Meloidogyne Incognita Research Articles

Vermicomposting of Pleurotus eryngii spent mushroom substrates and the possible mechanisms of vermicompost suppressing nematode disease caused by Meloidogyne incognita

The mushroom industry produces a large amount of spent mushroom substrate (SMS), which requires a large geographical footprint and causes pollution. Vermicomposting is a low-cost technology for its value in recycling of organic wastes and production of beneficial organic fertilizers. In this study, the changes of physicochemical properties was characterized during vermicomposting of Pleurotus eryngii SMS with cow dung (CD) as amendment. The efficiency and possible mechanisms of vermicompost suppressing disease induced by Meloidogyne incognita was also investigated. Six combinations with different ratios of SMS and cow dung (CD) was included in the vermicomposting using Eisenia fetida. Effect of vermicompost against disease induced by M. incognita on tobacco was conducted under greenhouse condition. And the possible mechanisms of vermicompost suppressing M. incognita was investigated by evaluated the species diversity of nematode-trapping fungi (NTF) in soil, and the defense response enzymes in tobacco. The combination of 65% SMS +35% CD was more suitable for vermicomposting, in which the highest vermicompost production (57%) and earthworm biomass increment (268%) were achieved. Additionally, the reduction in pH, total organic carbon, carbon: nitrogen ratio, and the pronounced elevation in four overall nutrient status were also observed. Soil amended with vermicompost (100:1 w/w) showed 61% control efficiency against nematode disease caused by M. incognita on tobacco, which significantly higher than that of the normal compost (24%). Comparing to the normal compost, the potential mechanism of vermicompost suppressing M. incognita could be rely on promoting species diversity of NTF in soil and enhancing the activities of the defense response enzymes in tobacco plant. Our findings indicate that vermicomposting is a promising technology for recycling of P. eryngii SMS, and the resulting vermicompost as organic fertilizer can be sued for management of the diseases caused by root-knot nematodes. This study establish a sustainable avenue for P. eryngii SMS disposal and a practical manner for controlling pathogens.

Screening of Psidium species and their interspecific hybrid progenies for resistance to Fusarium oxysporum f. sp. psidii and southern root-knot nematode

Screening of Psidium species and their interspecific hybrid progenies for resistance to Fusarium oxysporum f. sp. psidii and southern root-knot nematode

Effect of Some Nematicides on Hatching Eggs and Viability of Second Stage Juveniles of Root-Knot Nematode, Meloidogyne Incognita Under Laboratory Conditions

This study was conducted to evaluate the efficacy of three nematicides, Blue Guard, Garland garlic extract, Nema-kill at two concentrations of 50 and 100ppm in inhibiting egg hatching and killing second stage juveniles of root-knot nematode, M. incognita under laboratory conditions. The results showed the effectiveness of nematicides in inhibiting eggs and killing juveniles with significant differences compared with control treatments. Garland garlic extract 100ppm achieved the highest inhibition rate of 94.4% compared with nematicides, blue guard 100ppm and Nema-kill 100ppm, which amounted to 65.6 and 60.2%, respectively, after 7 days compared with control treatment 4.2%. The results also showed significant differences in the killing of juveniles by the superiority of the Garland garlic extract 100 ppm, which achieved the highest killing rate of juveniles that reached 88.4% compared with treatments of the pesticide, blue guard 100 ppm and Nema-kill 100 ppm, which amounted to 59.2 and 58%, respectively, after 4 days.

