Summary
The aim of this review was to undertake a survey of researchers working with plant‐parasitic nematodes in order to determine a ‘top 10’ list of these pathogens based on scientific and ...economic importance. Any such list will not be definitive as economic importance will vary depending on the region of the world in which a researcher is based. However, care was taken to include researchers from as many parts of the world as possible when carrying out the survey. The top 10 list emerging from the survey is composed of: (1) root‐knot nematodes (Meloidogyne spp.); (2) cyst nematodes (Heterodera and Globodera spp.); (3) root lesion nematodes (Pratylenchus spp.); (4) the burrowing nematode Radopholus similis; (5) Ditylenchus dipsaci; (6) the pine wilt nematode Bursaphelenchus xylophilus; (7) the reniform nematode Rotylenchulus reniformis; (8) Xiphinema index (the only virus vector nematode to make the list); (9) Nacobbus aberrans; and (10) Aphelenchoides besseyi. The biology of each nematode (or nematode group) is reviewed briefly.
Two of the most damaging plant parasitic nematodes affecting vineyards in Chile are Xiphinema index and Meloidogyne ethiopica, whose control is primarily performed with chemical nematicides. The aim ...of this study was to assess the effect of formulations based on native rhizobacterial consortia and increasing cell concentrations on the mortality and root system damage of potted plants. The grapevine cultivar Cabernet Sauvignon grown in naturally infested soils was used. The isolates Bacillus amyloliquefaciens FR203A, B. megaterium FB133M, B. thuringiensis FS213P, B. thuringiensis FB833T, B. weihenstephanensis FB25M, B. frigoritolerans FB37BR, and Pseudomonas fluorescens FP805PU were initially assessed in mixtures of three, four or five bacteria in liquid, powder and isotonic solution (0.01 M MgSO4) formulations. The concentrations 106, 108 and 109 colony-forming units per mL were tested in a second study using one of the consortia. Results showed that the three initial consortia in first assay had similar effects on parasite control, with significantly lower reproductive indices observed after 6 months compared to the control. Damages caused by X. index were also lower for all the treatments, with no differences observed among the formulations. In contrast, the effects of the consortia against damages caused by M. ethiopica were more variable and did not correspond to the decrease of the juvenile densities in soil. The second assay confirmed previous results also showing that nematode control did not increase with the increasing concentrations evaluated.
•Control of nematodes in grapevines in Chile is performed primarily with chemicals.•Formulated rhizobacterial consortia may be efficient bionematicides•Consortia as liquid or powder are active at 1 × 106 colony forming units per isolate.•Populations and damages caused by X. index and M. ethiopica decrease.
Plant‐parasitic nematodes cause devastating agricultural damage worldwide. Only a few synthetic nematicides can be used and their application is limited in fields. Therefore, there is a need for ...sustainable and environment‐friendly alternatives. Nematode‐trapping fungi (NTF) are natural predators of nematodes. They capture and digest them with their hyphae and are starting to being used as bio‐control agents. In this study, we applied the NTF Arthrobotrys flagrans (Duddingtonia flagrans) against the wine pathogenic nematode Xiphinema index. A. flagrans reduced the number of X. index juveniles in pot cultures of Ficus carica, an alternative host plant for X. index, significantly. Sodium‐alginate pellets with A. flagrans spores were produced for vineyard soil inoculation under laboratory conditions. The NTF A. conoides, A. musiformis and A. superba were enriched from several soil samples, showing their natural presence. Trap formation is an energy‐consuming process and depends upon various biotic and abiotic stimuli. Here, we show that bacteria of the genus Delftia, Bacillus, Pseudomonas, Enterobacter and Serratia induced trap formation in NTF like A. conoides and A. oligospora but not in A. flagrans in the absence of nematodes. The application of NTF along with such bacteria could be a combinatorial way of efficient biocontrol in nematode‐infested soil.
