scholarly journals Susceptibility of six tomato cultivars to the root-knot nematode, Meloidogyne incognita

2007 ◽  
Vol 25 (1) ◽  
pp. 73 ◽  
Author(s):  
Sunil K. Singh ◽  
Uma R. Khurma
Keyword(s):  
Meloidogyne Incognita ◽  
Root Knot Nematode ◽  
Inoculum Level ◽  
Root Knot Nematodes ◽  
Egg Masses ◽  
Tomato Cultivars

Six tomato cultivars Moneymaker, Beefsteak, Roma, Summertaste, Mini Roma and Smallfry were tested for their susceptibility to root- knot nematodes at inoculum levels of 200, 400, 600 Juveniles (J2) per pot. All were found to be susceptible to varying degrees as egg masses were present in all with Moneymaker and Roma being the most susceptible and Mini Roma, the least susceptible. The inoculum levels had a significant effect (p<0.05) on the number of galls and plant weights. The gall numbers and plant weights was negatively correlated, with the highest gall numbers and lowest plant weights recorded at the highest inoculum level in all cultivars except in Mini Roma in which there was little variation in gall numbers and plant weights.

scholarly journals Effect of Meloidogyne incognita Inoculum Density and Application Rate of Paecilomyces lilacinus Strain 251 on Biocontrol Efficacy and Colonization of Egg Masses Analyzed by Real-Time Quantitative PCR

2011 ◽  
Vol 101 (1) ◽  
pp. 105-112 ◽  
Author(s):  
S. Kiewnick ◽  
S. Neumann ◽  
R. A. Sikora ◽  
J. E. Frey
Keyword(s):  
Real Time ◽  
Meloidogyne Incognita ◽  
Quantitative Polymerase Chain Reaction ◽  
Application Rate ◽  
Paecilomyces Lilacinus ◽  
Egg Mass ◽  
Root Knot Nematode ◽  
Inoculum Level ◽  
Egg Masses ◽  
Biocontrol Efficacy

The fungal biocontrol agent, Paecilomyces lilacinus strain 251 (PL251), was evaluated for its potential to control the root-knot nematode Meloidogyne incognita on tomato at varying application rates and inoculum densities. Conversely to previous studies, significant dose-response relationships could not be established. However, we demonstrated that a preplanting soil treatment with the lowest dose of commercially formulated PL251 (2 × 105 CFU/g soil) was already sufficient to reduce root galling by 45% and number of egg masses by 69% when averaged over inoculum densities of 100 to 1,600 eggs and infective juveniles per 100 cm3 of soil. To determine the role of colonization of M. incognita egg masses by PL251 for biocontrol efficacy, a real-time quantitative polymerase chain reaction (PCR) assay with a detection limit of 10 CFU/egg mass was used. Real-time PCR revealed a significant relationship between egg mass colonization by PL251 and the dose of product applied to soil but no correlation was found between fungal density and biocontrol efficacy or nematode inoculum level. These results demonstrate that rhizosphere competence is not the key mode of action for PL251 in controlling M. incognita on tomato.

scholarly journals Genome expression dynamics reveals parasitism regulatory landscape of the root-knot nematode Meloidogyne incognita and a promoter motif associated with effector genes

2021 ◽  
Author(s):  
Martine Da Rocha ◽  
Caroline Bournaud ◽  
Julie Dazeniere ◽  
Peter Thorpe ◽  
Clement Pellegrin ◽  
...  
Keyword(s):  
Gene Expression ◽  
Meloidogyne Incognita ◽  
Life Stage ◽  
Regulation Of Gene Expression ◽  
Root Knot Nematode ◽  
Root Knot Nematodes ◽  
Control Of Gene Expression ◽  
Precise Control ◽  
Effector Genes ◽  
Spatio Temporal

Root-knot nematodes are the major contributor to the crop losses caused by nematodes. Root-knot nematodes secrete effectors into the plant, derived from two sets of pharyngeal gland cells, to manipulate host physiology and immunity. Successful completion of the life cycle, involving successive molts from egg to adult, covers morphologically and functionally distinct stages and will require precise control of gene expression, including effectors. The details of how root-knot nematodes regulate transcription remain sparse. Here, we report a life stage-specific transcriptome of Meloidogyne incognita. Combined with an available annotated genome, we explore the spatio-temporal regulation of gene expression. We reveal gene expression clusters and predicted functions that accompany the major developmental transitions. Focusing on effectors, we identify a putative cis-regulatory motif associated with expression in the dorsal glands: providing an insight into effector regulation. We combine the presence of this motif with several other criteria to predict a novel set of putative dorsal gland effectors. Finally, we show this motif, and thereby its utility, is broadly conserved across the Meloidogyne genus and termed it Mel-DOG. Taken together, we provide the first genome-wide analysis of spatio-temporal gene expression in a root-knot nematode, and identify a new set of candidate effector genes that will guide future functional analyses.

scholarly journals Application of Biogas Digestate with Rice Straw Mitigates Nitrate Leaching Potential and Suppresses Root-Knot Nematode (Meloidogyne incognita)

