Number Of Second-stage Juveniles Research Articles

Impact of Cucurbita moschata Resistant Rootstocks on Cucumis sativus Fruit and Meloidogyne incognita Development.

Plant grafting can provide resistance to nematodes. There is a distinct need to determine the role of Meloidogyne incognita-resistant rootstocks on the growth and quality of grafted cucumber plants. Cucumber (Cucumis sativus L.) cultivar Jinchun No. 4 (J) was hole grafted onto the pumpkin (Cucurbita moschata) cultivars Xiuli (X), Banzhen No. 3 (B), and its root to generate JX, JB, and JJ plants. The histopathology and M. incognita development associated with JX, JB, and JJ were analyzed under incubator and high plastic tunnel conditions. Under incubator conditions, M. incognita root galls and egg mass indices associated with the JX and JB resistant rootstocks were significantly (P < 0.05) lower than those associated with JJ susceptible rootstocks. In addition, the number of eggs were 73.3 ± 8.8% and 85.3 ± 7.7% less, respectively. The number of second-stage juveniles (J2s) in JX roots decreased by 57.1 ± 9.2% compared with that in JJ, and the giant cell and J2 development were poor in JX and JB roots. In pot experiments under a high plastic tunnel, plant height, stem diameter, leaf area, and yield of M. incognita-infected JX plants were not significantly different from those of noninoculated control. There was no significant difference in fruit weight, length, firmness, soluble solids, and color among the three grafted plants. The yield per JB plant was increased compared with that of JJ, irrespective of nematode presence. In the M. incognita-infested soil experiment in a high plastic tunnel, the yield per JX and JB plant were significantly higher than JJ (P < 0.05). Thus, the pumpkin rootstock Xiuli and Banzhen No. 3 are promising rootstocks for managing M. incognita without affecting cucumber fruit quality. Grafting provides a good basis for studying the defense mechanism of rootstocks against M. incognita.

Nematicidal Properties of Chitosan Nanoformulation.

Chitosan is the second most abundant bio-polymer available in the world, second only to cellulose. It is found in crustaceous shells, e.g., those of crabs, shrimps, prawns, and fungi, as well as insect exoskeletons. The use of nanoformulations for the management of pests and diseases is receiving increased interest with the advancement of nanotechnology. Here, chitosan nanospheres were obtained from chitosan using the ionic gelation technique. The nanoformulations obtained were characterized using a particle size analyzer, Fourier transform infrared spectroscopy, and a transmission electron microscope. The efficacy of chitosan nanospheres in suppressing the root-knot nematode Meloidogyne incognita was studied. The particle size of nanospheres formulated for this study was 380.2 nm, with a polydispersity index (PI) of 0.4 and Zeta potential of 45.7 or 50.9 mV at pH 5.2. The chitosan nanospheres were spherical and the particles did not agglomerate. FTIR spectra of the chitosan nanospheres peaked at 3334 cm-1, thereby indicating the stretching of the OH and NH group. In In-vitro studies, chitosan nanospheres showed significant nematicidal activity against M. incognita. Under pot culture conditions, chitosan nanospheres (1%- active compound chitosan) at 2ml/plant decreased the nematode population in roots or soil. Compared to the control, the number of galls was reduced by 83.68%, the number of egg masses by 83.85%, the number of adult females by 66.56%, and the number of second-stage juveniles by 73.20%. In a field experiment, application of chitosan nanospheres (1%) was followed by a 18.75% increase in fruit yield compared to the non-treated control.

Identification and Functional Analysis of Tomato MicroRNAs in the Biocontrol Bacterium Pseudomonas putida Induced Plant Resistance to Meloidogyne incognita.

