Effects of Plant Leaf Extracts on Egg-Masses Hatching and Juveniles Mortality of the Root-Knot Nematode, Meloidogyne Javanica

Heritabilities for resistance to root knot nematodes (Meloidogyne javanica and Meloidogyne incognita races 1, 2, 3, and 4) were studied in a population of 226 sweetpotato clones of diverse origin. For each nematode isolate tested, 128-cell speedling trays were filled with previously inoculated substrate (30000 eggs/1000 mL substrate). Sweetpotato clones suitably tagged and identified were randomly planted in the cells (one plant/cell), with a total of four plants per clone per isolate. Ninety days after inoculation, sweetpotato plants had their roots washed for substrate removal, and treated with 150 mg·L–1 Phloxine B to stain nematode egg masses. The number of egg masses per root was recorded, and plants were accordingly assigned scores from 0 (highly resistant) to 5 (highly susceptible). Broad-sense heritability estimates were 0.87, 0.91, 0.81, 0.95, and 0.93 respectively for resistance to M. javanica and races 1, 2, 3, and 4 of M. incognita. The frequencies of resistant genotypes were higher for M. javanica and lower for M. incognita race 2. Genotypic correlations (rG) among the resistances to the various Meloidogyne isolates utilized were weak, ranging from 0.11 to 0.57, suggesting independent genetic controls. Clones could be selected, however, with high levels of resistance to all nematode isolates tested. (This work was supported by CNPq, CAPES, FAPEMIG, and FAEPE/UFLA.)

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Screening of anti-nematode potential through inhibition of egg hatching in plant-parasitic nematode Meloidogyne javanica

Current Botany ◽

10.25081/cb.2020.v11.6172 ◽

2020 ◽

pp. 93-98

Author(s):

Shilpy Shakya ◽

Bindhya Chal Yadav

Keyword(s):

Management Strategies ◽

Plant Defence ◽

Meloidogyne Javanica ◽

Parasitic Nematodes ◽

Aqueous Extracts ◽

Plant Parasitic Nematodes ◽

Root Knot Nematode ◽

Leaf Extracts ◽

Egg Hatching ◽

Plant Parasitic

Plant-parasitic nematodes have emerged as nature’s most successful among all parasites known till today. These animals have been reported from all terrains of all ecosystems. Their capability to survive on a wide diversity of the host plants, circumvent host plant defence is a few of several of their secrets making them most successful of all known parasites. Among various groups of plant-parasitic nematodes, endo-parasitic nematodes are the most damaging one and also difficult to control. Meloidogyne sps. are commonly known as root-knot nematodes. Our inability to control them is primarily due to our poor understanding of the biology of these plant parasites. Due to the availability of the complete genome sequence of few Meloidogyne species, biotechnological interventions are used to unravel the secrets of their success. Chemical controls of these nematodes are extensively reported in the literature. Due to the environmental toxicity associated with these chemicals, and restrictions on the use of chemicals against nematodes led to screening and development of eco-friendly management strategies. The present study was conducted to screen nematotoxic properties of Neem (Azadirachta indica), Jatropha (Jatropha curcas), Kachnar (Bauhinia variegate), Bel (Aegle marmelos) and Eucalyptus (Eucalyptus globules) leaf extracts against root-knot nematode Meloidogyne javanica in vitro. The aqueous extracts were used against the hatching of the nematode eggs, movement of second stage juveniles (J2) and the viability of the J2 in increasing concentration of the bioactive compound. The eggs were treated with various concentrations of the selected extracts for different time periods ranging from 24h to 6 days. A significant inhibition of egg hatching and increase in the mortality of the nematode juvenile in few of the aqueous extracts were recorded. Reduced egg hatching and increased mortality of the nematode juveniles could be maybe the indicators of the presence of anti-nematode potential in the selected plant leaves. The results from the study can pave the way for the development of eco-friendly management strategies for plant-parasitic nematodes.

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OCCURRENCE OF MELOIDOGYNE JAVANICA PARASITING ROOTS AND NODULES OF PEANUTS IN PARAGUAY

Bragantia ◽

10.1590/s0006-87051997000100009 ◽

1997 ◽

Vol 56 (1) ◽

pp. 87-89

Author(s):

RUBENS RODOLFO ALBUQUERQUE LORDELLO ◽

ANA INES LUCENA LORDELLO ◽

IGNÁCIO JOSÉ DE GODOY

Keyword(s):

Arachis Hypogaea ◽

Central Region ◽

Meloidogyne Javanica ◽

Root Knot Nematode ◽

Tomato Cultivar ◽

Egg Masses ◽

First Report ◽

Arachis Hypogaea L

The root-knot nematode Meloidogyne javanica (Treub, 1885) Chitwood, 1949, was identified in roots, nodules and shells of peanut plants (Arachis hypogaea L.), cv. Florman-INTA, collected from a field in Menno colony, Chaco Central region of Paraguay. Infected plants were observed in patches, showing wilting and drying of vegetative parts. Peanut had been grown ininterruptly for many years in the same area and patches had already been observed in the preceding year in cv. Starr. Nematodes collected from roots in this field reproduced on tomato cultivar rutgers and peanut cultivar florunner and produced egg-masses on roots, nodules and shells of cultivar Florman. This is the first report on M. javanica parasiting peanut in Paraguay.

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Mineral composition of beetroot treated with potential elicitors and inoculated with Meloidogyne javanica

Chemical and Biological Technologies in Agriculture ◽

10.1186/s40538-020-00196-2 ◽

2020 ◽

Vol 7 (1) ◽

Author(s):

Paula Juliana Grotto Débia ◽

Beatriz Cervejeira Bolanho ◽

Claudia Regina Dias-Arieira

Keyword(s):

Population Density ◽

Mineral Composition ◽

Integrated Management ◽

Meloidogyne Javanica ◽

Nematode Population ◽

Root Knot Nematode ◽

Cu Content ◽

Manganese Zinc ◽

Nematode Population Density ◽

Elicitor Treatments

Abstract Background The root-knot nematode Meloidogyne javanica can infect beetroots, causing extensive damage to this food crop. As chemical and genetic control tactics have shown limited efficacy, new strategies are needed to improve the integrated management of this parasite. This study assessed the influence of potential defence elicitors and M. javanica infection on the mineral composition of beetroot. Plants were treated with acibenzolar-S-methyl (ASM), citrus biomass, or a mannanoligosaccharide-based product (MOS) and inoculated with 1000 eggs and second-stage juveniles of M. javanica. At 60 days after inoculation, beetroot plants were harvested and evaluated for nematode population density, vegetative growth, and mineral content. Results All potential elicitors reduced nematode population density in beetroots (p ≤ 0.10) and improved the vegetative parameters of inoculated plants (p ≤ 0.05), except shoot fresh weight. Some minerals were found to be negatively affected by treatments, particularly calcium, whose levels were consistently lower in treated plants. On the other hand, M. javanica inoculation increased magnesium, iron, manganese, zinc, and copper contents in beetroots. However, the latter mineral (Cu content) of inoculated plants was positively influenced by MOS and ASM. Conclusion Potential elicitor treatments did not improve the mineral composition of beetroot, but were effective in reducing nematode population density. Plants inoculated with M. javanica had higher mineral levels. However, gall formation decreases the commercial value of the crop and might render it unsuitable for commercialisation. M. javanica-infected beetroots may be used for nutrient extraction or sold to food processing industries.

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