Root-knot Nematodes In Tomato Research Articles

Effect of Paecilomyces lilacinus on tomato plants and the management of root knot nematodes

Effect of Paecilomyces lilacinus on tomato plant growth and the management of root knot nematodes in tomato was studied. The research work was conducted in Microbiology & Bio-control Laboratory, Department of Plant Pathology, Bangladesh Agricultural University, Mymensingh and in Net-house of Department of Plant Pathology, Bangladesh Agricultural University, Mymensingh, during the period from July, 2016 to October, 2017. In net-house pot culture experiment, four different treatments were used viz., T1: Inoculation of egg masses (10 egg masses/plant) of Nematodes (Meloidogyne spp.), T2: Application of P. lilacinus, T3: Application of egg masses of Nematodes and P. lilacinus simultaneously, and T4: Control (non-treated). Spore suspension (10×105 Conc.) of P. lilacinus was mixed with the soil before transplantation and Meloidogyne spp. was inoculated on three days after transplantation. Application of P. lilacinus in soil enhanced the plant growth parameters of tomato plants. Inoculation of Meloidogyne spp. reduced plant growth and the reduction was increased with the increase of inoculum density of Meloidogyne spp. Maximum plant growth reduction was recorded when Meloidogyne spp. was inoculated alone. The maximum plant growth was recorded in case of application of P. lilacinus to soil. A high percentage (85%) of egg masses of Meloidogyne spp. was infected by P. lilacinus when applied together
 J. Bangladesh Agril. Univ. 17(1): 9–13, March 2019

Resistance induction efficiency of silicon dioxide against Meloidogyne incognita in tomato

The tomato root-knot nematode is one of the main phytosanitary problems in crops. Chemical control is the phytosanitary method most used by farmers, and the study of alternative management of phytonematodes is crucial. The objective of this study was to evaluate the effect of silicon dioxide (SiO2) on the initial development of tomato plants, as well as to determine the best dose of SiO2 for inducing resistance to parasitism by M. incognita. This experiment was set up under a completely randomized design with ten treatments and five replicates in a 5×2 factorial arrangement consisting of five concentrations of SiO2 (0, 0.15, 0.3, 0.45 and 0.6 g dm-³ of soil) with the presence and absence of M. incognita, under greenhouse conditions. The following variables were evaluated: plant height; number of leaves; fresh and dry weight of shoot; percentage of shoot dry matter; root fresh weight; number of galls; final population of nematodes; and population per gram of root. The M. incognita infection affected plant height, number of leaves and shoot fresh weight, while the application of SiO2 negatively affected the formation of galls in the roots of the inoculated plants and the population per gram of root, reducing the final population of nematodes in the root system. SiO2 also provided greater development in the tomato plants, with a significant effect on plant height. The ideal dose was 0.34 g dm-3 of SiO2.

Strigolactones positively regulate defense against root-knot nematodes in tomato.

Strigolactones (SLs) are carotenoid-derived phytohormones that are known to influence various aspects of plant growth and development. As root-derived signals, SLs can enhance symbiosis between plants and arbuscular mycorrhizal fungi (AMF). However, little is known about the roles of SLs in plant defense against soil-borne pathogens. Here, we determined that infection with root-knot nematodes (RKNs; Meloidogyne incognita) induced SL biosynthesis in roots of tomato (Solanum lycopersicum). Silencing of SL biosynthesis genes compromised plant defense against RKNs, whilst application of the SL analog racGR24 enhanced it. Accumulation of endogenous jasmonic acid (JA) and abscisic acid (ABA) in the roots in response to RKN infection was enhanced by silencing of SL biosynthetic genes and was suppressed by application of racGR24. Genetic evidence showed that JA was a positive regulator of defense against RKNs while ABA was a negative regulator. In addition, racGR24 enhanced the defense against nematode in a JA-deficient mutant but not in an ABA-deficient mutant. Silencing of SL biosynthetic genes resulted in up-regulation of MYC2, which negatively regulated defense against RKNs. Our results demonstrate that SLs play a positive role in nematode defense in tomato and that MYC2 negatively regulates this defense, potentially by mediating hormone crosstalk among SLs, ABA and JA.

