Deep modifications of the microbiome of rice roots infected by the parasitic nematode Meloidogyne graminicola in highly infested fields in Vietnam

2020 ◽  
Vol 96 (7) ◽  
Author(s):  
Anne-Sophie Masson ◽  
Hai Ho Bich ◽  
Marie Simonin ◽  
Hue Nguyen Thi ◽  
Pierre Czernic ◽  
...  
Keyword(s):  
Parasitic Nematode ◽  
Bacterial Community Composition ◽  
Root Knot Nematode ◽  
Root Tips ◽  
Meloidogyne Graminicola ◽  
Rice Roots ◽  
Functional Capabilities ◽  
Infected Root ◽  
Plant Parasitic ◽  
Root Microbiome

ABSTRACT Meloidogyne graminicola, also known as the rice root-knot nematode, is one of the most damaging plant-parasitic nematode, especially on rice. This obligate soilborne parasite induces the formation of galls that disturb the root morphology and physiology. Its impact on the root microbiome is still not well described. Here, we conducted a survey in Northern Vietnam where we collected infected (with galls) and non-infected root tips from the same plants in three naturally infested fields. Using a metabarcoding approach, we discovered that M. graminicola infection caused modifications of the root bacterial community composition and network structure. Interestingly, we observed in infected roots a higher diversity and species richness (+24% observed ESVs) as well as a denser and more complex co-occurrence network (+44% nodes and +136% links). We identified enriched taxa that include several hubs, which could serve as potential indicators or biocontrol agents of the nematode infection. Moreover, the community of infected roots is more specific suggesting changes in the functional capabilities to survive in the gall environment. We thus describe the signature of the gall microbiome (the ‘gallobiome’) with shifting abundances and enrichments that lead to a strong restructuration of the root microbiome.

scholarly journals Synthesis and transfer of RNAi construct for potential knock-down of gene expression of root-knot nematode (Meloidogyne graminicola) to rice (Oryza sativa L.)

2020 ◽  
Vol 19 (04) ◽  
pp. 36-44
Author(s):  
Phong V. Nguyen
Keyword(s):  
Expression Vector ◽  
Parasitic Nematode ◽  
Oryza Sativa L ◽  
Artificial Microrna ◽  
Root Knot Nematode ◽  
Rnai Construct ◽  
Meloidogyne Graminicola ◽  
Knock Down ◽  
Plant Parasitic

Effectors play key roles in the parasitism of the plant-parasitic nematode. Silencing the effector-coding genes was applied to study the function and role of nematode effectors. In this study, the Mgra16281 gene (ID: MK322955.1) encoding an effector with the unknown function was cloned from the rice root-knot nematode Meloidogyne graminicola isolated in Long An province. To knock-down the expression of this gene, an artificial microRNA was synthesized based on the Osa-MIR528 precursor and inserted into an expression vector. This microRNA can be expressed in rice to investigate the function of MGRA16281 of root-knot nematode via host-induced gene silencing approach (HIGS).

scholarly journals The role of Caenorhabditis elegans sex-determination homologs, Mi-sdc-1 and Mi-tra-1 in Meloidogyne incognita

2021 ◽  
Author(s):  
Anil Baniya ◽  
Soumi Joseph ◽  
Larry Duncan ◽  
William Crow ◽  
Tesfamariam Mengistu
Keyword(s):  
Caenorhabditis Elegans ◽  
Sex Determination ◽  
Meloidogyne Incognita ◽  
Egg Production ◽  
Target Genes ◽  
Parasitic Nematode ◽  
Plant Parasitic Nematode ◽  
Root Knot Nematode ◽  
Model Free ◽  
Plant Parasitic

