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Root-knot nematodes (Meloidogyne spp.) cause extensive damage to tomato and cucurbit crops in protected cultivation systems. An environmentally benign solution for nematode control is the use of plant resistance that mitigates yield losses and reduces the Meloidogyne population in the soil. A collection of three tomato and six cucumber rootstocks was tested for resistance against eight Meloidogyne incognita populations (with different levels of virulence) in comparison with the susceptible variety Moneymaker and the resistant varieties Phantasia or Oskar. In addition, M. enterolobii was included in these experiments to evaluate the response of the tomato and cucumber plant genotypes. Tests were both conducted in a greenhouse or growth chamber and evaluated after completion of one reproduction cycle. The correlation of plant responses to Meloidogyne populations from the different experiments showed significant relationships for 13 and 20 out of 36 combinations for the parameters gall index and number of egg masses per root system, respectively. In particular, two a-virulent reference populations showed significant positive relationships for both parameters, resulting in the same ranking of tested plant genotypes across test systems. Conversely, plant genotypes showed different responses when inoculated with virulent populations of M. incognita or M. enterolobii. Some of the plant genotypes tested showed potential for use in Meloidogyne spp. management strategies. However, cucumber plant genotypes seemed more suitable than tomato genotypes. Furthermore, some of the tested cucumber rootstocks were less sensitive when challenged with M. enterolobii in pot experiments. [ABSTRACT FROM AUTHOR]

Meloidogyne enterolobii, is one of the economically important root-knot species as its ability to develop and reproduce on host plants carrying resistance to other major root-knot nematodes. Recent reports around the world on wide range of plants species including major crops depicts its wide spread. Due to polyphagous nature of M enterolobii and limited control measures, it is important to understand host range to reduce further spread and develop control measures. Meloidogyne incognita and other tropical RKN species are controlled using resistant cultivars carrying Mi gene, but recent reports have shown that virulent isolates of M. incognita are capable to overcome resistance. To determine the host range of 8 M. enterolobii populations and 2 virulent isolates of M. incognita, a study was conducted within the framework of ANR (FR)/DFG (DE) project AEGONE (431627824). 20 crops species previously classified as non-, minor- or major-hosts to M. enterolobii were challenged under greenhouse conditions with 8 M. enterolobii populations (collected from different geographic areas and hosts) and 2 virulent isolates of M. incognita reared as single egg mass lines. Based on the determined reproduction factor (RF), crops were categorized as good-host (RF is ≥1), poor-host (RF between 0 and 1) or non-host (RF=0). Among 20 plant species, 10 showed RF values ≥ 1 for all 8 M. enterolobii populations and 12 showed RF values ≥ 1 for both virulent isolates of M. incognita. Although several reports suggested roses as minor-host to M. enterolobii, no reproduction was observed in all M. enterolobii populations and as well in M. incognita isolates tested. Contrary to recent reports, phacelia and fodder radish were good hosts for 5 and 7 populations of M. enterolobii, respectively. Based on the results it was demonstrated that several populations of M. enterolobii and virulent isolates of M. incognita are capable of reproducing on crops previously reported as non-hosts. Therefore, further studies are underway to investigate the potential to adapt to initially poor hosts, the related costs of fitness and to determine variations on the genome level with differences in host compatibilities. [ABSTRACT FROM AUTHOR]

Meloidogyne enterolobii is a quarantine root-knot nematode posing a major threat to agricultural production systems worldwide. It attacks many host plants, including important agricultural crops, ornamentals, and trees. M. enterolobii is a highly virulent and pathogenic root-knot nematode species, able to reproduce on plants resistant to other Meloidogyne spp. Significant crop damage has been reported in Asia, South America, Africa, the United States, France, and greenhouses in Switzerland. To identify potential inttoduction pathways and ensure appropriate phytosanitary measures and management strategies, accurate detection and identification tools are needed. Therefore, two real-time quantitative polymerase chain reaction (PCR) assays based on the second intergenic spacer region of the ribosomal DNA cistron and the cytochrome oxidase c subunit I (COI) gene using locked nucleic acid probes were developed and validated for fast and reliable detection and identification of M. enterolobii. Analytical specificity was confirmed with 16 M. enterolobii populations, 16 populations of eight closely related Meloidogyne spp., and four species from other nematode genera. Optimizing and testing the assays on two real-time PCR platfonns revealed an analytical sensitivity of one juvenile in a background of 1,(XX) nematodes and the intended limit of detection of one juvenile per 100 ml of soil. Both assays performed equally well, with the COI-based assay showing a slightly better perfomiance concerning detection of M. enterolobii target DNA in complex DNA backgrounds. [ABSTRACT FROM AUTHOR]

The article offers information on the research study done to examine the host range and damage potential of root-knot nematodes in Europe. Topics include need of Polymerase Chain Reaction (PCR) amplification for species identification, enabling of fast and reliable molecular diagnostics producing species-specific amplicons, and rearing of root nematode species is done on tomato in a glasshouse.