Ogorčice so organizmi, ki jih zaradi njihove številčnosti, raznolikosti in prilagodljivosti najdemo praktično povsod. Medtem ko je večina ogorčic koristnih, pa poznamo tudi take, ki s svojim ...parazitiranjem povzročajo škodo. Med škodljive ogorčice uvrščamo tudi rastlinsko-parazitsko vrsto Xiphinema index. Najdemo jo lahko v bližini korenin žlahtne vinske trte (Vitis vinifera L.), saj je prav ta njena glavna gostiteljica. Ogorčica ni tako problematična z vidika neposrednega napada korenin, ampak vinski trti predstavlja grožnjo zaradi prenosa in vnosa virusa pahljačavosti listov vinske trte (GFLV) iz rodu Nepovirus. Virus namreč na vinski trti povzroči bolezen kužne izrojenosti vinske trte, kar vodi v ekonomsko nekonkurenčnost vinogradov. Okužba lahko privede tudi do več kot 80 % izpada pridelka. V izogib nenadzorovanemu širjenju ogorčic in posledično okužbam v vinogradih je pomembna preventiva, saj poleg prenosa s sadilnim materialom, pomembnega prenašalca predstavljata tudi kmetijska mehanizacija in fizični prenos z orodjem. Ker se je kemično zatiranje ogorčice X. index zaradi njene trdoživosti in razporeditve v tleh izkazalo za neučinkovito, je potrebno v prihodnje stremeti k alternativnim in predvsem učinkovitejšim pristopom. Poleg vmesnih posevkov so preverjali delovanje pripravkov na podlagi nekaterih bakterij in gliv, ki predstavljajo velik potencial za nadaljnja raziskovanja.
The ectoparasitic nematode
transmits grapevine fanleaf virus (GFLV) during feeding on grapevine roots, causing fanleaf degeneration in the plant. Hence, resistance breeding is a key to develop novel ...rootstocks to overcome such threats. In past years, various grapevine species were screened, and a few candidates with partial resistance were identified. However, they were hardly sufficient for viticulture because of their many agronomical defects. To develop reliably resistant rootstocks applicable in viticulture, multiple
spp. genotypes were analyzed using root inoculation with nematodes in glass vials as an early and easy evaluation test. Resistance levels were evaluated 35 days after inoculation based on nematode reproduction factors, focusing on juveniles and eggs. Infection of grapevines with GFLV was analyzed after inoculation with viruliferous
. With this fast screening system, putative candidates with resistances against
have been identified for future breeding programs. Particularly, genotypes with the genetic background of
and
were found to be nematode-resistant.
(GFLV) is one of the most severe virus diseases of grapevines, causing fanleaf degeneration that is transmitted by
This paper aims to isolate
species from Tunisian vineyard soil samples and assess ...their ability to acquire and transmit GFLV under natural and controlled conditions. Based on morphological and morphometric analyses, Tunisian dagger nematodes were identified as
and
These results were confirmed with molecular identification tools using species-specific polymerase chain reaction primers. The total RNA of GFLV was extracted from specimens of
and amplified based on real-time polymerase chain reaction using virus-specific primers. Our results showed that
could acquire and transmit the viral particles of GFLV. This nepovirus was not detected in
, under natural conditions; however, under controlled conditions, this nematode was able to successfully acquire and transmit the viral particles of GFLV.
The grapevine fanleaf virus (GFLV), responsible for fanleaf degeneration, is spread in vineyards by the soil nematode
. Nematicide molecules were used to limit the spread of the disease until they ...were banned due to negative environmental impacts. Therefore, there is a growing interest in alternative methods, including plant-derived products with antagonistic effects to
. In this work, we evaluated the nematicidal potential of the aerial parts and roots of four
: sainfoin (
, birdsfoot trefoil (
, sweet clover (
, and red clover (
, as well as that of sainfoin-based commercial pellets. For all tested plants, either aerial or root parts, or both of them, exhibited a nematicidal effect on
in vitro, pellets being as effective as freshly harvested plants. Comparative metabolomic analyses did not reveal molecules or molecule families specifically associated with antagonistic properties toward
, suggesting that the nematicidal effect is the result of a combination of different molecules rather than associated with a single compound. Finally, scanning electron microscope observations did not reveal the visible impact of
extract on
cuticle, suggesting that alteration of the cuticle may not be the primary cause of their nematicidal effect.