Synthesis, Nematicidal Activity and Docking Study of Novel Pyrazole-4-Carboxamide Derivatives Against Meloidogyne incognita

Background:A series of novel 2,6-dichloro-4-(trifluoromethyl)phenyl)-3-(difluoromethyl)- 1H-pyrazole-4-carboxamide derivatives were designed and synthesized.Methods:All the title compounds were confirmed by 1H NMR and MS.Results and Conclusion:The primarily nematicidal activity results indicated that some of them exhibited moderate control efficacy against the tomato root-knot nematode disease caused by Meloidogyne incognita.

Effects of inducers of systemic acquired resistance on reproduction of root knot nematodes in tomato

Effects of inducers of systemic acquired resistance on reproduction of root knot nematodes in tomato

Selection of Root-Knot Nematod Resistance in Inbred Tomato Lines Using CAPS Molecular Markers

Tomato root-knot nematode, is one of the most important disease agents in tomatoes (Solanum lycopersicum). A practical and effective method for controlling this disease is by means of tomato genotypes with resistance genes against this disease. Tomato plants are offered resistance to root-knot nematode by Mi gene. Phenotypically observing genetic lines in terrestrial conditions is difficult and time consuming due to concerns about the transfer of this agent to other plants and their stability. By using the molecular markers related to resistance genes, this problem can be avoided and the selection efficiency can be increased. In this project, 34 inbred lines were tested using 1 CAPS marker associated with Mi gene, resistant and susceptible genotypes were identified. In the study, 34 genotypes were not found to be homozygous resistant (MI / MI) genotypes whereas 7 genotypes were found to be heterozygous resistant (MI / mi) and 27 genotypes (mi / mi)homozygous susceptible. As a result of this study, root-knot nematode is the basis for developing resistant varieties.

The Role of Sugar Transporter Genes during Early Infection by Root-Knot Nematodes.

Although pathogens such as nematodes are known to hijack nutrients from host plants, the mechanisms whereby nematodes obtain sugars from plants remain largely unknown. To determine the effects of nematode infection on host plant sugar allocation, soluble sugar (fructose, glucose, sucrose) content was investigated using high-performance liquid chromatography with refractive index detection and was found to increase significantly in tomato (Solanum lycopersicum, Sl) leaves and roots during early infection by root-knot nematodes (RKNs). To further analyze whether sugar transporters played a role in this process, the expression levels of sucrose transporter (SUT/SUC), Sugars Will Eventually be Exported Transporter (SWEET), tonoplast monosaccharide transporter (TMT), and vacuolar glucose transporter (VGT) gene family members were examined by qRT-PCR analysis after RKN infection. The results showed that three SlSUTs, 17 SlSWEETs, three SlTMTs, and SlVGT1 were upregulated in the leaves, whereas three SlSUTs, 17 SlSWEETs, two SlTMTs, and SlVGT1 were induced in the roots. To determine the function of the sugar transporters in the RKN infection process, we examined post-infection responses in the Atsuc2 mutant and pAtSUC2-GUS lines. β-glucuronidase expression was strongly induced at the infection sites, and RKN development was significantly arrested in the Atsuc2 mutant. Taken together, our analyses provide useful information for understanding the sugar transporter responses during early infection by RKNs in tomato.

The use of toluidine blue staining combined with paraffin sectioning and the optimization of freeze-thaw counting methods for analysing root-knot nematodes in tomato

Root-knot nematodes (RKNs) (Meloidogyne spp.) are one of the most damaging crop pests and cause severe yield losses worldwide. Easier and more efficient methods are needed for assessing nematode infestations and host plant resistance. In the present study, we combined toluidine blue staining and paraffin sectioning to observe the establishment of giant cells (GCs; redifferentiated cells induced by nematode feeding) and the developmental status of RKNs in tomato (Solanum lycopersicum). The number of RKNs was counted using a modified freeze-thaw counting method. Finally, three tomato lines with different levels of RKN resistance, but otherwise identical genetic backgrounds, were tested to verify the applicability of the combined method. The results suggested that using toluidine blue staining combined with paraffin sectioning and freeze-thaw counting accurately reflects the level of RKN resistance of tomato plants.