Comparative chemical composition and pesticidal evaluation of Acorus calamus accessions collected from different geographical locations

The objectives of the present study were to investigate the phytochemical composition of essential oils (EO) from rhizomes of Acorus calamus collected from Jorhat, Assam; Munsyari and Pantnagar, Uttarakhand, India. EOs were studied for different pesticidal activities viz; nematicidal, insecticidal, and herbicidal activity. To study the synergistic effect of EOs on pesticidal activity, four combinations of EOs were prepared. Phenylpropanoids with β-asarone as the main compound were identified in all collections with varying percentages. Its contribution was found to be 85.8% in Munsyari EOs followed by 74.3% in Pantnagar and 62.6% in Assam collections. All EOs exhibited dose-dependent in vitro nematicidal activity against Meloidogyne incognita in terms of immobility and inhibition of egg hatching. The activity was observed as maximum in the EO combination of all three collections (1:1:1) whereas minimum in the Assam collections. In insecticidal activity against Lipaphis erysimi and Selepa celtis, maximum mortality was observed in Munsyari collections. The oils were assessed for sprout inhibition activity in terms of seed germination inhibition, coleoptile growth of the shoot and root against Raphanus raphanistrum. Maximum seed germination inhibition, % shoot, and root growth inhibition were found in all collections EO combinations. To predict the possible mode of action and the structure-activity relationship between major compounds of EOs and biological activities, in silico molecular docking and ADME/Tox studies were performed. The docking results revealed the mode of action of proteins of insects, nematodes, and weeds and were found in support of in vitro experiments. The study may be helpful for the development of herbal-based pesticides after proper clinical trials.

Biological and Physiological Responses of Root-knot Disease Development on Five Cucurbits Exposed to Different Concentrations of Sulfur Dioxide.

A study was undertaken in order to investigate the effects of SO2 (25, 50, and 75 ppb) exposure for five hours on alternate days for three months on the susceptibility of five cucurbits to the infection of Meloidogyne incognita, causing root-knot disease. Four-week-old cucurbit plants were inoculated with 2000 J2 of M. incognita. SO2 levels of 50 and 75 ppb caused noticeable injury to foliage and reduced the plant growth parameters and biomass production of cucurbits (p ≤ 0.05). Nematode-inoculated plants caused characteristic oval, fleshy and large galls. The galls were formed closely, and as a result they coalesced, giving bead-like impressions especially in pumpkin and sponge gourds. Disease severity became aggravated on plants exposed to SO2 at 50 or 75 ppb concentrations. The nematode and SO2 interaction varied with the levels of SO2 and the response of the plant to M. incognita. SO2 at 50 or 75 ppb concentrations stimulated the pathogenesis of M. incognita on cucurbit species. The combined effect of 75 ppb SO2 and M. incognita suppressed plant length by 34% against the sum of decreases observed by M. incognita and SO2 individually (14-18%). At 50 ppb SO2, the fecundity of M. incognita was decreased and combined effect of SO2 and M. incognita was more than the sum of their singular effects. The study has proven that root-knot disease might become aggravated in the regions contaminated with elevated levels of SO2.

Introduction pages, NBHA-CN 51(1), 2023

The papers published in Notulae Botanicae Horti Agrobotanici Cluj-Napoca, Issue 1, Volume 51, 2023 represent new exciting research in different topics of life science, respectively in plant science, horticulture, agronomy, and crop science. Among the interesting articles we invite you to find news about: Climate change, its impact on crop production, challenges, and possible solutions; The use of phytotherapy in hepatocellular carcinoma – a systematic review; Anticancer effects of Rhinacanthus nasutus and Acanthus ebracteatus extracts against human cervical cancer cells; Iodine application in Vitis vinifera L. cv. ‘Cabernet Sauvignon’ improve bioactive compounds and enzymatic activity in berries; Arbuscular mycorrhizal fungi promote photosynthesis in Antirrhinum majus L. under low-temperature and weak-light conditions; Biocontrol of the root-knot nematode Meloidogyne incognita with Purporeocillum lilacinum and liquid bio-formulates in tomato (Solanum lycopersicum); Impacts of heat shock on productivity and quality of Triticum aestivum L. at different growth stages.