Root-knot nematodes (RKNs, Meloidogyne spp.) seriously damage tomato production worldwide, and biocontrol bacteria can induce tomato immunity to RKNs. Our previous studies have revealed that Pseudomonas putida strain Sneb821 can trigger tomato immunity against M. incognita and that several long noncoding RNAs and microRNAs (miRNAs) are involved in this process. However, the molecular functions of the miRNAs in tomato immune responses remain unclear. In this study, deep small RNA sequencing identified 78 differentially expressed miRNAs in tomato plants inoculated with Sneb821 and M. incognita relative to plants inoculated with M. incognita alone; 38 miRNAs were upregulated, and 40 miRNAs were downregulated. The expression levels of six known miRNAs and five novel miRNAs were validated using RT-qPCR assays. These included Sly-miR482d-3p, Sly-miR156e-5p, Sly-miR319a, novel_miR_116, novel_miR_121, and novel_miR_221, which were downregulated, and Sly-miR390a-3p, Sly-miR394-3p, Sly-miR396a-3p, novel_miR_215, and novel_miR_83, which were upregulated in plants treated with Sneb821 and M. incognita. In addition, Sly-miR482d was functionally characterized through gene silencing and overexpression of its target gene NBS-LRR (Solyc05g009750.1) in tomato and by challenging the plants with M. incognita inoculation. The number of second-stage juveniles (J2) inside roots and induced galls were significantly decreased in both Sly-miR482d-silenced plants and Solyc05g009750.1 overexpressing plants, whereas the activity of superoxide dismutase, peroxidase, and hydrogen peroxide content were significantly increased. The results suggest that Sneb821 could inhibit Sly-miR482d expression and thus regulate tomato immune responses against M. incognita infestation. This study provides novel insights into the biocontrol bacteria-mediated tomato immunity to M. incognita that engages with plant miRNAs.

Evaluation of Effective Microorganisms (EM®) against Root-Knot Nematode (Meloidogyne javanica) in Tomato

Introduction: Plant-parasitic nematodes cause significant yield losses in a wide range of crops (Nicol et al. 2011). Root-knot nematodes (Meloidogyne spp.) are the most important plant-parasitic nematodes, because they widely distributed all around the world and have wide host range (Chapuis-Lardy et al. 2015). Chemical nematicide is one of the primary means of control for plant-parasitic nematodes. Due to negative impact of synthetic nematicides, it will be necessary to develop other management strategies for plant-parasitic nematodes which are safe for the environment and humans (Huang et al., 2016). Latest interest in organic farming lead to substitution for conventional nematicides by low-risk compounds such as natural products derived from plants (Oka et al. 2006). Also, biological control is an interesting option to control these nematodes (Mosahaneh et al. 2020). Effective microorganisms (EM®) consist of a mixture of live cultures of microorganisms such as photosynthetic bacteria, which they are reported to reduce the incidence of pathogenic microorganisms (Condor et al., 2007). Materials and Methods: In the present study, the aerial parts of the marigold (Tagetes erecta) were collected from Shiraz, Iran. Marigold leaves dried in shade and finely grinded using an electric grinder and a stock solution (10% w/v) was prepared. Seeds of tomato (cv. Early-Urbana) were sown in plastic pots containing 1500 g of a sterilized mixture of farm soil (sandy loam soil) and cow manure. The pots were kept under greenhouse conditions with 16:8 h light to dark photoperiod and 27 ± 4 °C. Four-leaf stage seedlings were soil-drenched (50 ml per plant) with EM® or a mixture of equal amount of EM®+ marigold leaf extract at the rate of 5, 10, 15 and 20% and simultaneously inoculated with a suspension of M. javanica (6000 eggs per pot). The experiment was carried out in a completely randomized design with five replications. Sixty days after nematode inoculation, plants were harvested and the vegetative indices including shoots length, shoot fresh and dry weight and root fresh weight and the nematode population indices including the number of eggs as described by Hussey and Barker (1973), number of galls and egg masses per root system as described by Taylor and Sasser (1978) and the number of second stage juveniles (J2s) in the pot were recorded. Finally, the reproduction factor calculated as described by Sasser and Taylor (1978). Data were subjected to one-way analysis of variance (ANOVA) for plant growth parameters and two-way ANOVA for nematode population indices using SAS 9.1 program (Statistical Analysis System Institute Inc., USA). Treatment means were compared using least significance differences (LSD) at p<0.01.Results and Discussion: Results showed that soil drenching of EM® and EM®+ marigold leaf extract increased the plant growth parameters on inoculated and non-inoculated plants as compared to control. The treatment with EM®+ marigold leaf extract at the rate of 20% was the most effective treatment and increased shoot length, shoot fresh weight and shoot dry weight of non-inoculated plants by 33, 39 and 11% respectively, as compared to non-inoculted control plants. In the case of inoculated plants, shoot length, shoot fresh weight, shoot dry weight and root fresh weight of treated plats with EM®+ marigold leaf extract at the rate of 20% were 34, 31, 15 and 11% higher than inoculated control plants. The number of eggs and egg masses per root system and the reproduction factor were significantly reduced in treated plants with EM®+ marigold leaf extract at the rate of 15 and 20%. EM®+ marigold leaf extract at the rate of 20% reduced the number of eggs, galls, egg masses per root system and the reproduction factor by 28, 40, 37 and 27% respectively, as compared to control. The lowest numbers of eggmasses were observed in the root system of tomato plants treated with EM®+ marigold leaf extract at the rate of 20%. It had significant difference than other treatments, except EM® at the rate of 20%. These data for the first time in Iran, suggest that EM® might have utility in controlling root-knot nematodes. A mixture of EM® and marigold leaf extract was more effective than alone application of EM® for control of M. javanica. Findings from this study, suggest that a mixture of equal amount of EM® and marigold leaf extract at the rate of 20% reduced M. javanica reproduction rates in tomato plants grown in greenhouse.