Synthesis and nematocidal activity of novel 1-(3-chloropyridin-2-yl)-3-(trifluoromethyl)-1H-pyrazole-4-carboxamide derivatives

A series of novel fluorinated pyrazole carboxamides derivatives were designed and synthesized. All these title compounds were confirmed by NMR, MS and elemental analysis. The primary nematicidal activity results indicated that some of them (compound 5b, 5e, 5r and 5s) exhibited 100% efficacy against the tomato root-knot nematode disease caused by Meloidogyne incognita. The docking results indicated that compound 5r interacts with amino acid residue Tyr 121 of AchE via hydrogen bond and Phe288 of AchE via CH–π interaction, respectively.

Synthesis, nematocidal activity and docking study of novel chiral 1-(3-chloropyridin-2-yl)-3-(trifluoromethyl)-1H-pyrazole-4-carboxamide derivatives

A series of novel chiral fluorinated pyrazole carboxamides derivatives were designed and synthesized. All these title compounds were confirmed by NMR and MS. The primarily nematocidal activity results indicated that some of them exhibited good control efficacy against the tomato root-knot nematode disease caused by Meloidogyne incognita. The docking results indicated that compound 5n interact with amino acid residue Tyr 121, Trp 279 of AchE via hydrogen bond.

Evaluation of bacterial biological control agents for control of root-knot nematode disease on tomato

Among 19 bacterial strains isolated in Yunnan from rhizosphere soils and plant tissues, Bacillus methylotrophicus strain R2-2 and Lysobacter antibioticus strain 13-6 exhibited the highest antagonistic activity against the tomato root-knot nematode Meloidogyne incognita in plate and greenhouse pot experiments. The two strains, when applied as soil drenches or seed treatments in greenhouse experiments, reduced root-knot severity and incidence on tomato compared to no-bacteria controls. In tomato field trials conducted in separate years, soil drench treatment with either strain reduced root-knot disease levels and increased yields compared to the control. Levels of disease control and yield enhancement provided by the strains were higher than those using the chemicals abamectin and carbofuran. This is the first report of B. methylotrophicus being used as a biocontrol agent against a plant parasitic nematode and the first demonstration that B. methylotrophicus and L. antibioticus can suppress disease caused by root-knot nematodes in the field.

Application of PSX biocontrol preparation confers root-knot nematode management and increased fruit quality in tomato under field conditions

ABSTRACTPSX is a combination of biocontrol bacteria that can potentially prevent and control soil-borne diseases for a variety of crop cultivars. In this study, we investigated the utility of PSX in controlling root-knot nematodes in tomato under field conditions. The application of PSX reduced the severity of disease caused from Meloidogyne incognita by 63–69% and increased tomato yield by 31.5–39%. Furthermore, to investigate the effect of PSX treatment on tomato fruit quality, we quantified the soluble sugar, titratable acid, soluble solids, and vitamin C contents in fruit postharvest. We demonstrated that PSX treatment improved tomato fruit quality. Finally, we also showed that the total nitrogen (N), available N, potassium, and organic matter contents in the soil increased after PSX treatment. PSX is a promising biocontrol preparation that can provide beneficial effects to tomato growers, including biological control of root-knot disease, plant growth promotion, enhanced tomato fruit quality, and increased levels of organic fertilisers in the soil.

