The combined use of Pochonia chlamydosporia and plant defence activators - a potential sustainable control strategy for Meloidogyne chitwoodi

Sustainable strategies are required for control of the root-knot nematode Meloidogyne chitwoodi to reduce dependence on toxic chemical pesticides. The efficacy of the nematophagous fungus Pochonia chlamydosporia in biocontrol could be enhanced by integration with control measures that reduce initial nematode infestations. The use of foliar sprays with plant defence activators can reduce the susceptibility of potato plants to M. chitwoodi. This study assessed effects of combined soil application of P. chlamydosporia with foliar sprays of benzothiadiazole (BTH) or cis-jasmone on infection of potatoes by M. chitwoodi. Solanum tuberosum, cv. Désirée plants were grown in soil mixed with 5000 chlamydospores g-1 of soil, sprayed twice with BTH or cis-jasmone and inoculated with 300 M. chitwoodi second-stage juveniles. Forty-five days after inoculation, nematode reproduction, numbers of colony-forming units of the fungus g-1 of soil and g-1 of root, and egg parasitism were assessed by standard techniques. Foliar sprays of BTH or cis-jasmone combined with the fungus reduced nematode reproduction (P<0.05, LSD). The presence of the fungus slightly increased the efficacy of cis-jasmone, as the number of eggs per egg mass was less in plants treated both with cis-jasmone and the fungus than in the plants treated only with the defence activator. The proportion of parasitized eggs was greater in the cis-jasmone treatment where rhizosphere colonisation was less, suggesting that P. chlamydosporia became a poorer rhizosphere coloniser but a more efficient nematode parasite. The addition of P. chlamydosporia to soil in combination with application of inducers of plant defence could be an alternative control strategy to be used against M. chitwoodi in potato

Inoculum levels of Meloidogyne hispanica and M. javanica affect nematode reproduction, and growth of tomato genotypes

A pot experiment was conducted to determine the effects of three inoculum levels (2,500, 5,000 and 10,000 eggs/plant) on the reproduction of Meloidogyne hispanica and M. javanica isolates and growth of the susceptible tomato genotypes Easypeel and Moneymaker, and genotypes Motelle and VFnt-Cherr, which possess the Mi-gene, at 25±2°C. sixty days after inoculation, roots were assessed for gall index (Gi), reproduction factor (Rf=final/initial population density) and reproduction index (RI=Rf in the Mi-gene tomato plants/Rf in tomato Easypeel × 100). shoot and root lengths and fresh and dry root and shoot weights were also recorded. both species of Meloidogyne reproduced at all inoculum levels on all four tomato genotypes (4≤GI≤5 and 3.44≤Rf≤317.30). The M. javanica isolate, obtained from an infected potato field, was identified as natural and partially virulent to the Mi-gene (3.71≤RI≤20.19). This emphasizes the need for new sources of resistance to root-knot nematodes and for testing Mi-tomato plants for their susceptibility to local populations. Reproduction of M. javanica and M. hispanica on the resistant Motelle and VFNT-Cherr was significantly less than on the susceptible Easypeel and Moneymaker. VFNT-Cherr was more resistant than Motelle, which suggest an influence of the genetic background of the plants on the nematode response. For Easypeel and Moneymaker, there was a trend of decreased plant growth parameters with increasing inoculum level, irrespective of the nematode species, due to damage caused by the increasing number of nematodes that invaded plant roots. However, these values on Motelle and VFnt-Cherr remained relatively stable regarding shoot and total shoot plus root dry weight. the reproductive rate of M. javanica was greater than that of M. hispanica on all four genotypes tested, and tomato plants inoculated with M. hispanica had greater growth parameters. the resistance response of the Mi-tomato plants was independent of the Meloidogyne species, however, because both species gave similar Ris

Imunolocalização de produtos secretados-excretados de Meloidogyne spp. usando anticorpos policlonais e monoclonais

Moléculas expressadas na cutícula dos nematóides parasitas de plantas representam o primeiro contato planta-nematóide e, junto com produtos secretados/excretados (S-E), são, provavelmente, os primeiros sinais percebidos pelo hospedeiro. Essas moléculas, as quais são liberadas dentro do tecido da planta, podem ter papel importante na interação parasita-hospedeiro. A caracterização desses antígenos pode ajudar na identificação de alvos para novas estratégias que interfiram na infecção de plantas por nematóides. Três anticorpos monoclonais e três anticorpos policlonais produzidos para secreções-excreções de Meloidogyne spp. e Heterodera avenae foram usados para examinar a reatividade a juvenis de segundo estádio (J2) e/ou fêmeas de M. incognita e M. arenaria. Os três anticorpos policlonais mostraram reação tanto para M. incognita quanto para M. arenaria. Roth-PC 373 reconheceu fortemente moléculas presentes na cutícula, anfídios e intestino, Roth-PC 389 reconheceu anfidios e metacorpo, enquanto Roth-PC 419 ligou-se a moléculas presentes nas glândulas subventrais. A reatividade dos MAbs foi testada somente com M. Arenaria. Roth-MAb T116C1.1 reagiu intensamente com moléculas presentes nas glândulas anfidial e fasmidial. Roth-MAb T46.2 e T42D.2 marcaram anfídios e moléculas presentes no esôfago (metacorpo) do nematóide, respectivamente.Molecules expressed at the surface cuticle (SC) of plant parasitic nematodes represent the primary plant-nematode interface, and together with secreted-excreted (S-E) products are probably the first signals perceived by the host. These molecules, which are released into plant tissue, probably play important roles in the host-parasite interactions. Characterisation of these antigens will help in the identification of nematode targets useful for novel control strategies, which interfere with the nematode infection of plants. Three monoclonal (MAbs) and three polyclonal (PAbs) antibodies produced to S-E products of Meloidogyne spp. and Heterodera avenae were used to examine their reactivity towards M. incognita and/or M. arenaria second stage juveniles and adult females. The three PAbs showed cross-reactivity with M. incognita and M. arenaria. Antibody Roth-PC 373 strongly recognised molecules present in the SC, amphids and intestine, antibody Roth-PC 389 recognised the nematode amphids and metacorpus, while antibody Roth-PC 419 bound to molecules present in the subventral glands. Reactivity of the MAbs was only tested against M. arenaria. Monoclonal antibody Roth-MAb T116C1.1 showed intense reactivity with molecules present in the amphidial and phasmidial glands. Monoclonal antibodies Roth-MAb T46.2 and T42D.2 labeled the nematode amphids and molecules present in the nematode oesophagus (metacorpus), respectively

Cuticle Surface Coat of Plant-Parasitic Nematodes

The surface coat (SC) of the plant-parasitic nematode cuticle is an understudied area of current research, even though it likely plays key roles in both nematode-plant and nematode-microbe interactions. Although in several ways Caenorhabditis elegans is a poor model for plant-parasitic nematodes, it is a useful starting point for investigations of the cuticle and its SC, especially in the light of recent work using this species as a model for innate immunity and the generic biology underpinning much host-parasite biology. We review the research focused on the involvement of the SC of plant-parasitic nematodes. Using the insights gained from animal-parasitic nematodes and other sequenced nematodes, we discuss the key roles that the SC may play