Influence of organic additives on the incidence of root-knot nematode,Meloidogyne javanica in roots of tomato plants

Glasshouse experiment was conducted to assess the impact of green chopped leaves of four test plants (Lantana camara, Ficus virens, Kigelia pinnata and Ficus bengalensis) and two nematicides (Phorate and Carbofuran) on the plant growth parameters of tomato cv. K25 and on the root-knot development. Results revealed that all the tested treatments significantly (p = 0.05) improved plant growth parameters and reduced root-knot development compared to control. Among the tested organic additives, chopped green leaves of Lantana camara added to soil gave the highest enhancement in plant growth parameters, including plant height, fresh and dry weight, number of fruits and fruit weight with the values of 94.2 cm, 106.8 g, 31.6 g, 7.2 and 153.3 g respectively, as well as a greater reduction of Meloidogyne javanica reproduction and development but exhibiting a lower response compared to nematicides. There was also significant reduction in root-knot development in tomato plants growing in other organic additive amended soil.     

Screening of tomato cultivars in the presence of the root-knot nematode,Meloidogyne javanica

In the present study, 12 varieties of tomato, viz., Arka Vikas, Damayanti, F-hybrid, Hybrid Padmarag, Hybrid Tripti, Marudam, Punjab chhoara, Pusa early dwarf, Punjab kesari, P.K.M.I, Roma and Pusa Ruby were screened for the presence of the root-knot nematode, M. javanica to obtain information on the varying degrees of resistances to tomato cultivars. All the cultivars of tomato tested were found to be infected with the root-knot nematode, M. javanica, however, to a varying extent. Consequently, there was a reduction in the growth parameters of cultivars leading to have an impact on the yield and quality of fruits. The cultivar, Marudam was found resistant while the cultivar the Pusa early dwarf was moderately resistant and rest of the 10 cultivars was highly susceptible.     

Long-range physical maps of two loci (Aps-1 and GP79) flanking the root-knot nematode resistance gene (Mi) near the centromere of tomato chromosome 6

The root knot nematode resistance gene Mi in tomato has been mapped in the pericentromeric region of chromosome 6. With the objective of isolating Mi through a map-based cloning approach, we have previously identified and ordered into a high-resolution genetic linkage map a variety of tightly linked molecular markers. Using pulsed-field gelelectrophoresis and various rarely cutting restriction enzymes in single, double and partial digestions, we now report long-range physical maps of the two closest flanking markers, acid phosphatase-1 (Aps-1) and GP79, which span over 400 and 800 kb, respectively. It is concluded that the physical distance between both markers is larger than predicted on the basis of genetic linkage analysis. Furthermore, two RFLP markers (H3F8 and H4H10) which map genetically to the same locus as Aps-1 do not show physical linkage, indicating severe suppression of recombination in this region of the chromosome. Finally, no evidence was obtained showing the presence of a CpG island near Aps-1.     

Effect of vesicular-arbuscular mycorrhiza on survival,penetration and development of root-knot nematode in tomato

Summary Effect of mycorrhizal colonisation byGlomus fasciculatum on survival, penetration and development of the root knot nematodeMeloidogyne incognita in tomato was studied. The number of giant cells formed in mycorrhizal plants was significantly low. Mycorrhizal roots did not prevent the penetration by nematode larvae. Root extract from the mycorrhizal plants brought about 50% mortality of the nematode larvae in four days time.     

丛枝菌根真菌对不同番茄品种抗根结线虫病的影响

【背景】根结线虫病害严重制约我国设施蔬菜的生产。丛枝菌根真菌(Arbuscular Mycorrhizal Fungi,AMF)作为土壤中最重要的有益真菌之一,可以促进植物生长,提高植物抗病性,减轻土传真菌和线虫病害的发生。在蔬菜保护地栽培中,AMF对于植物线虫病防治作用的研究受到了广泛关注。【目的】针对番茄生产中危害最严重的南方根结线虫(Meliodogyne incognita)病害问题,研究AMF和番茄品种不同组合的抗线虫效应,以期为菌根真菌作为生物防治剂和生物菌肥应用于实际生产提供技术基础。【方法】在灭菌土壤中,人工接种根结线虫,比较不同菌种Rhizophagus intraradices(Ri)、Acaulosporamellea(Am)及菌种组合Rhizophagusintraradices+Acaulosporamellea(Ri+Am)在不同番茄品种(感病品种蒙特卡罗和抗线虫品种仙客1号)上对南方根结线虫侵染和繁殖的影响,研究AMF对根结线虫的拮抗效应。另外,采用南方根结线虫连作发病的土壤,在感病品种蒙特卡洛上接种AMF混合菌种Ri+Am,番茄苗移栽入连作土壤中,测定各生长指标和调查根结和卵块数量,评价接种AMF处理对根结线虫病的防治效果。【结果】在灭菌土壤中,普通番茄品种蒙特卡罗的菌根效应显著优于抗线虫番茄品种仙客1号,表现为前者单位根重的根结和卵块的数量均比对照显著降低,而后者仅降低了卵块数量;蒙特卡罗上接种Ri+Am混合菌种的效果优于接种单一菌种Am和Ri;而仙客1号上接种Ri的效果更好。接种线虫也显著影响了AMF的侵染,而且对抗性品种仙客1号的影响更为明显。但除了接种Am的处理,大多数处理收获时菌根侵染率仍维持较高的水平(70%以上)。在连作土壤中,感病品种蒙特卡罗接种混合菌种Ri+Am具有较好的抗/耐线虫效应,主要表现为促进植株生长,显著降低根结和卵块数量,但菌根侵染率较灭菌土壤低,约为40%。【结论】综合以上结果,表明菌根化苗能够在一定程度上减轻根结线虫病的危害。土壤灭菌条件下,在感病和抗线虫番茄品种上接种AMF能够减轻线虫的侵染和繁殖,而且在感病品种上的防治效果更加显著。在连作土壤中,在番茄感病品种上接种AMF也表现较好的抗线虫效果。     