Domateste kök-ur nematodlarına dayanıklılık genleri

Root-knot nematodes (Meloidogyne spp.) are the most important pests of tomato. They cause galls on the roots of susceptible tomato plants. These galls prevent adequate water and nutrient uptake resulting in stunted growth, leaf yellowing, wilting and death during heavy infection. It is required that controlling of them for successful tomato growing. One of the best management tools in controlling root-knot nematodes is using resistant varieties. Mi-1 gene in tomato has been successfully used against Meloidogyne species including M. incognita, M. javanica and M. arenaria for a long time. Besides Mi-1 gene, different genes which confer resistance to Meloidogyne spp. in tomato have been reported. The review has proposed to present information about resistance genes to root-knot nematodes in tomato.

Associated bacteria of different life stages of Meloidogyne incognita using pyrosequencing-based analysis.

The root knot nematode (RKN), Meloidogyne incognita, belongs to the most damaging plant pathogens worldwide, and is able to infect almost all cultivated plants, like tomato. Recent research supports the hypothesis that bacteria often associated with plant-parasitic nematodes, function as nematode parasites, symbionts, or commensal organisms etc. In this study, we explored the bacterial consortia associated with M. incognita at different developmental stages, including egg mass, adult female and second-stage juvenile using the pyrosequencing approach. The results showed that Proteobacteria, with a proportion of 71-84%, is the most abundant phylum associated with M. incognita in infected tomato roots, followed by Actinobacteria, Bacteroidetes, Firmicutes etc. Egg mass, female and second-stage juvenile of M. incognita harbored a core microbiome with minor difference in communities and diversities. Several bacteria genera identified in M. incognita are recognized cellulosic microorganisms, pathogenic bacteria, nitrogen-fixing bacteria and antagonists to M. incognita. Some genera previously identified in other plant-parasitic nematodes were also found in tomato RKNs. The potential biological control microorganisms, including the known bacterial pathogens and nematode antagonists, such as Actinomycetes and Pseudomonas, showed the largest diversity and proportion in egg mass, and dramatically decreased in second-stage juvenile and female of M. incognita. This is the first comprehensive report of bacterial flora associated with the RKN identified by pyrosequencing-based analysis. The results provide valuable information for understanding nematode-microbiota interactions and may be helpful in the development of novel nematode-control strategies.

Evaluation of Some Botanicals and Trichoderma harzianum for the Management of Tomato Root-knot Nematode (Meloidogyne incognita (Kofoid and White) Chit Wood)

Root-knot nematode disease caused by Meloidogyne incognita (Kofoid and White) Chit wood) is one of the major constraints for successful cultivation of tomato (Lycopersicon esculentum Mill.) in Ethiopia. Hence, the present study was conducted to evaluate the effect of leaf and seed extracts of four botanicals viz., Rape seed (Brassica napus L.), Lantana (Lantana camara L.), African marigold (Tagetes erecta L.) and Neem (Azadirachta indica L.) at 5% and 10% concentrations and T. harzianum at 5% plus control were tested on root-knot nematode under in vitro and also to evaluate their against root-knot nematode development and their role on plant growth parameters of tomato under in vivo condition. Plant extracts were more effective and significantly inhibited egg hatching and immobilizing the J2 larval mortality of M. incognita than T. harzianum. Aqueous extract of all the tested plants inhibited egg hatching of nematode and resulted 84.67-100% mortality of the J2 juveniles of M. incognita in vitro at the 10% concentration after 72 h of exposure time. There were no significant differences among the treatments of rape seed leaf (84.7%) at 10% concentration and Lantana camara (87%), African marigold (86.3%) and Neem leaf (85%) at 5% concentration after 72 h. Aqueous seed extracts of A. indica more significantly inhibited egg hatching and larva mortality of the J2 of M. incognita in vitro at the 10% concentration and immobilized by 89, 93 and 100% after 24, 48 and 72 h of exposures, respectively, while at similar concentration of T. erecta, B. napus and L. camara leaf extracts exhibited 92, 89 and 93.2% inhibition of egg hatching and 75, 62.1 and 73% larval mortality, respectively. The effect of different botanicals and T. harzianum singly and in combination were studied for the management of tomato root-knot nematode under greenhouse condition. There was a significant difference in the reduction of root-knot nematode incidence, root-knot nematode population, nematode reproduction rate (NRR), number of galls and egg masses per plant were recorded. In pot culture condition, the application of leaf extract of individual plant in the presence of the nematode significantly enhanced the growth of tomato seedlings in comparison to the control. A significant increase in plant height, shoot weight and root weight of the seedlings were observed at the 10% concentration of leaf extracts in comparison to control. There was a significant difference in the reduction of root-knot nematode population, nematode reduction rate, number of galls and egg masses per plant of L. camara combined with T. harzianum. The mean fruit weight and total yield were observed highest in the combination treatment of L. camara combined with T. harzianum. This study results revealed that the test plants are readily available to farmers at no cost and able to reduce nematode population below economic threshold.