In the detection of plant pests, speed and accuracy are vital. High-resolution melting curve (HRMC) analysis was therefore evaluated as a new tool for the identification of root-knot nematodes ( Meloidogyne spp.). On the basis of the second intergenic spacer (IGS2) region of the ribosomal DNA cistron, Meloidogyne chitwoodi, M. fallax and M. hapla were successfully distinguished from each other and the group of the three tropical species, M. incognita, M. arenaria and M. javanica. Conversely, it was shown that the IGS2 region is not suitable for the tropical species M. enterolobii (senior synonym of M. mayaguensis) as the amplification of multiple fragments of different lengths prevented a reliable HRMC analysis. However, the obtained results provide a proof of principle that HRMC analysis can be a suitable single-tube assay for fast and accurate root-knot nematode identification. [ABSTRACT FROM AUTHOR]

The objectives of this study were to determine the efficacy, range of activity and effective concentrations (EC50 and EC80) of abamectin as a seed treatment of tomato against Meloidogyne incognita, M. arenaria and M. javanica. The study revealed that abamectin seed treatment at concentrations ranging between 0.3 and 1 mg a.s. seed-1 is highly effective against the three species of root-knot nematodes, retaining its efficacy in the soil for 8 weeks. The highest EC50 found was reached at 0.2 mg a.s. seed-1. The highest EC80 for the number of egg masses per g root in the three Meloidogyne species was attained at 0.51 mg a.s. seed-1. Abamectin as a seed treatment is promising for the control of root-knot nematodes in the field since only low amounts of active ingredient are required to give adequate protection in the most sensitive stages of tomato root growth and development. [ABSTRACT FROM AUTHOR]

A Correction to this paper has been published: https://doi.org/10.1038/s41597-020-00747-0 [ABSTRACT FROM AUTHOR]

Root-knot nematodes (genus Meloidogyne) are plant parasites causing huge economic loss in the agricultural industry and affecting severely numerous developing countries. Control methods against these plant pests are sparse, the preferred one being the deployment of plant cultivars bearing resistance genes against Meloidogyne species. However, M. enterolobii is not controlled by the resistance genes deployed in the crop plants cultivated in Europe. The recent identification of this species in Europe is thus a major concern. Here, we sequenced the genome of M. enterolobii using short and long-read technologies. The genome assembly spans 240 Mbp with contig N50 size of 143 kbp, enabling high-quality annotations of 59,773 coding genes, 4,068 non-coding genes, and 10,944 transposable elements (spanning 8.7% of the genome). We validated the genome size by flow cytometry and the structure, quality and completeness by bioinformatics metrics. This ensemble of resources will fuel future projects aiming at pinpointing the genome singularities, the origin, diversity, and adaptive potential of this emerging plant pest. Measurement(s) genome • sequence_assembly • sequence feature annotation Technology Type(s) DNA sequencing assay • sequence assembly process • sequence annotation Sample Characteristic - Organism Meloidogyne enterolobii Machine-accessible metadata file describing the reported data: 10.6084/m9.figshare.12410363 [ABSTRACT FROM AUTHOR]

The plant parasitic root-knot nematodes Meloidogyne spp. are a devastating threat to agriculture. The urgent need to search for alternative root-knot nematode control methods that are less environmentally toxic is a demanding challenge to secure the increasing global food demand. Therefore, we combined chemical and biological control strategies to evaluate their management potential on Meloidogyne incognita infested tomatoes. To determine the combined effect of the nematicides Velum and Purpureocillium lilacinum strain 251 formulated as wettable granulate (BioAct WG), we evaluated tomato yield parameters, gall index, soil and root nematode populations. Velum is a chemical nematicide with fluopyram as its active ingredient and BioAct is a biological nematicide based on the egg pathogenic fungus Purpureocillium lilacinum (strain 251). As a single treatment, the nematicide Velum showed better M. incognita reduction at-planting, while BioAct controlled the nematode population throughout the growing season. Greenhouse experiments in two consecutive years, showed that by combining the two nematicides, the M. incognita controlling effect was enhanced and the tomato yield increased compared to single nematicide treatments. The controlling effect of P. lilacinum was lower when M. incognita population increased, presumably based on its limiting ability to parasitize the increasing numbers of nematode eggs. To conclude, we have shown that combining chemical and biological nematicides can successfully control the root-knot nematode M. incognita and increase yields. Velum downregulated the nematode population at-planting and reinforced the biological efficacy of P. lilacinum throughout the growing season. • Root-knot nematodes were controlled by combining chemical and biological nematicides. • Tomato yield increased using the nematicides Velum and P. lilacinum strain 251. • Nematode populations at-planting were crucial for the efficacy of P. lilacinum. [ABSTRACT FROM AUTHOR]