Transcriptomic and Histological Analysis of the Response of Susceptible and Resistant Cucumber to Meloidogyne incognita Infection Revealing Complex Resistance via Multiple Signaling Pathways.

The root-knot nematode (RKN), Meloidogyne incognita, is a devastating pathogen for cucumber (Cucumis sativus L.) specially in production under protected environments or continuous cropping. High level RKN resistance has been identified in African horned melon Cucumis metuliferus (CM). However, the resistance mechanism remains unclear. In this study, the comparative analysis on phenotypic and transcriptomic responses in the susceptible cucumber inbred line Q24 and the resistant CM, after M. incognita infection, was performed. The results showed that, in comparison with Q24, the CM was able to significantly reduce penetration numbers of second stage juveniles (J2), slow its development in the roots resulting in fewer galls and smaller giant cells suggesting the presence of host resistance in CM. Comparative transcriptomes analysis of Q24 and CM before and after M. incognita infection was conducted and differentially expressed genes (DEGs) associated with host resistance were identified in CM. Enrichment analyses revealed most enriched DEGs in Ca2+ signaling, salicylic acid (SA)/jamonate signaling (JA), as well as auxin (IAA) signaling pathways. In particular, in CM, DEGs in the Ca2+ signaling pathway such as those for the calmodulin and calcium-binding proteins were upregulated at the early stage of M. incognita infection; genes for SA/JA synthesis/signal transduction were markedly activated, whereas the IAA signaling pathway genes were inhibited upon infection suggesting the importance of SA/JA signaling pathways in mediating M. incognita resistance in CM. A model was established to explain the different molecular mechanisms on M. incognita susceptibility in cucumber and resistance to M. incognita infection in CM.

First report of Seville root-knot nematode, Meloidogyne hispanica (Nematoda: Meloidogynidae) in the USA and North America.

A high number of second stage juveniles of the root-knot nematode were recovered from soil samples collected from a corn field, located in Pickens County, South Carolina, USA in 2019. Extracted nematodes were examined morphologically and molecularly for species identification which indicated that the specimens of root knot juveniles were Meloidogyne hispanica. The morphological examination and morphometric details from second-stage juveniles were consistent with the original description and redescriptions of this species. The ITS rRNA, D2-D3 expansion segments of 28S rRNA, intergenic COII-16S region, nad5 and COI gene sequences were obtained from the South Carolina population of M. hispanica. Phylogenetic analysis of the intergenic COII-16S region of mtDNA gene sequence alignment using statistical parsimony showed that the South Carolina population clustered with Meloidogyne hispanica from Portugal and Australia. To our best knowledge, this finding represents the first report of Meloidogyne hispanica in the USA and North America.