Expression of tomato salicylic acid (SA)‐responsive pathogenesis‐related genes in Mi‐1‐mediated and SA‐induced resistance to root‐knot nematodes

The expression pattern of pathogenesis-related genes PR-1, PR-2 and PR-5, considered as markers for salicylic acid (SA)-dependent systemic acquired resistance (SAR), was examined in the roots and shoots of tomato plants pre-treated with SA and subsequently infected with root-knot nematodes (RKNs) (Meloidogyne incognita). PR-1 was up-regulated in both roots and shoots of SA-treated plants, whereas the expression of PR-5 was enhanced only in roots. The over-expression of PR-1 in the whole plant occurred as soon as 1 day after SA treatment. Up-regulation of the PR-1 gene was considered to be the main marker of SAR elicitation. One day after treatment, plants were inoculated with active juveniles (J2s) of M. incognita. The number of J2s that entered the roots and started to develop was significantly lower in SA-treated than in untreated plants at 5 and 15 days after inoculation. The expression pattern of PR-1, PR-2 and PR-5 was also examined in the roots and shoots of susceptible and Mi-1-carrying resistant tomato plants infected by RKNs. Nematode infection produced a down-regulation of PR genes in both roots and shoots of SA-treated and untreated plants, and in roots of Mi-carrying resistant plants. Moreover, in resistant infected plants, PR gene expression, in particular PR-1 gene expression, was highly induced in shoots. Thus, nematode infection was demonstrated to elicit SAR in shoots of resistant plants. The data presented in this study show that the repression of host defence SA signalling is associated with the successful development of RKNs, and that SA exogenously added as a soil drench is able to trigger a SAR-like response to RKNs in tomato.

Evaluation of Antagonistic Plant Materials to Control Southern Root Knot Nematode in Tomato

Marigold ((Tagetes patula), crotalaria (Crotalaria juncia), rapeseed plant (Brassica rapa) and oat (Avena sativa) as antagonistic plant and tomato (Lycopersicon esculentum), CL1104 variety as control, were evaluated to determine the effect on southern root knot nematode population in pot experiment at Tsukuba, Japan in year 2010. Completely Randomized Design (CRD) with three replications was used. Initial juvenile population was 30.0±2.8 per 20g soil. The juvenile nematode population was counted 63 days after transplanting and biomass of plants was incorporated in soil. Population was again counted 11 days and 13 day after biomass incorporation. At final count of Juvenile nematode population, it was found highest in tomato (66.6 /20g soil). Highest control was achieved in marigold (2.3 juvenile/20g soil) followed by crotalaria (3.0 juvenile/20g soil. Marigold and crotalaria followed by oat in rotation with tomato were observed as best antagonist plants to control Southern root knot nematode.

