Elicitation of Differential Responses in the Root-Knot Nematode Meloidogyne incognita to Tomato Root Exudate Cytokinin, Flavonoids, and Alkaloids

2018 ◽  
Vol 66 (43) ◽  
pp. 11291-11300 ◽  
Author(s):  
Hillary K. Kirwa ◽  
Lucy K. Murungi ◽  
John J. Beck ◽  
Baldwyn Torto
Plant Disease ◽  
2019 ◽  
Vol 103 (7) ◽  
pp. 1551-1558 ◽  
Author(s):  
Xia Li ◽  
Hai-Jing Hu ◽  
Jing-Yu Li ◽  
Cong Wang ◽  
Shuang-Lin Chen ◽  
...  

Root-knot nematodes (Meloidogyne spp.) cause serious crop losses worldwide. The colonization of tomato roots by endophytic bacteria Bacillus cereus BCM2 can greatly reduce Meloidogyne incognita damage, and tomato roots carrying BCM2 were repellent to M. incognita second-stage juveniles (J2). Here, the effects of BCM2 colonization on the composition of tomato root exudates was evaluated and potential mechanisms for BCM2-mediated M. incognita control explored using a linked twin-pot assay and GC-MS. On water agar plates, J2 preferentially avoided filter paper treated with tomato root exudates (organic phase only) from plants inoculated with BCM2, visiting these 67.1% less than controls. In a linked twin-pot assay, BCM2 treatment resulted in a 42.0% reduction in the number of nematodes in the soil, a 43.3% reduction in the number of galls and a 47.7% decrease in the density of M. incognita in root tissues. Analysis of root exudate composition revealed that BCM2 inoculation increased the number of components in exudates. Among these, 2,4-di-tert-butylphenol, 3,3-dimethyloctane, and n-tridecane secretions markedly increased. In repellency trials on water agar plates, J2 avoided 2,4-di-tert-butylphenol, n-tridecane, and 3,3-dimethyloctane at concentrations of 4 mmol/liter. In a linked twin-pot assay, inoculation with 2,4-di-tert-butylphenol or 3,3-dimethyloctane reduced the number of nematodes in the soil (by 54.9 and 70.6%, respectively), the number of galls (by 53.7 and 52.4%), and the number of M. incognita in root tissues (by 67.5 and 36.3%). BCM2 colonization in tomato roots affected the composition of root exudates, increasing the secretion of substances that appear to be repellent, thus decreasing M. incognita J2 infection of roots.


Nematology ◽  
2007 ◽  
Vol 9 (6) ◽  
pp. 771-776 ◽  
Author(s):  
Richard Sikora ◽  
Abd El-Fattah Dababat

AbstractThe non-pathogenic endophytic Fusarium oxysporum strain 162 (FO162) has been selected for its capacity to reduce root-knot nematode galling on tomato. The objectives of this study were to investigate the influence of this fungus on invasion of tomato roots by Meloidogyne incognita. The number of M. incognita that invaded roots of plants treated with FO162 was significantly lower (reductions of 36.0-55.9%) than in the non-treated controls in linked twin-pot chambers. The results demonstrated that colonisation of the roots by FO162 affects the number of M. incognita that penetrate the roots. The results of a choice test in the absence of a plant indicated that the tomato root exudates collected from plants colonised by FO162 are either less attractive or they exude substances that have repellent activity toward M. incognita juveniles.


Author(s):  
A. Manivannan ◽  
K. K. Kumar ◽  
S. Varanavasiappan ◽  
S. Manimegalai ◽  
K. Poornima ◽  
...  

Nematology ◽  
2000 ◽  
Vol 2 (8) ◽  
pp. 871-879 ◽  
Author(s):  
Samia Massoud ◽  
Susan L.F. Meyer ◽  
Daniel Roberts ◽  
David Chitwood