Effect of Intercropping Onion with Sugar Beet on Productivity of Both Crops and Root-Knot Nematodes Control under Different Onion Plant Densities and Slow-Release N Fertilizer Rates

A field experiment was conducted over two growing seasons 2018/19 and 2019/20, at Ismailia Agric. Exper. and Res. Station, A.R.C., to determine the effect of onion plant densities (2, 3 and 4 rows of onion intercropped with sugar beet) and four nitrogen fertilizer rates (60, 80 and 100 kg N/fad) as blending fertilizer of urea formaldehyde (UF as slow-release N) and traditional urea (TU) compared to control treatment (100 kg N/fad as TU) on productivity, control of root-knot nematodes Meloidogyne spp., land and N use efficiency as well as net return. Results showed that, intercropping two rows of onion with sugar beet significantly increased root, top and sugar yields/fad of sugar beet, TSS% and bulb characters as well as NUE compared to 3 and 4 rows of onion. Meanwhile, increasing onion plant density up to four rows significantly increased plant height and onion yield/fad. Slow-release N fertilizer had a significant effect on sugar beet and onion traits. The blending fertilizer of UF at 100 kg N/fad had the highest sugar beet and onion productivity, while N rate at 80 kg/fad had the highest sugar yield/fad and NUE. Intercropping two rows of onion with application UF+TU at 100 or 80 kg N/fad had the highest values of sugar beet and onion traits, without significant differences in most cases. The applying treatments were studied against root-knot nematodes under field conditions. Generally, the nematode parameters were negatively correlated with intercropping onion with sugar beet compared to check treatment (solid sugar beet). The most effective treatment in reducing the number of galls, egg-masses per root system, root gall index (RGI), egg -masses index (EI) as well as a number of second-stage juveniles (j2) in soil was 4 rows with 80 kg nitrogen in two successive seasons. Intercropping two rows of onion with sugar beet and application blending N fertilizer of UF at 80 kg N/fad had the highest LER value 1.31 and 1.34 and maximizing net return/fad compared to solid sugar beet. Therefore, growing two rows of onion with sugar beet that received 80 kg N/fad as a mixture of UF and TU could be controlled root-knot nematodes, Meloidogyne spp. and increased sugar beet productivity, maximizing land use and grower profitability as well as reduced N fertilizer usage.

Differential Morphological, Structural and Biological Characteristics of Cysts in Heterodera Species in Korea.

Morphological (cyst shape, color, and sizes [length (L), maximum width (W), volume and “a” (L/W)]), structural (vulvar cone slope angle [VCSA], surface wrinkle [VCSW], cyst wall thickness, composition, and texture) and biological characteristics (fecundity, hatching, and emergence [number of second-stage juveniles (J2) from a cyst]) in preceding Heterodera glycines (Hg), currently-recorded H. sojae (Hs) and H. trifolii (Ht) were examined by microscopy. Cysts were lemon-shaped, indicating the genus is Heterodera except for Hs that formed frequently globular cysts with significantly flatter VCSA (102.2°) with smooth VCSW than Hg (50.6°) and Ht (82.0°), but not genus Globodera because of the presence of vulvar cone in Hs. Ht was significantly larger in all morphological characteristics than Hg and Hs, suggesting Ht may be diagnosed differentially by cyst sizes and also host plant preferences. Hs showed smaller “a” value with more globular shape and stronger structures with more thickened and strengthened collagen-like texture of cyst wall than Hg and Ht. This suggests Hs may be diagnosed differently by structural characteristics from the others, especially Hg with similar cyst sizes. There were no significant differences in emergence (inoculum potential) among cyst nematodes due to the offset of fecundity and hatching rate; however, the inoculum potential of Hs may be not so persistent as Hg and Ht in fields because of its lower fecundity and higher hatching rate (causing rapid inoculum loss) than the others. These characteristics of cysts provide information useful for simple and differential diagnoses and reliable management of cyst nematodes.

Nematicidal activity of phytochemicals and their potential use for the control of Meloidogyne javanica infected eggplant in the greenhouse

Nematicidal activities of 17 phytochemicals belonging to the monoterpene, sesquiterpene, phenylpropene and alkaloid classes were assessed in vitro and in pot experiments under greenhouse conditions. The results showed that, based on LC50 values, monoterpenes and phenylpropenes were more toxic than sesquiterpenes and alkaloids to second-stage juveniles (J2) of Meloidogyne javanica. α-Terpinene (LC50 = 36.22 mg/L) displayed the highest toxicity against juveniles, followed by α-pinene (LC50 = 47.49 mg/L), nerolidol (LC50 = 53.60 mg/L) and eugenol (LC50 = 73.45 mg/L). Furthermore, α-pinene, α-terpinene and nerolidol were highly effective in reducing egg hatching of M. javanica after 7 days of treatment displaying IC50 values of 43.28, 49.26 and 50.39 mg/L, respectively. The three compounds showed nematicidal activity against eggs comparable to a reference nematicide, oxamyl. In pot experiment with eggplant, α-pinene, α-terpinene, eugenol and nerolidol induced remarkable reduction in number of galls, egg-masses and eggs per plant, and number of second stage juveniles in soil at concentration of 500 mg/L. Also, these compounds increased the growth parameters of eggplant compared with infected control. α-Terpinene gave nematode control and plant growth similar to oxamyl. The results suggest that these four compounds could be applied for M. javanica management.