Potentials of Artocarpus altilis latex lectin (AaLL) as an antiproliferative, nematicidal, and insecticidal agent

Introduction and Aim: Plants are the most accessible and convenient source of lectins. Artocarpus altilis is a Moraceae plant utilized for its latex. The anti-proliferative, nematicidal, and insecticidal effects of this plant latex are unknown. The current study evaluates the antiproliferative, nematicidal, and insecticidal activity of pure AaLL on Triple Negative Breast Cancer cells, Meloidogyne incognita, and Spodoptera frugiperda, respectively.
 
 Materials and Methods: To assess AaLL's antiproliferative activity against MDA-MB-231, MTT and wound healing experiments were performed. Using juvenile mortality and feeding assays, the in vitro nematicidal and insecticidal activity against Meloidogyne incognita and Spodoptera frugiperda were evaluated.
 
 Results: The MTT experiment demonstrated that 5.4µg/ml AaLL effectively inhibited MDA-MB-231 growth by 50% compared to the control. Even at 40µg/ml, AaLL had no cytotoxic effects on NIH3T3 fibroblast cells. AaLL significantly reduced cell migration, with the wound area remaining at 41.95 percent as opposed to 4.57 percent in the control group. In vitro results on J2s exposed to AaLL for 72 hours demonstrated a death rate of 52% at a concentration of 30µg/ml. After 24 hours of incubation with 400µg/ml lectin, the insecticidal tests reveal that AaLL considerably reduces the weight of larvae. After 48 hours, a lectin concentration of 0.04% caused 69.44% larval death.
 
 Conclusion: This is the first report demonstrating the latex lectin from Artocarpus altilis's anti-proliferation, anti-migration, nematicidal, and insecticidal properties. Further research will be done on the signaling pathways and mechanism of action linked to these features.

Grass-Shaped Zinc Oxide Nanoparticles Synthesized by the Sol-Gel Process and Their Antagonistic Properties towards the Biotrophic Parasite, Meloidogyne incognita.

The presence of Meloidogyne spp., also known as root-knot nematodes, presents a significant danger to global agricultural progress. Since chemical nematicides have high levels of toxicity, it is imperative to develop environmentally friendly methods to manage root-knot nematodes. Nanotechnology is now the most progressive way to attract researchers due to its innovative quality in combating plant diseases. Our study focused on the sol-gel process to synthesize grass-shaped zinc oxide nanoparticles (G-ZnO NPs) and assess its nematicidal behavior against Meloidogyne incognita. Various concentrations (250, 500, 750, and 1000 ppm) of G-ZnO NPs were utilized to expose both the infectious stage (J2s) and egg masses of M. incognita. Laboratory results revealed that G-ZnO NPs showed toxicity to J2s with LC50 values of 1352.96, 969.64, and 621.53 ppm at 12, 24, and 36 hours, respectively, and the result was the inhibition of egg hatching in M. incognita. All three exposure periods were reported linked with the concentration strength of G-ZnO NPs. The pot experiment results exhibited that G-ZnO NPs significantly reduced the root-gall infection of chickpea plants under M. incognita attack. Compared with the untreated control, there was a significant improvement in plant growth attributes and physiological parameters as well, when distinct G-ZnO NP doses (250, 500, 750, and 1000 ppm) were applied. In the pot study, we noticed a reduction in the root-gall index with an increase in the concentration of G-ZnO NPs. The results confirmed that G-ZnO NPs have enormous potential in sustainable agriculture for controlling the root-knot nematode, M. incognita, in chickpea production.

Purpureocillium lilacinum for plant growth promotion and biocontrol against root-knot nematodes infecting eggplant.