Biocontrol of Meloidogyne incognita inciting disease in tomato by using a mixed compost inoculated with Paenibacillus ehimensis RS820

Meloidogyne spp. causes root-knot disease in tomato plants. Biological control of the disease may present economically feasible, agronomically durable and environmentally safe alternative of nematicides. A chitinolytic bacterial strain, Paenibacillus ehimensis RS820, previously isolated from the soil in Korea, produced lytic enzymes in higher amounts and inhibited the growth of phytopathogenic root-knot nematodes. Moreover, the juveniles and eggs of root-knot nematodes induced secretion of lytic enzymes by RS820 including chitinases, gelatinases and collagenases. Furthermore, mixed compost containing increased amounts of chitin and inoculated with RS820 was prepared in the present study. Use of the mixed compost not only reduced the disease caused by root-knot nematodes but also improved the plant growth. The extent of inoculation of the mixed compost with RS820 significantly influenced its ability to control the root-knot disease in tomato. The mixed compost also significantly altered the activity and density of the rhizosphere bacteria. Chitinase and gelatinase producing soil bacteria, as well as their enzyme activities, were significantly influenced by the mixed compost. The mixed compost proposed in the present study may represent a viable alternative to nematicides against the root-knot nematodes in tomato.

Comparison of PCR-based molecular markers for identification of Mi gene

Tomato (Solanum lycopersicum) is an important horticultural plant in intensive agriculture. Many pests and pathogens affect tomato worldwide. Root-knot nematodes (RKNs) are considered to be one of the most important pathogen groups. Development of resistant tomato varieties to nematode provides an economically and environmentally approach for the management of nematodes. The Mi-1 gene confers resistance to RKNs in tomato. Since resistance testing to RKN is time consuming, laborious, and costly, molecular markers linked to the resistance gene have been developed for breeding purposes. Mi-1 gene is located on short arm of chromosome 6 and very tightly linked to Ty-1 gene. The genomic region containing Mi-1 and Ty-1 is genetically very short. Therefore, there is problem introgressions of plants bearing both Mi-1 and Ty-1. Therefore, some markers such as Rex used for screening of Mi-1 gene can give false-positive results in plants with some of the begomovirus-resistant germplasm derived from Ih902, which has begomovirus-resistance genes introgressed from Solanum habrochaites. Although molecular markers tightly linked to Mi-1 gene have been developed, they have not been applied to a wide range of plants carrying Ty-1 gene or not carrying Ty-1, and compared with each other. In the present study, these markers have been employed in tomato lines and hybrids carrying Ty-1 gene or not carrying Ty-1, and evaluated with each other. A total of 116 tomato plants were tested by markers JB-1, Rex, PMi12, and Mi23. The JB-1 yielded accurate results in all the genotypes tested. Markers Rex, PMi12, and Mi23 gave consistent results in plants that do not have Ty-1 gene. PMi12 and Mi23 also produced logical findings for plants carrying Ty-1. However, marker Rex-1 produced false-positive results in other samples bearing Ty-1 gene, except four plants. Our findings showed that both PMi12 and Mi23 markers can be suggested for screening of RKN resistance in tomato-breeding programs.

Mapping of a Heat-Stable Gene for Resistance to Southern Root-Knot Nematode in Solanum lycopersicum

Root-knot nematodes (Meloidogyne spp.) can cause severe problems in tomato production in warm climates. To date, Mi-1 is the only gene that has been used widely to develop cultivars for controlling disease caused by nematodes around the world. However, Mi-1 does not provide resistance to the pest when the soil temperature is above 28 °C. Tomato breeding line ZN17 has been reported to possess resistance to Meloidogyne incognita at high temperatures (32 °C). To identify markers linked tightly to resistance, an F2 population was developed by crossing the resistance line ZN17 to susceptible line 09C84. Analysis of F2 individuals by inoculating M. incognita suggested that resistance in ZN17 is conditioned by a single dominant gene temporarily designated as Mi-HT. Linkage analysis suggested that Mi-HT is located on the short arm of chromosome 6. One marker, W737, co-segregated with Mi-HT. Comparisons of map positions of Mi-HT, Mi-1, and Mi-9, as well as marker genotypes in LA2157, Motelle, and ZN17 suggested that Mi-HT might be a homologue of Mi-1 and Mi-9 or a new gene. The results obtained in this study will facilitate fine-mapping and cloning of the gene as well as marker-assisted breeding for heat-stable resistance to southern root-knot nematodes in tomato.