Solanum palinacanthum: broad-spectrum resistance to root-knot nematodes (Meloidogyne spp.).

Root-knot nematodes (RKN, Meloidogyne spp.) are harmful phytophagous pests of Solanum spp. Some RKN species are becoming worldwide problems because of their virulence to RKN-resistant Solanum species. A new Solanum species carrying broad-spectrum resistance to Meloidogyne spp. is required for the effective management of this pest. Here we sought to determine the host suitability of RKN to Solanum palinacanthum, a wild Solanum species, and to evaluate its potential effectiveness in RKN management. We identified an RKN-resistant Solanum species, S. palinacanthum, by screening Solanum accessions. We tested its spectrum of resistance to common Meloidogyne spp. in Japan. In pot tests inoculated with second-stage juveniles, S. palinacanthum showed poor host suitability for Melidogyne incognita, M. arenaria genotypes A2-J and A2-O, M. javanica and M. hapla, indicating broad-spectrum resistance to RKN. The development of M. incognita within S. palinacanthum roots was significantly poorer than that in susceptible S. melongena and S. lycopersicum at 10 and 21 days after inoculation. Microplot tests confirmed that the number of second-stage juveniles in plots where S. palinacanthum grew and root galling of the root system were significantly lower than those of susceptible S. melongena, suggesting that the resistance could be used to manage RKN under field conditions. S. palinacanthum showed poor host suitability to all Meloidogyne spp. tested in this study, and it thus has the potential to be used as a genetic resource with broad-spectrum RKN resistance, and it could be effective against multiple RKN species in a field. © 2020 Society of Chemical Industry.

Biofumigation Potentials of Some Brassica Crops to Control Root-knot Nematodes Meloidogyne spp., on Tomato Under Field Conditions

The experiments were conducted to study the efficacy of fodder radish (Raphanus sativus var. Terranovah) and rocket salad (Eruca sativa cv. Baladi) as biofumigation crops for controlling root-knot nematodes Meloidogyne spp., on tomato plants during two successive seasons 2017 and 2018 under field conditions. Three months after cultivation of fodder radish, and rocket salad (the full blooming stage) all parts were incorporated with soil and covered with a transparent polyethylene film. After 4 weeks, the plastic sheets were removed and soil was left for two weeks later, before transplanting tomato seedlings. Results in both seasons, indicated significant reduction (p≤0.05) of nematode parameters on tomato plants. Results revealed that effect of R. sativus var. Terranovah as biofumigation crop as indicated by the percentage reduction in number of galls, egg-masses/root system, and a number of second-stage juvenile (j2) /250 g soil (84, 90, and 84%), and (90,87, and 88%) in seasons 2017 & 2018 respectively. On the other hand, nematicide Vydate (oxamyl) 24% L recorded the percentage reduction in the number of galls, egg-mass/ root system as well as number of second-stage juveniles in soils j2 (90,87, and 87%), and (95,93, and 90%) in season 2017& 2018 respectively. Results revealed that all plant growth criteria on tomato plants increased significantly (p≤0.05) by using the tested treatments. Results indicated that the effect of R. sativus as biofumigation crop recorded the average highest percentages (57, and 92%), and (64, and 102%) in seasons 2017 &2018 respectively. At the same time, nematicide Vydate (oxamyl) 24% L was the most effective in the average highest percentages. i.e., the plant growth vigor, increase, and fruit yield per plant (64, and 98), (73, and 107) in two successive seasons 2017 & 2018 respectively. Gas liquid chromatography-mass spectrometry (GLC-MS) analysis of dichloromethane extract of fodder radish indicated the presence of four glucosinolates, which were identified through their volatile autolysis products. Gluconapin, the major compound was identified by 3- butenyl isothiocynate, while glucoerucin was identified by 4-(methylthio) butyl isothiocynate, which is commonly known as erucin. Sulphoraphane was released from 4-(methylsulfinyl) butyl glucosinolate (glucoraphanin) while 4-(methylsulphony) butyl isothiocyanate commonly known as erysolin was liberated from glucoerysolin. Furthermore, five GLS were also identified in rocket salad. Gluconapin was detected and its presence was identified through its epithionitrile; 4,5-epithiopentanenitrile. The isomers progoitrin and epiprogoitrin were detected by the two hydrolysis products diastereomers threo and erythro 1-cyano-2-hydroxy-3,4-epithiobutane respectively. The aromatic glucosinolate; gluconasturtiin could be identified through its liberated nitrile named as 1-benzenepropane nitrile. Sativin, the major identified compound is 4-mercaptobutyl isothiocyanate.