Purpureocillium lilacinum is a biocontrol Ascomycota fungus against various plant pathogens. In the present study, the efficacy of P. lilacinum was evaluated against a root-knot nematode, Meloidogyne incognita that infects eggplants. We performed an in vitro experiment in which the direct effects of P. lilacinum on the second-stage juvenile survival and egg hatching of M. incognita were tested at different exposure times. The results showed that P. lilacinum significantly reduced the rates of egg hatching and juvenile survival in a dose-dependent manner. Microscopic observation demonstrated that P. lilacinum directly penetrated the eggs and contacted the juveniles, indicating how P. lilacinum parasitizes M. incognita. We also performed a pot assay in which soil-grown eggplants were treated with P. lilacinum followed by inoculation with M. incognita. The results indicated that P. lilacinum effectively reduced the nematode population and the number of galls in plant roots. Interestingly, application of P. lilacinum resulted in significant enhancements in plant growth and biomass, even under nematode infection, while it improved plant photosynthetic pigments, i.e., chlorophyll and carotenoids. Taken together, our study suggested that P. lilacinum can be used as a plant growth-promoting fungus and a biological nematicide for disease management of root-knot nematodes in eggplants.

Non-host plant odors influence the tritrophic interaction between tomato, its foliar herbivore Tuta absoluta and mirid predator Nesidiocoris tenuis.

The tomato leafminer, Tuta absoluta is a destructive invasive pest of cultivated tomato and other Solanaceae plants, with yield losses of 80-100%. Mirid predators are key natural enemies of T. absoluta, but they also feed on host plants in the absence of their prey. Management of T. absoluta is a challenge due to its high biotic potential, resistance to many insecticides and the absence of sufficiently adapted auxiliary fauna in its new dispersion zones. Olfaction plays an important role in the tritrophic interaction between tomato, its herbivore pest T. absoluta and its mirid predators, which can be influenced by non-host plant odors. However, how non-host odours shape this interaction is poorly understood. Previously, we had demonstrated belowground crop protection properties of certain Asteraceae plants against the root-knot nematode Meloidogyne incognita, pest of tomato and other Solanaceae plants. Additionally, Asteraceae plants impact negatively on feeding behavior of above-ground pests of Solanaceae plants, including the greenhouse whitefly (Trialeurodes vaporariorum) and green peach aphid (Myzus persicae). Here, we tested the hypothesis that foliar volatiles from some of these non-host Asteraceae plants can influence the tomato-T. absoluta-mirid predator tritrophic interaction. In olfactometer assays, T. absoluta females were attracted to volatiles of the Solanaceae host plants tomato and giant nightshade but avoided volatiles of the Asteraceae plants, blackjack and marigold, and the positive control, wild tomato, when tested alone or in combination with the host plants. Coupled gas chromatography-mass spectrometry analysis showed that host and non-host plants varied in their emission of volatiles, mainly monoterpenes and sesquiterpenes. Random forest analysis combined with behavioral assays identified monoterpenes as the host plant attractive blend to T. absoluta and its mirid predator, with sesquiterpenes identified as the non-host plant repellent blend against T. absoluta. Contrastingly, the mirid predator was indifferent to the non-host plant repellent sesquiterpenes. Our findings indicate that terpenes influence the tomato-T. absoluta-mirid predator tritrophic interaction. Further, our results emphasize the importance of studying crop protection from a holistic approach to identify companion crops that serve multi-functional roles.

Evaluation of some grape rootstocks for resistance to root– knot nematode (Meloidogyne incognita) and reflection on vegetative, chemical characters, root density and distribution

Evaluation of some grape rootstocks for resistance to root– knot nematode (Meloidogyne incognita) and reflection on vegetative, chemical characters, root density and distribution

Alleviation of Meloidogyne incognita induced biotic stress in Daucus carota by nitrogen: Insights into cellular viability and reactive oxygen species of the host