Agronomy ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 227 ◽  
Author(s):  
Yuexi Wang ◽  
Seiya Chikamatsu ◽  
Tuya Gegen ◽  
Kozue Sawada ◽  
Koki Toyota ◽  
...  
Keyword(s):  
Rice Straw ◽  
Nitrate Leaching ◽  
Meloidogyne Incognita ◽  
Application Rate ◽  
Pig Manure ◽  
Test Plant ◽  
Root Knot Nematode ◽  
Root Knot Nematodes ◽  
Leaching Potential ◽  
Biogas Digestate

This study investigated the effects of biogas digestate application to soil with rice straw on nitrate leaching potential and nematicidal activity toward root-knot nematodes Meloidogyne incognita. The following seven treatments were set up: (i) control (CONT); (ii) chemical fertilizer (CF); (iii) wet biogas digestate derived from pig manure (WBD); (iv) and (v) dry biogas digestate derived from a mixture of pig manure and rice straw at an initial C/N ratio of 20 and 30 (DBD20 and DBD30); (vi) and (vii) DBD20 mixed with rice straw to adjust the C/N ratio to 16 (Mix1) and 30 (Mix2), respectively. The application rate of CF and digestates was adjusted to 200 mg N kg−1 soil based on the inorganic ammonium nitrogen contents. Nitrate contents readily increased in all the treatments with incubation, except for Mix2, and those at day 90 were decreased with increasing initial labile C contents. Garden balsam was grown as a test plant for root-knot nematodes using the soils at day 90 and the results showed that the gall index was significantly lower in Mix2 and Mix1 than in CF. These results suggest that dry digestate mixed with rice straw might have potential for lower nitrate leaching and nematicidal properties.

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.

Effect of Southern Root-knot Nematode (Meloidogyne incognita race 3) on Corn Yields in Alabama

2008 ◽  
Vol 9 (1) ◽  
pp. 11 ◽  
Author(s):  
K. L. Bowen ◽  
A. K. Hagan ◽  
H. L. Campbell ◽  
S. Nightengale
Keyword(s):  
Meloidogyne Incognita ◽  
Root Knot Nematode ◽  
Management Decisions ◽  
Root Knot Nematodes ◽  
Percent Loss ◽  
Stage Juvenile ◽  
Risk Thresholds ◽  
Southern Root Knot Nematode ◽  
Soil Losses ◽  
Corn Grain

In Alabama and other southeastern states, corn is frequently planted in rotation with cotton and peanut in order to minimize soil-borne pest problems. Even in areas where peanut is not grown, corn is increasingly being planted in rotation with cotton. However, one root-knot nematode, Meloidogyne incognita race 3, causes damage to both cotton and corn. In this study, we determined levels of corn grain loss when southern root-knot nematodes are present in soil. Losses were 3.8 to 11.4% based on preceding years' counts and 2.2 to 7.0% with current years' counts for every 100 2nd-stage juvenile root-knot nematodes in 100 cm ≥ of soil. Knowledge of the percent loss in corn grain due to southern rootknot nematode populations can provide additional guidance for use of risk thresholds when growers are making management decisions. Accepted for publication 21 June 2008. Published 10 September 2008.

scholarly journals Investigating the in vitro and in vivo nematicidal performance of structurally related macrolides against the root-knot nematode, Meloidogyne incognita

2019 ◽  
Vol 12 (1) ◽  
pp. 24-37
Author(s):  
M.A. Radwan ◽  
A.S.A. Saad ◽  
H.A. Mesbah ◽  
H.S. Ibrahim ◽  
M.S. Khalil
Keyword(s):  
Meloidogyne Incognita ◽  
Root Length ◽  
Egg Mass ◽  
Root Knot Nematode ◽  
Egg Hatching ◽  
Shoot Height ◽  
Egg Masses ◽  
New Family

Summary Avermectins and spinosyns are structurally related natural products of microbial origin and belong to a new family of macrolides which are active against a vast array of invertebrate pests. In the present study, the effects of four members of macrolides; abamectin (ABM), emamectin benzoate (EMB), spinosad (SPI) and spinetoram (SPIT), on Meloidogyne incognita were investigated under in vitro and in vivo conditions. All compounds reduced egg hatching and led to high mortality of the nematode second-stage juveniles (J2). ABM showed the maximum rate of egg hatching inhibition and J2 mortality while SPIT recorded the minimum. All treatments reduced the number of galls, egg masses, eggs/egg mass in roots and J2 in the soil when compared to the control. Based on the 10 folds of the 24 h-LC50 values of J2 mortality in vitro, EMB and ABM exhibited higher percent reduction in galls (79.68 and 71.45%), egg masses (75.19 and 70.54%), eggs/egg mass (60.49 and 40.91%) and J2 in the soil (90.31 and 86.54%), respectively, compared to SPI and SPIT. Significant increase in tomato shoot height occurred in all biopesticides (10 folds) and SPIT (20 folds). SPI at 10 folds of the 24 h-LC50 values of J2 mortality in vitro, significantly increased root length while ABM at 50 folds and SPIT at 20 folds decreased root length by 5.15% and 5.88%, respectively, compared to the untreated inoculated plants. In all treatments, the dry shoot and root weights increased, compared to the untreated control. Our findings suggest that these macrolides have the ability to regulate nematode population densities and may be an alternative to classical nematicides.