AbstractThe bacterium Burkholderia cepacia (strain Bc-2) and the fungus Trichoderma virens (strain Gl-3) were investigated for activity against the nematode Meloidogyne incognita. Culture filtrates from Bc-2 and Gl-3 contained extracellular factors that inhibited egg hatch and second-stage juvenile (J2) mobility. Size fractionation results and lack of detectable chitinase or protease activities from Bc-2 and Gl-3 culture filtrates suggested that the inhibitory factors in the in vitro assays were non-enzymic. Tomato root explant cultures of M. incognita treated with T.virens culture filtrate had 42% fewer eggs and J2 per g of roots than cultures treated with control medium that had not been inoculated with T. virens. In glasshouse tests with tomato, Bc-2 and Gl-3 were applied individually as seed coatings and as root drenches in both viable and non-viable formulations. At the 65-day harvest, non-viable B. cepacia was the only treatment that suppressed eggs and J2 per g of roots (29% suppression) compared to water controls. Evaluation de l'activité antagoniste de Trichoderma virens et Burkholderia cepacia envers le nématode Meloidogyne incognita - La bactérie Burkholderia cepacia (souche Bc-2) et le champignon Trichoderma virens (souche G1-3) ont été étudiés dans l'optique de leur action envers le nématode Meloidogyne incognita. Les filtrats de culture de Bc-2 et de G1-3 contiennent des facteurs extracellulaires inhibant l'éclosion et la motilité des juvéniles de deuxième stade (J2) du nématode. Les résultats de fractionnements relatifs à la taille et la nondétection d'une activité chitinasique ou protéasique dans les filtrats de culture de Bc-2 et G1-3 suggèrent que les facteurs inhibant présents lors des expériences in vitro ne sont pas de nature enzymatique. Des élevages de M. incognita sur explants de racines de tomate traités avec des filtrats de culture de T. virens produisent des oeufs et des J2 en nombre inférieur de 42% à celui d'élevages traités par un milieu témoin, non inoculé avec T. virens. Lors d'essais en serre sur tomate, Bc-2 et G1-3 ont été appliqués séparément, soit en pralinage des semences, soit sur la tranchée, et en formulation vivante ou non-vivante. A la récolte, après 65 jours, la formulation non-vivante de B. cepacia s'est révélée le seul traitement diminuant le nombre d'oeufs et de J2 par g de racines: moins 29% par rapport au témoin ne contenant que de l'eau.


2015 ◽  
Vol 7 (1) ◽  
pp. 124-130
Author(s):  
M. Muthulakshmi ◽  
B. Anita ◽  
S. Subramanian

The indigenous egg parasitic fungal isolates, Engyodontium aranearum was evaluated for its nematicidal potential against root knot nematode, Meloidogyne incognita. The study revealed 53.75 per cent egg parasitization by the fungal isolate. Fungal colonies grew over the eggs and fungal hyphae penetrated the egg shells resulting in rupturing of egg shell layers, enzymatic digestion and empty eggs. The fungal culture filtrate was found to inhibit egg hatching by 83.42 per cent and caused upto 91.36 per cent juvenile mortality. This isolate also reduced the attraction of infective juveniles towards tomato root by 79.29 per cent. It seems to be a first report on the antinemic property of the fungus E. aranearum against root knot nematode, M. incognita and its effect was found comparable with Paecilomyces lilacinus which is known as an efficient nematode egg parasitic fungus.


2009 ◽  
Vol 25 (2) ◽  
pp. 189-192 ◽  
Author(s):  
Kamal A.M. Abo-Elyousr ◽  
Magd El-Morsi Awad ◽  
M.A. Abdel Gaid

Nematology ◽  
2005 ◽  
Vol 7 (1) ◽  
pp. 125-132 ◽  
Author(s):  
Rong De Jin ◽  
Joo Won Suh ◽  
Ro Dong Park ◽  
Yong Woong Kim ◽  
Hari B. Krishnan ◽  
...  

Abstract Plant-parasitic nematodes are distributed worldwide and affect a broad range of important agronomic plant species. Chitinolytic bacteria were evaluated as potential biological control agents of the root-knot nematode, Meloidogyne incognita, on tomato. After transplantation of seedlings into pots containing soil amended with chitin compost, chitin broth, or respective controls, soil was inoculated with nematode eggs and infective second-stage juveniles (J2). Samples taken at 4, 6 and 8 weeks after inoculation indicated that fresh weights of plants did not vary between treatments or between treatments and controls. The gall index was lower in the plants grown in the chitin-amended soil at each time point. Activities of soil chitinase and β-1,3-glucanase were greater in those soils amended with chitin compost and chitin broth. Gall index of tomato root was negatively correlated with soil chitinase activity. Activities of tomato root chitinase and β-1,3-glucanase were higher in plants growing in non-chitin-amended soil at 6 and 8 weeks after nematode infestation. Chitinase activity in tomato root was positively correlated with the gall index of tomato root. The results indicate the potential of chitinase producing bacteria to alleviate nematode parasitism in important vegetable crops.


2018 ◽  
Vol 16 (1) ◽  
pp. 29-35 ◽  
Author(s):  
Long Cheng ◽  
Wen Zhao ◽  
Zhong-Hua Shen ◽  
Tian-Ming Xu ◽  
Hong-Ke Wu ◽  
...  

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.


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