Developing innovative nematode management solutions is becoming more important since ecologically hazardous nematicides are being phased out of the global markets. As a result, alternative measures that are less harmful to the environment are preferred for dealing with the root-knot nematodes which cause huge economic losses to farmers. This investigation was therefore, entailed to find the optimum nitrogen fertilizer rate to maximize plant growth promotion and upsurge nematicidal activity, while minimizing the harmful effects on environment. Among the various nitrogen fertilizer treatments from 50 kg/ha to 200 kg/ha, the most effective concentration was found to be 150 kg/ha N (U150Mi) at which significant (P ≤ 0.05) improvements in growth, yield, photosynthetic pigments, nitrate reductase activity (NRA), protein, and carbohydrate content of carrot were observed as compared to the nematode inoculated untreated plants. Scanning electron microscopy showed that compared to the untreated inoculated control, the stomatal characteristics of carrot improved significantly at U150Mi (150 kg/ha N). Laser confocal microscopy illustrated that nitrogen fertilizer markedly improved the cellular viability of carrot at U150Mi (150 kg/ha N) in comparison to nematode infected plants. Histochemical analysis revealed that the reactive oxygen species (ROS) marker, superoxide anion radicals were significantly scavenged by the enhanced antioxidant defense system of carrot at U150Mi (150 kg/ha N). In vitro studies demonstrate that nitrogen fertilizer has nematicidal properties that were dose dependent. Gall/egg mass indices and reproduction factor were dramatically reduced when U150Mi (150 kg/ha N) was applied to carrot plants inoculated with Meloidogyne incognita.

Comparative efficacy of zirconium dioxide nanoparticles and AM fungus against wilt disease complex of bottle gourd and upregulation of biochemical and physiological processes

ABSTRACT The disease complex affecting bottle gourd [Lagenaria siceraria (Mol.) Standl.] caused by Meloidogyne incognita and Fusarium oxysporum results in high yield loss and there is a need for their management. Nanoparticles (NPs) and arbuscular mycorrhizae have potential in disease management. The impacts of 0.10 g.L−1 zirconium dioxide nanoparticles (ZrO2 NPs) (applied as foliar spray or seed priming) and AM fungus Rhizophagus irregularis were determined when applied alone, or in combination, on the disease complex of bottle gourd. Use of ZrO2 NPs as seed priming and foliar application increased plant growth and photosynthetic pigments and reduced disease indices, galling and population of M. incognita. Foliar application of ZrO2 NPs increased plant growth and photosynthetic pigments and reduce disease indices, galling, and population of M. incognita than did seed priming. Use of R. irregularis alone resulted in lessened plant growth and photosynthetic pigments than NPs foliar application alone. Use of R. irragularis with NPs foliar application was best for management of disease complex of bottle gourd than its use as seed priming. Wilt disease indices were rated 1–5. Use of R. irregularis/NPs reduced disease incidence, and disease indices were reduced to 1 in treatment where R. irragularis was used with ZrO2 NPs. Root colonization by R. irragularis was similar when used alone or with NPs. Inoculation of pathogens reduced colonization by R. irregularis. Management of the disease complex of bottle gourd may be achieved by use of 500 infective propagules of R. irragularis with 0.10 g.L−1 ZrO2 NPs foliar application.

Tomato defence against Meloidogyne incognita by jasmonic acid-mediated fine-tuning of kaempferol homeostasis.

Jasmonic acid (JA) is involved in the modulation of defence and growth activities in plants. The best-characterized growth-defence trade-offs stem from antagonistic crosstalk among hormones. In this study, we first confirmed that JA negatively regulates root-knot nematode (RKN) susceptibility via the root exudates (REs) of tomato plants. Omics and toxicological analyses implied that kaempferol, a type of flavonol, from REs has a negative effect on RKN infection. We demonstrated that SlMYB57 negatively regulated kaempferol contents in tomato roots, whereas SlMYB108/112 had the opposite effect. We revealed that JA fine-tuned the homeostasis of kaempferol via SlMYB-mediated transcriptional regulation and the interaction between SlJAZs and SlMYBs, thus ensuring a balance between lateral root (LR) development and RKN susceptibility. Overall, this work provides novel insights into JA-modulated LR development and RKN susceptibility mechanisms and elucidates a trade-off model mediated by JA in plants encountering stress.