scholarly journals Inoculum Level and Inoculation Method Influences on the Pathogenic Activities of Meloidogyne incognita in Studied Model Plant Okra (Abelmoschus esculentus L. Moench)

2021 ◽  
pp. 82-92
Author(s):  
Yadom Y. F. R. Kouakou ◽  
Kouamé Daniel Kra ◽  
Hortense Atta Diallo
Keyword(s):  
Meloidogyne Incognita ◽  
Infected Plant ◽  
Correlation Coefficients ◽  
Root Knot Nematode ◽  
Reproductive Factor ◽  
Inoculum Level ◽  
Root Explants ◽  
Second Stage ◽  
Inoculation Method ◽  
Gall Index

Agricultural activities such as watering crops with nematode-infested water from wells and boreholes, and using infected plant debris as manure or mulch increase root-knot nematode infection. So, this study aims at assessing the influence of the inoculation method and inoculum level of Meloidogyne incognita on the development of root galls on okra plants. Two M. incognita inoculation methods (suspension of individuals and galled root explants) and six inoculum levels (0, 10, 100, 500, 1000 and 2000 second-stage larvae/plant) were studied. The gall index, total numbers and reproductive factor of M. incognita were used to assess the effect of treatments on root gall development. Unlike the reproductive factor, gall index and the total numbers of M. incognita increased with their inoculum level. The pathogenic activities of M. incognita were most significant when crop soils were infested with galled root explants. However, an inverse relationship was found between the inoculum levels of M. incognita and the okra plant’s development. It is reflected by negative correlation coefficients ranging from -0.90 to -0.62. It is therefore important to burn roots infected with root-knot nematodes left in fields so that they do not act as an inoculum for crops.

scholarly journals Heritability of Root-knot Nematode (Meloidogyne spp.) Resistance in Sweetpotatoes

HortScience ◽  
1996 ◽  
Vol 31 (4) ◽  
pp. 622a-622 ◽  
Author(s):  
W. R. Maluf ◽  
S. M. Azevedo ◽  
V.P. Campos
Keyword(s):  
Meloidogyne Incognita ◽  
Meloidogyne Javanica ◽  
Broad Sense Heritability ◽  
Root Knot Nematode ◽  
Egg Masses ◽  
Substrate Removal ◽  
Meloidogyne Spp ◽  
Diverse Origin ◽  
Race 2 ◽  
Resistant Genotypes

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.)

scholarly journals GROWTH AND YIELD RESPONSES OF FIFTEEN CUCUMBER CULTIVARS TO ROOT-KNOT NEMATODE (Meloidogyne incognita)

2019 ◽  
Vol 18 (3) ◽  
pp. 45-52 ◽  
Author(s):  
Tariq Mukhtar ◽  
Muhammad Zameer Kayani
Keyword(s):  
Meloidogyne Incognita ◽  
Growth And Yield ◽  
Root Knot Nematode ◽  
Root Knot Nematodes ◽  
Resistant Cultivars ◽  
Yield Parameters ◽  
Significant Damage ◽  
The World ◽  
Yield Responses ◽  
Moderately Resistant

Root-knot nematodes have become a grave menace to the lucrative production of cucumber throughout the world. These nematodes are mainly controlled by applying nematicides, but their use is often associated with hazards. Alternatively, the use of nematode resistant cultivars is considered to be innocuous and economically feasible. For their fitness as nematode-suppressive crops, the reduction in growth and yield parameters of these cultivars must be assessed. As there is little documented data about the effects of Meloidogyne incognita on the damage of cucumber, therefore, in the present study, the effects of M. incognita were evaluated on growth and yield parameters of fifteen cucumber cultivars. M. incognita significantly negatively affected the growth and yield parameters of all the cucumber cultivars. Shoot and root lengths and shoot weights of all the cultivars were significantly reduced as a result of nematode infection. Maximum reductions in these parameters were recorded in highly susceptible cultivars followed by susceptible ones, while the reductions were minimal in resistant followed by moderately resistant cultivars. On the contrary, the infection by M. incognita resulted in an increase in root weights of all the cultivars. The increase was found to be the maximum in highly susceptible cultivars followed by susceptible and moderately susceptible cultivars. Likewise, the minimum increase was observed in the resistant cultivars followed by moderately resistant cultivars. Similarly, significant variations in yield parameters among fifteen cucumber cultivars were also recorded as a result of M. incognita infection. In the case of highly susceptible cultivars, the reductions in yield parameters were maximum, whereas the reductions in resistant and moderately resistant cultivars were found to be minimum. As cultivars Long Green, Marketmore, Pioneer-II, Dynasty and Summer Green experienced no significant damage compared to susceptible cucumber cultivars and therefore, they are approved for cultivation in nematode infested soils.

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