Variations in the level of resistance to root-knot nematodes (Meloidogyne spp.) infestation among ten cowpeas (Vigna unguiculata L. Walp.) genotypes

The cultivation of cowpea (Vigna unguiculata L. Walp.) cultivars that are tolerant to root-knot nematode attack is among the environmentally safe approach to managing the root-knot nematode menace in cultivated crops. In this study, the tolerance of 10 cowpea genotypes to root-knot nematodes infestation was evaluated in a pot experiment conducted in a Screenhouse, at the University for Development Studies, Nyankpala Campus. The experiment was laid out in a completely randomized design with three replications. The number of second stage juveniles (J2) per 250 cm3 of soil sample were counted while the severity of root-knot nematode damage (root galls) was assessed. The reproduction index (RI) was used to classify the varieties as resistant or susceptible. There was a significant difference (P &lt; 0.05) in the number of second stage juveniles of root-knot nematode (RKN), galling index and RI among the genotypes tested. The study revealed that cowpea genotypes SARI 1-4-90, Padi tuya, Songotra, IT99K-1122, Sanzi and Apagbaala were moderately resistant whereas cowpea genotypes IT86D-610, Zaayura, SARI 5-5-5 and IT07K-299-6 were slightly resistant. Thus, the six moderately resistant cowpea genotypes were suggested to be used as a source of resistance to RKN in future breeding works.

Physicochemical and biological properties of the coffee (Coffea arabica) rhizosphere suppress the root-knot nematode Meloidogyne exigua

ABSTRACTWe investigated the properties of rhizospheric soils infested with root-knot nematode (RKN) Meloidogyne exigua in 17 coffee (Coffea arabica) farms from the Southern region of Minas Gerais, Brazil. Physicochemical (pH, clay and organic matter) and biological properties (RKN parasites and microbiota volatile toxicity on M. exigua) were correlated with the number of second-stage juveniles (J2) and the egg hatching of M. exigua extracted from those rhizospheres. In the five most suppressive farms, the number of J2 was less than 50/100 g of soil and the egg hatching was significantly low. The bacterium Pasteuria penetrans was found in four of the most suppressive farms with an average of 30% of J2 infected with endospores. By using in vitro experiments the microbiota volatiles emitted from the most suppressive soils killed more than 83% of the J2. Additionally, volatiles produced by Fusarium oxysporum, Cladosporium sp. and Syncephalastrum sp. isolated from M. exigua eggs, significantly killed the J2. Identification of nematicidal compounds from the soils by GC-MS supported the strong involvement of the microbiota volatile toward RKN suppressiveness. Clay percentage and pH were similar in farms with the most suppressive soils (42.5% and 6.6%, respectively). Finally, the most suppressive soils came from farms with the highest coffee bean yields. Collectively, these results suggest the strong involvement of parasitic microorganisms, clay percentage and the pH suppressing RKN in soils from the major coffee production region in Brazil, and that volatiles emitted from total microbiota and exclusively from egg-isolated fungi are toxic to M. exigua.