Efficacy of Azadirachtin in the Integrated Management of the Root Knot Nematode Meloidogyne incognita on Short- and Long-Cycle Crops

Activity of azadirachtin on phytoparasitic nematodes has been documented for some decades, but the relationship between its nematicidal efficacy and crop cycle length has not yet been clarified. This study aimed to assess the efficacy of an azadirachtin-based nematicide, for controlling the infestation of the root-knot nematode Meloidogyne incognita, on the short- and long-cycle crops, lettuce and tomato, respectively. Experiments on lettuce and tomato were carried out in a greenhouse infested by M. incognita, including non-treated soil, or treated with the nematicide fluopyram, as controls. In the experiment on the short-cycle lettuce crop, the azadirachtin product effectively suppressed M. incognita infestation and increased crop yield, without significant differences from fluopyram. In the tomato crop, both azadirachtin and fluopyram were not able to control nematode infestation, but resulted in significantly higher yields. Data from this study indicated that azadirachtin can be a valid alternative to fluopyram and other nematicides, for root-knot nematode control in short-cycle crops. Integration of azadirachtin with a synthetic nematicide or nematode-suppressive agronomical techniques, should be more suitable to long-cycle crops.

Crop rotation with Meloidogyne-resistant germplasm is useful to manage and revert the (a)virulent populations of Mi1.2 gene and reduce yield losses.

A rotation sequence of ungrafted and grafted tomato-melon-pepper-watermelon on resistant rootstocks 'Brigeor', Cucumis metuliferus, 'Oscos' and Citrullus amarus, respectively, was carried out in a plastic greenhouse, ending with a susceptible or resistant tomato crop. The rotation was conducted in plots infested by an avirulent (Avi) or a partially virulent (Vi) Meloidogyne incognita population to the Mi1.2 gene. At the beginning of the study, the reproduction index (RI, relative reproduction in the resistant respect susceptible tomato) of Avi and Vi populations was 1.3% and 21.6%, respectively. Soil nematode density at transplanting (Pi) and at the end (Pf) of each crop, disease severity and crop yield were determined. Moreover, the putative virulence selection and fitness cost were determined at the end of each crop in pot tests. In addition, a histopathological study was carried out 15 days after nematode inoculation in pot test. The volume and number of nuclei per giant cell (GC) and the number of GC, their volume and the number of nuclei per feeding site in susceptible watermelon and pepper were compared with C. amarus and resistant pepper. At the beginning of the study, the Pi of Avi and Vi plots did not differ between susceptible and resistant germplasm. At the end of the rotation, the Pf of Avi was 1.2 the Pi in susceptible and 0.06 in resistant, the cumulative yield of grafted crops was 1.82 times higher than that of the ungrafted susceptible ones, and the RI in resistant tomato less than 10% irrespective of the rotation sequence. Concerning the Vi, Pf was below the detection level at the end of the rotation in resistant and 3 times Pi in the susceptible. The cumulative yield of grafted crops was 2.83 times higher than that of the ungrafted and the RI in resistant tomato was 7.6%, losing the population's virulence. In the histopathological study, no differences in number of GC per feeding site were observed in watermelon compared to C. amarus, but they were more voluminous and contained higher number of nuclei per GC and per feeding site. Regarding pepper, Avi population did not penetrate resistant rootstock.

Effect of the southern root-knot nematode on white pitahaya growth

Effect of the southern root-knot nematode on white pitahaya growth

Arbuscular mycorrhizal fungus species differed in bio-control potential on pepper genotypes infected with Meloidogyne incognita

ABSTRACT Root-knot nematode Meloidogyne spp. causes galls on pepper (Capsicum spp L.) roots leading to yield loss. Root-knot disease control in pepper with chemical nematicides is effective but environmental and health concerns are serious drawbacks. Use of arbuscular mycorrhizal fungi (AMF) for control may present a solution. A screenhouse experiment was conducted to assess bio-control efficacy of 4 AMF species against Meloidogyne incognita infecting pepper genotypes with known resistance. Septoglomus deserticola and Funneliformis mosseae were the most efficient (p = .05) AMF species in inhibiting nematode infection, enhancing growth and fruit yield of pepper genotypes. Averaged across pepper genotypes, S. deserticola increased fresh fruit yield by 2.42% and 6.98% compared with Claroideoglomus claroideum and Gigaspora gigantea, respectively, while F. mosseae increased it by 1.43% and 5.95%, respectively. These AMF species might be used as bio-control agents of M. incognita infecting these pepper genotypes.

