about 4 weeks after in vitro co-culture
establishment. Nematode population in the culture medium
increased and PWNs were detected in gaps of the callus
tissue and in cavities developed from the degradation of
cambial cells. In terms of volatiles main components,
plantlets, P. pinaster cultures, and P. pinaster with B. xylophilus
co-cultures were all b- and a-pinene rich. Cocultures
may be an easy-to-handle biotechnological approach
to study this pathology, envisioning the understanding
of and finding ways to restrain this highly
devastating nematode.
Keywords Maritime pine ! Monoxenic culture !
Pinewood nematode ! Relative water content ! Shoots
structure ! Volatiles
Abbreviations
BAP 6-Benzylaminopurine
DAI Days after inoculation
EPPO European and Mediterranean Plant Protectio
Guidelines for the reliable use of high throughput sequencing technologies to detect plant pathogens and pests
High-throughput sequencing (HTS) technologies have the potential to become one of the most significant advances in molecular diagnostics. Their use by researchers to detect and characterize plant pathogens and pests has been growing steadily for more than a decade and they are now envisioned as a routine diagnostic test to be deployed by plant pest diagnostics laboratories. Nevertheless, HTS technologies and downstream bioinformatics analysis of the generated datasets represent a complex process including many steps whose reliability must be ensured. The aim of the present guidelines is to provide recommendations for researchers and diagnosticians aiming to reliably use HTS technologies to detect plant pathogens and pests. These guidelines are generic and do not depend on the sequencing technology or platform. They cover all the adoption processes of HTS technologies from test selection to test validation as well as their routine implementation. A special emphasis is given to key elements to be considered: undertaking a risk analysis, designing sample panels for validation, using proper controls, evaluating performance criteria, confirming and interpreting results. These guidelines cover any HTS test used for the detection and identification of any plant pest (viroid, virus, bacteria, phytoplasma, fungi and fungus-like protists, nematodes, arthropods, plants) from any type of matrix. Overall, their adoption by diagnosticians and researchers should greatly improve the reliability of pathogens and pest diagnostics and foster the use of HTS technologies in plant health
In vitro co-cultures of Pinus pinaster with Bursaphelenchus xylophilus: a biotechnological approach to study pine wilt disease
Nematicidal Bacteria Associated to Pinewood Nematode Produce Extracellular Proteases
Bacteria associated with the nematode Bursaphelenchus xylophilus, a pathogen of trees and the causal agent of
pine wilt disease (PWD) may play a role in the disease. In order to evaluate their role (positive or negative to the
tree), strains isolated from the track of nematodes from infected Pinus pinaster trees were screened, in vitro, for their
nematicidal potential. The bacterial products, from strains more active in killing nematodes, were screened in order to
identify and characterize the nematicidal agent. Forty-seven strains were tested and, of these, 21 strains showed
capacity to produce extracellular products with nematicidal activity. All Burkholderia strains were non-toxic. In
contrast, all Serratia strains except one exhibited high toxicity. Nematodes incubated with Serratia strains showed, by
SEM observation, deposits of bacteria on the nematode cuticle. The most nematicidal strain, Serratia sp. A88copa13,
produced proteases in the supernatant. The use of selective inhibitors revealed that a serine protease with 70 kDa
was majorly responsible for the toxicity of the supernatant. This extracellular serine protease is different
phylogenetically, in size and biochemically from previously described proteases. Nematicidal assays revealed
differences in nematicidal activity of the proteases to different species of Bursaphelenchus, suggesting its usefulness
in a primary screen of the nematodes. This study offers the basis for further investigation of PWD and brings new
insights on the role bacteria play in the defense of pine trees against B. xylophilus. Understanding all the factors
involved is important in order to develop strategies to control B. xylophilus dispersion.This research was partially supported by Direcção Regional de Florestas, Fundo Florestal Permanente and Autoridade Florestal Nacional,
through a national project ‘O nemátode-da-madeira-do-pinheiro (NMP), Bursaphelenchus xylophilus’ and by FEDER funds through the Programa
Operacional Factores de Competitividade – COMPETE and by national funds through the Fundação para a Ciência e Tecnologia (FCT), Portugal, under
the project PTDC/AGR-CFL/115373/2009. D.N.P. was supported by FCT, Portugal, graduate fellowship SFRH/BD/61311/2009. G.P. was supported by
FCT, Portugal, fellowship PTDC/AGR-CFL/115373/2009