AbstractSex determination is a key developmental event in all organisms. The pathway that regulates sexual fate has been well characterized at the molecular level in the model free-living nematode Caenorhabditis elegans. This study aims to gain a preliminary understanding of sex-determining pathways in a plant-parasitic nematode Meloidogyne incognita, and the extent to which the roles of the sex determination genes are conserved in a hermaphrodite species, C. elegans, and plant-parasitic nematode species, M. incognita. In this study, we targeted two sex-determining orthologues, sdc-1 and tra-1 from M. incognita using RNA interference (RNAi). RNAi was performed by soaking second-stage juveniles of M. incognita in a solution containing dsRNA of either Mi-tra-1or Mi-sdc-1 or both. To determine the effect of RNAi of the target genes, the juveniles treated with the dsRNA were inoculated onto a susceptible cultivar of cowpea grown in a nutrient pouch at 28 °C for 5 weeks. The development of the nematodes was analyzed at different time points during the growth period and compared to untreated controls. Our results showed that neither Mi-sdc-1 nor Mi-tra-1 have a significant role in regulating sexual fate in M. incognita. However, the silencing of Mi-sdc-1 significantly delayed maturity to adult females but did not affect egg production in mature females. In contrast, the downregulation of Mi-tra-1 transcript resulted in a significant reduction in egg production in both single and combinatorial RNAi-treated nematodes. Our results indicate that M. incognita may have adopted a divergent function for Mi-sdc-1 and Mi-tra-1distinct from Caenorhabditis spp. However, Mi-tra-1 might have an essential role in female fecundity in M. incognita and is a promising dsRNA target for root-knot nematode (RKN) management using host-delivered RNAi.

Comparison of host recognition, invasion, development and reproduction of Meloidogyne graminicola and M. incognita on rice and tomato

Nematology ◽  
2011 ◽  
Vol 13 (5) ◽  
pp. 509-520 ◽  
Author(s):  
Tushar K. Dutta ◽  
Stephen J. Powers ◽  
Brian R. Kerry ◽  
Hari S. Gaur ◽  
Rosane H.C. Curtis
Keyword(s):  
Meloidogyne Incognita ◽  
Host Recognition ◽  
Cortical Region ◽  
Root Knot Nematode ◽  
Root Tips ◽  
Root Knot Nematodes ◽  
Tomato Plants ◽  
Meloidogyne Graminicola ◽  
Second Stage ◽  
Tomato Roots

AbstractThe rice root-knot nematode Meloidogyne graminicola normally infects rice, wheat and several other graminaceous plants. Meloidogyne incognita is a serious pest of dicotyledonous crops, although it can infect and reproduce on some cereals. This paper demonstrates and compares host recognition, development and reproduction of these two species of root-knot nematodes on rice and tomato plants. Attraction bioassays in pluronic gel clearly showed that M. incognita preferred tomato roots to rice or mustard roots, whilst M. graminicola was more attracted towards rice compared with tomato or mustard roots. Based on the attraction data from this study, it can be hypothesised that either: i) the blend of attractants and repellents are different in good and poor hosts; or ii) relatively long-range attractants, together with shorter-range repellents, might affect nematode movement patterns. Some host specific attractants might also be involved. Meloidogyne incognita was able to invade and develop to adult female but did not produce eggs in rice roots. By contrast, M. graminicola developed and reproduced faster on both rice and tomato plants compared with M. incognita. Nevertheless, second-stage juveniles of both these root-knot nematodes showed a similar pattern of distribution inside the roots, preferring to accumulate at the root tips of rice or in the vascular cylinder and cortical region of tomato.

scholarly journals αβ-Dehydrocurvularin isolated from the fungus Aspergillus welwitschiae effectively inhibited the behaviour and development of the root-knot nematode Meloidogyne graminicola in rice roots

2020 ◽  
Author(s):  
Chao xiang ◽  
Ying Liu ◽  
Shi-Ming Liu ◽  
Ya-Fei Huang ◽  
Ling-An Kong ◽  
...  
Keyword(s):  
Active Compound ◽  
Nematicidal Activity ◽  
Field Conditions ◽  
Median Lethal Concentration ◽  
Root Knot Nematode ◽  
Control Efficacy ◽  
Meloidogyne Graminicola ◽  
Rice Roots ◽  
Gall Index

Abstract Background: The root-knot nematode Meloidogyne graminicola has become a serious threat to rice production as a result of the cultivation changes from transplanting to direct seeding. The nematicidal activity of Aspergillus welwitschiae have been investigated in vitro , and the disease control efficacy of the active compound has been evaluated under greenhouse and field conditions. Results: The active compound αβ-dehydrocurvularin (αβ-DC), isolated by nematicidal assay-directed fractionation, showed significant nematicidal activity against M. graminicola , with an median lethal concentration (LC 50 ) value of 122.2 μg mL −1 . αβ-DC effectively decreased the attraction of rice roots to nematodes and the infection of nematodes and also suppressed the development of nematodes under greenhouse conditions. Moreover, αβ-DC efficiently reduced the root gall index under field conditions. Conclusion: To our knowledge, this is the first report to describe the nematicidal activity of αβ-DC against M. graminicola . The results obtained under greenhouse and field conditions provide a basis for developing commercial formulations from αβ-DC to control M. graminicola in the future. Keywords: Meloidogyne graminicola ; αβ-dehydrocurvularin; nematicidal activity; attractiveness; development; behaviour

scholarly journals Construction of artificial microRNA expression vectors for inhibition of Minc16281 gene in root-knot nematode Meloidogyne incognita