English

The reaction of four wheat RbcS RNAi mutants and wild type to the infection of M. incognita was investigated in a greenhouse pot experiment using plant growth parameters as well as nematode reproduction. Obtained results revealed that all estimated growth parameters of lines under study were reduced by M. incognita infection to various extents. RSS13.2 line showed the highest percentage of reduction of plant total fresh weight, length, and shoot dry weight. It did act as good host for root-knot nematode; therefore, it was classified as susceptible host. In addition, the lowest reduction percentage of fresh and dry weights was observed in RSS8.5 line although it showed high values for nematode development and reproduction parameters; therefore, it seemed to be as a tolerant host. The maximum reduction in chlorophyll content was recorded in RSS7.6 line, whereas, the minimum was obtained from RSS11.5 line. It was evident that none of the five tested wheat lines was immune to M. incognita infection. The lowest numbers of second stage juveniles, galls, and egg-masses were observed in soil and on roots of RSS11.5 line although its plant growth was slightly affected; therefore, it is considered as partially resistant line. It could be concluded from the results of this study that, RNAi mutants of the RbcS were partially effective in suppressing root-knot nematode development. © 2019 Friends Science Publishers

Effect of Bacillus subtilis on Meloidogyne javanica and on Tomato Growth Promotion

Objective: To evaluate under controlled conditions the effect of alternative liquid Bacillus subtilis isolate 34 formulation on Meloidogyne javanica and tomato growth promotion.&#x0D; Statistical Design: The design was completely randomized block with five treatments and eight replicates. The results were submitted to the analysis of variance and the averages compared by the Tukey test with 5% error probability. The statistical package used in the analysis of the data was the program "Sisvar"&#x0D; Location and Duration of the Experiment: The experiment was set up during the period from February 13, 2018 to April 20, 2018 in greenhouse located at the State University of Montes Claros, municipality of Janaúba, MG, Brazil.&#x0D; Methods: Treatments consisted of different times of application of bacteria in tomato seedlings: application of bacteria in the tube at eight and fifteen days after emergence; application of bacteria in the tube at eight and fifteen days after emergence and in pots at 25 and 35 days after transplanting; application of bacteria at 25 and 35 days after transplantation in the pot; Onix® commercial product (Bacillus methylotrophicus-UFPEDA20) and control. After 60 days of transplanting, the number of egg masses, number of galls, number of eggs, number of second-stage juveniles (J2) and reproduction factor, height, fresh and dry shoot mass and fresh root mass of tomato plants were evaluated.&#x0D; Results: There was a reduction in the number of J2, eggs pre root, and eggs per gram of root when the bacteria formulation was applied in the tube + pot and in pot only. The application of the bacteria in the tube + pot and in only pot only presents the highest increase of fresh and dry shoot mass and fresh root mass.&#x0D; Conclusion: The application of the liquid B. subtilis isolated 34 formulation to the soil in the pot and tube + pot reduced the reproduction of M. javanica and promoted greater tomato development.

Mapping quantitative trait loci of Meloidogyne graminicola resistance and tolerance in a recombinant inbred line population of Oryza glaberrima × O. sativa

Summary Host response of BC2F3 recombinant inbred line (RIL) population derived from a cross between African rice (CG14) and Asian rice (IR64) genotypes was evaluated in the field and quantitative trait loci (QTLs) that confer resistance and tolerance to Meloidogyne graminicola were mapped using SSR markers. Of the 155 BC2F3 progenies evaluated, 23 were resistant and six were partially resistant based on the number of second-stage juveniles (J2) per root system and J2 per g roots. Based on yield reduction, 23 progenies were identified as tolerant and 14 were less sensitive to M. graminicola infection. QTLs related to resistance were detected on chromosomes 6, 7 and 12. QTL for tolerance linked to percentage yield reduction was mapped on chromosome 5. QTLs linked to fresh root weight, dry root weight, dry shoot weight, percentage filled grains per panicle and yields were also mapped. QTLs identified will be useful in a breeding programme to develop M. graminicola-resistant and tolerant rice cultivars.

Nitrogen Fertilization and Rhizobacteria in the Control of Meloidogyne javanica in Common Bean Plants

The effects of treating seeds of the common bean with rhizobacteria before sowing associated with different nitrogen (N) doses on the control of the nematode Meloidogyne javanica was evaluated. The assay was carried out in a greenhouse in random blocks, with a factorial arrangement of 5 &amp;times; 5 + 1: five N doses (0, 25, 50, 100, and 200 kg/ha); five isolates: Bacillus pumilus (1, 60 and 76), Bacillus subtilis.-34, Bacillus sp.-36, and one control treatment. The plants were inoculated with 3,000 nematode eggs/pot. After 60 days the assay was evaluated. In the absence of N, B. pumilus-60 promoted a reduction of more than 50% in the number of galls and egg masses compared to the control. B. pumilus (1 and 76) and Bacillus sp.-36 reduced the number of galls in combination with increased N doses. Treatment of seeds with Bacillus in combination with N fertilization contributed to a reduction in the number of galls and nematode egg masses. B. pumilus (60 and 76) reduced the number of galls and egg masses in the absence of N, indicating a nematicidal effect. The treatments had no effect on the number of second-stage juveniles, eggs, or the plant parameters.