By feeding on grapevine roots, the ectoparasite
Xiphinema index
transmits grapevine fanleaf virus (GFLV), causing fanleaf degeneration in the plant. Therefore, rootstock breeding programs are ...considered a key to resistance to both threats. Previous screening depends on long-lasting inoculation experiments and mainly focuses on evaluating gall formation on the parasitized roots to identify potential resistance in grapevines. Since the roots of grapevine rootstocks resistant to
X. index
and even those of susceptible cultivars showed no reliable gall formation after parasitism, and further, root thickening was regularly found on non-inoculated control plants, nematode reproduction rates were used to validate rootstock phenotypes regarding susceptibility or resistance to
X. index
. For our approach, a glass vial assay was performed, and 35 days after inoculation the nematode population was determined by counting juveniles after the extraction. Reproduction rates were high on susceptible rootstock cultivars and decreased the more resistant a cultivar is considered. Besides focusing solely on root gall formation, the nematode reproduction rate should be included as a reliable indicator for resistance screening. The described assay setup enables the evaluation of resistance levels by fast screening to select promising rootstock candidates.
The ectoparasitic dagger nematode (Xiphinema index), vector of Grapevine fanleaf virus (GFLV), provokes gall formation and can cause severe damage to the root system of grapevines. Mycorrhiza ...formation by Glomus (syn. Rhizophagus) intraradices BEG141 reduced both gall formation on roots of the grapevine rootstock SO4 (Vitis berlandieri×V. riparia) and nematode number in the surrounding soil. Suppressive effects increased with time and were greater when the nematode was post-inoculated rather than co-inoculated with the arbuscular mycorrhizal (AM) fungus. Using a split-root system, decreased X. index development was shown in mycorrhizal and non-mycorrhizal parts of mycorrhizal root systems, indicating that both local and systemic induced bioprotection mechanisms were active against the ectoparasitic nematode. Expression analyses of ESTs (expressed sequence tags) generated in an SSH (subtractive suppressive hybridization) library, representing plant genes up-regulated during mycorrhiza-induced control of X. index, and of described grapevine defence genes showed activation of chitinase 1b, pathogenesis-related 10, glutathione S-transferase, stilbene synthase 1, 5-enolpyruvyl shikimate-3-phosphate synthase, and a heat shock proein 70-interacting protein in association with the observed local and/or systemic induced bioprotection against the nematode. Overall, the data suggest priming of grapevine defence responses by the AM fungus and transmission of a plant-mediated signal to non-mycorrhizal tissues. Grapevine gene responses during AM-induced local and systemic bioprotection against X. index point to biological processes that are related either to direct effects on the nematode or to protection against nematode-imposed stress to maintain root tissue integrity.
The nematicidal activity of fluensulfone against
Xiphinema index
and
Longidorus vineacola
was compared to that of organophosphate and carbamate nematicides. The number of
X. index
recovered via ...Baermann funnel from infested soil treated with fenamiphos or cadusafos at 2.0 and 4.0 mg l
−1
soil was higher than that recovered from untreated infested soil. The number of recovered
X. index
after fluensulfone treatment at these concentrations reflected the same level of that recovered from the control soil; however, a high percentage of the nematodes were immobilized after extraction. In experiments using fig plants in pots, the
X. index
population was much lower after treatment with fluensulfone vs. fenamiphos. Moreover, the nematode control efficacy of fluensulfone against
X. index
was much higher by pre-planting vs. post-planting application. Treatment of
L. vineacola
-infested soil with fluensulfone at 2.0 and 4.0 mg l
−1
soil slightly reduced the number of recovered nematodes in one of two trials, whereas fenamiphos and cadusafos did not reduce, and sometimes even increased the number of nematodes recovered from the soil. The nematode control efficacy of fluensulfone against
L. vineacola
was much higher than that of fenamiphos or oxamyl in pots with pepper plants. Again, pre-planting application of fluensulfone was more effective at reducing the
L. vineacola
population than post-planting application. The results suggest that fluensulfone can effectively control
Xiphinema
and
Longidorus
in the field, especially by pre-planting treatment.
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