2019 ◽  
Vol 18 (4) ◽  
pp. 62-69
Author(s):  
Phong V. Nguyen
Keyword(s):  
Meloidogyne Incognita ◽  
Parasitic Nematode ◽  
Expression Vectors ◽  
Parasitic Nematodes ◽  
Plant Parasitic Nematodes ◽  
Root Knot Nematode ◽  
Gene Encoding ◽  
Soybean Field ◽  
Genes Encoding ◽  
Plant Parasitic

Effectors have been identified to play a very important role in the parasitism of plant-parasitic nematode. To cope with this type of pathogen, many approaches of silencing genes encoding for effectors have been studied and promise to be an effective tool to create plant varieties resistant to plant-parasitic nematodes. In this study, the Minc16281 gene encoding a pioneer effector with unknown function was determined and cloned from a Meloidogyne incognita population isolated from soybean field (ID: MH315945.1). The nucleotide sequence of this gene showed 97% identity to its homolog in GenBank (ID: JK287445.1) used as the control strain in our research. To generate host-induced gene silencing constructs which can potentially silence the expression of Minc16281 gene, two artificial microRNAs were synthesized based on the miR319a structure of Arabidopsis thaliana and inserted into an expression vector in soybean. These microRNAs can be introduced into soybean to investigate the function of Minc16281 on parasitism of root-knot nematode.

scholarly journals αβ-Dehydrocurvularin isolated from the fungus Aspergillus welwitschiae effectively inhibited the behaviour and development of the root-knot nematode Meloidogyne graminicola in rice roots

2019 ◽  
Author(s):  
Chao xiang ◽  
Ying Liu ◽  
Shi-Ming Liu ◽  
Ya-Fei Huang ◽  
Ling-An Kong ◽  
...  
Keyword(s):  
Active Compound ◽  
Nematicidal Activity ◽  
Field Conditions ◽  
Median Lethal Concentration ◽  
Root Knot Nematode ◽  
Control Efficacy ◽  
Meloidogyne Graminicola ◽  
Rice Roots ◽  
Gall Index

Abstract Background: The root-knot nematode Meloidogyne graminicola has become a serious threat to rice production as a result of the cultivation changes from transplanting to direct seeding. The nematicidal metabolites of Aspergillus welwitschiae have been investigated in vitro, and the disease control efficacy of the active compound has been evaluated under greenhouse and field conditions.Results: The active compound αβ-dehydrocurvularin (αβ-DC), isolated by nematicidal assay-directed fractionation, showed significant nematicidal activity against M. graminicola, with an median lethal concentration (LC50) value of 122.2 μg mL−1. αβ-DC effectively decreased the attraction of rice roots to nematodes and the infection of nematodes and also suppressed the development of nematodes under greenhouse conditions. Moreover, αβ-DC efficiently reduced the root gall index under field conditions.Conclusion: To our knowledge, this is the first report to describe the nematicidal activity of αβ-DC against M. graminicola. The results obtained under greenhouse and field conditions provide a basis for developing commercial formulations from αβ-DC to control M. graminicola in the future.

scholarly journals First report about the trapping activity of Stropharia rugosoannulata acanthocytes for Northern Root Knot Nematode

2013 ◽  
Vol 50 (2) ◽  
pp. 127-131 ◽  
Author(s):  
M. Zouhar ◽  
O. Douda ◽  
J. Nováková ◽  
E. Doudová ◽  
J. Mazáková ◽  
...  
Keyword(s):  
Parasitic Nematode ◽  
Fungal Species ◽  
In Vitro Screening ◽  
Meloidogyne Hapla ◽  
Root Knot Nematode ◽  
Arthrobotrys Oligospora ◽  
First Report ◽  
Petri Dishes ◽  
Plant Parasitic

AbstractThis study summarises the results of in vitro screening of the nematophagous activity of Stropharia rugosoannulata and Arthrobotrys oligospora. The tests were conducted with Meloidogyne hapla plant parasitic nematode juveniles placed into Petri dishes containing cultures of the tested fungal species. Immobilisation of the nematodes was observed after 4 and 24 hours. Both species of fungi showed nematophagous activity, however it was much stronger and faster in the case of S. rugosoannulata.

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