Sulfoxide-Containing Bisabolane Sesquiterpenoids with Antimicrobial and Nematicidal Activities from the Marine-Derived Fungus Aspergillus sydowii LW09.

Phytopathogens, such as phytopathogenic bacteria, fungi, and nematodes, have caused great losses of crops every year, seriously threatening human health and agricultural production. Moreover, marine-derived fungi are abundant sources of structurally unique and bioactive secondary metabolites that could be potential candidates for anti-phytopathogenic drugs. One new sulfoxide-containing bisabolane sesquiterpenoid aspersydosulfoxide A (1) and nine known analogues (2-10) were isolated from the marine-derived A. sydowii LW09. The absolute configuration of the sulfur stereogenic center in 1 was determined by electronic circular dichroism (ECD) calculations. Compound 5 showed inhibition activity against Pseudomonas syringae, with a minimum inhibitory concentration (MIC) value of 32 μg/mL, whereas, compounds 2, 7, and 8 showed antibacterial activities toward Ralstonia solanacarum, with the same MIC value at 32 μg/mL. Meanwhile, compounds 3, 7, and 8 inhibited the fungal spore germination of Fusarium oxysporum, with the half maximal effective concentration (EC50) values of 54.55, 77.16, and 1.85 μg/mL, respectively, while compounds 2, 3, 7, and 8 inhibited the fungal spore germination of Alternaria alternata, which could be induced by vacuolization of germ tubes, with EC50 values of 34.04, 44.44, 26.02, and 46.15 μg/mL, respectively. In addition, compounds 3, 7, and 8 exhibited nematicidal activities against Meloidogyne incognita second-stage juveniles (J2s). In addition, compound 8 possessed the strongest nematicidal activity of nearly 80% mortality at 60 h with the half lethal concentration (LC50) values of 192.40 μg/mL. Furthermore, compounds 3, 7, and 8 could paralyze the nematodes and then impair their pathogenicity.

Effect of Pochonia chlamydosporia Endophytism and Meloidogyne incognita Parasitism on WRKYs and Defense Gene Expression in Tomato Roots.

The expression of WRKY transcription factors and plant defense-related genes was studied in the roots of Apulian tomato (Solanum lycopersicum) cv Regina di Fasano (accessions MRT and PLZ) endophytically colonized by Pochonia chlamydosporia and parasitized or not by the root-knot nematode (RKN) Meloidogyne incognita. The effect on plant growth, nematode parasitism and histological aspect of the interaction were considered. The association of P. chlamydosporia with RKN-parasitized MRT plants increased the total biomass and shoot fresh weight in comparison with healthy plants and with those only parasitized by RKN, without the endophyte. However, the PLZ accession showed no significant difference in the observed biometric parameters. The number of RKN-induced galls per plant was not affected by endophytism eight days after inoculation. No histological changes were observed in the nematode feeding sites in the presence of the fungus. Gene expression analysis showed an accession-specific response to P. chlamydosporia with differential activation of WRKY-related genes. No significant change was found for WRKY76 expression in nematode-parasitized plants compared with control roots, confirming cultivar susceptibility. Data indicate genotype-specific responses of the WRKY genes to parasitism examined in roots with nematodes and/or endophytic P. chlamydosporia. At 25 days post-inoculation with P. chlamydosporia, no significant difference was observed in the expression of defense-related genes in both accessions, suggesting that salicylic acid (SA) (PAL and PR1) and jasmonate (JA) related genes (Pin II) are not active during endophytism.