Determination of the treatment period of banana seedlings with rhizobacteria in the control of Meloidogyne javanica

Abstract The introduction of rhizobacteria to the soil can be done via treatment of propagating materials. The aim of this work was to evaluate in greenhouse the influence of immersion periods of micropropagated ‘Prata-Anã’ banana seedling roots in suspension of different rhizobacterial isolates on the growth of seedlings and control of Meloidogyne javanica. The experiment was set up in greenhouse in a randomized block design in a 10 x 2 factorial scheme (rhizobacteria isolates) x (immersion periods: 60 and 120 minutes) with 10 replicates. The additional treatment (control) was composed of seedlings without any treatment infected with M. javanica. Treated seedlings were planted in pots containing soil: previously autoclaved sand. After twenty-four hours, suspension containing 3,000 M. javanica eggs was added to the soil. At 60 days, number of galls, egg mass and eggs per root system, number of second-stage juveniles (J2) per 100 cm3 of soil were evaluated and the reproduction factor was calculated. Shoot dry matter mass was also evaluated. Of the four rhizobacteria that reduced the reproductive capacity of the nematode, three were more efficient when seedlings were treated for 120 minutes. The treatment period of banana seedlings did not affect the shoot dry matter yield and all rhizobacteria increased the dry matter weight of seedlings infected with Meloidogyne javanica. It could be concluded that rhizobacteria have different treatment time requirements for seedlings to control the nematode, but do not interfere with the development of seedlings.

Monitoring of Systemic Resistance Induction in Tomato Against Meloidogyne incognita

The potency of three chemical compounds as resistance inducer in tomato plants against root-knot nematode (Meloidogyne incognita) were evaluated using split root system technique. Salicylic acid (SA), Ascorbic acid (AS) and Dipotassium hydrogen phosphate (DKP) was assessed at three concentrations (10, 20 and 50 mM) and the activity of cytoplasmic peroxidase and Phenol oxidase in tomato leaves were measured. Results indicatedthat application of these inducers significantly reduced all nematode related parameters in tomato plants under greenhouse conditions. Salicylic acid (SA) at 50 mM demonstrated the highest reduction in number of second stage juveniles in 250 mg soil, number of galls, egg masses and females/tomato root system compared to inoculated untreated control. These treatments significantly enhanced plant growth parameters of tomato plants i.e., plant height, root length, fresh root, shoot weight and dry shoot weight. Moreover, these resistance inducers enhanced the synthesis and activity of defence enzymes in tomato plants. Phenol oxidase and peroxidase drastically increased in the treated plants compared with un-treated control plants. Application of SA, AS and DKP may provide an environmentally friendly management strategy against root-knot nematode infection in tomato through induction of systemic resistance.

Efficiency of some pesticides of control the disease root knot nematodes caused by Meloidogyne spp. on tomato plants

This study was conducted to evaluate the effectiveness Abamctin, Garland, Resyst three concentrations of 1, 2and 4 ml L-1 in against nematode roots on the tomato. The results showed the effectiveness of each of them in reducing the percentage of the guide patients and the severity of the injury and significant differences for treatment comparison .as achieved treatment before the infection concentration of 4 ml L-1 highest percentage cut to guide patients reaching 1.33 for Abamectin and Alcarlnd compared the treatment of the comparison, which amounted to 4.66. While disease severity amounted to 20% of Abamectin and 26% for Carlnd while the treatment of 95% in comparison. The results showed that all treatments concentration of 4 ml L-1 positively to growth standards for plants tomato of weight mild and dry plants compared with the comparison treatment. Appearance results and there were significant differences for the numbers of adolescent superiority of the treatment before the infection concentration of 4 ml l-1 less number of second stage juveniles. As it recorded 10.33, 50.33, 73.33 young in comparison with the comparison, which reached the highest, number of J2 increased by 106.66.