Evaluation of pomegranate (Punica granatum L. var. Gabsi) peel extract for control of root-knot nematode Meloidogyne javanica on tomato

The present study was carried out to assess the nematicidal potential of Punica granatum L. against the root-knot nematode Meloidogyne javanica responsible for yield losses in tomato. Varied concentrations of methanolic, ethanolic and aqueous extracts from pomegranate peels were investigated for activity against eggs and juveniles of M. javanica in in vitro assays. All extracts used significantly inhibited egg hatch by over than 75%, but viability of second-stage juveniles (J2) was not significantly inhibited by ethanolic extract. Aqueous extract was assessed at the concentration of 10, 25 and 50% against M. javanica on tomato in greenhouse trials; pomegranate peels powder was also tested at the rate of 3, 6 and 9 g as a soil amendment. Both extracts significantly reduced nematode infestations; aqueous extract enhanced plant growth but powder amendment exhibited a phytotoxicity compared to the untreated plants. The reduction in number of galls, egg masses and nematode reproduction rate was recorded.     

Ralstonia solanacearum colonization of tomato roots infected by Meloidogyne incognita

Bacterial wilt, caused by Ralstonia solanacearum, is one of the most serious diseases of tomato (Solanum lycopersicum). Concomitant infection of R. solanacearum and root‐knot nematode Meloidogyne incognita increases the severity of bacterial wilt in tomato, but the role of this nematode in disease complexes involving bacterial pathogens is not completely elucidated. Although root wounding by root‐knot nematode infection seems to play an important role, it might not entirely explain the increased susceptibility of plants to R. solanacearum. In the present study, green fluorescent protein (GFP)‐labelled R. solanacearum distribution was observed in the root systems of the tomato cultivar Momotaro preinoculated with root‐knot nematode or mock‐inoculated with tap water. Fluorescence microscopy revealed that GFP‐labelled R. solanacearum mainly colonized root‐knot nematode galls, and little or no green fluorescence was observed in nematode‐uninfected roots. These results suggest that the gall induced by the nematode is a suitable location for the growth of R. solanacearum. Thus, it is crucial to control both R. solanacearum and root‐knot nematode in tomato production fields to reduce bacterial wilt disease incidence and effects.     

Effect of Nodularia harveyana biomass on the incidence of root-knot nematode (Meloidogyne incognita) in tomato

An acetone extract of Nodularia harveyana wasshown to be toxic to the free-living nematode Cephaloboides oxycerca. This antagonistic effect wastested in pot culture trials with lyophilized biomasson gall induction by the root-knot nematode Meloidogyne incognita, using different methods ofapplication of the cyanobacterial biomass to thetomato plants. The trials revealed a possibleutilization of biomass of this cyanobacterium as aprotection agent against this phytoparasite.     

Rice root-knot nematode (Meloidogyne graminicola) infestation in rice

Rice (Oryza sativa) is an important staple food crop for majority of human population in the world in general and in Asia in particular. However, among various pests and diseases which constitute important constraints in the successful crop production, plant parasitic nematodes play an important role and account for yield losses to the extent of 90%. The major nematode pests associated with rice are Ditylenchus angustus, Aphelenchoides besseyi, Hirschmanniella spp., Heterodera oryzicola and Meloidogyne graminicola. However, rice root-knot nematode (M. graminicola) happens to be the most important pest and is prevalent in major rice producing countries of the world. In India, the distribution of M. graminicola in rice growing areas of different states has been documented in nematode distribution atlas prepared by All India Coordinated Research Project (Nematodes) and published by Directorate of Information and Publications of Agriculture, Indian Council of Agricultural Research, New Delhi, India during 2010. M. graminicola affected rice plants show stunting and chlorosis due to the characteristic terminal swellings/galls on the roots which ultimately result in severe reduction in growth and yield. Number of eco-friendly management technologies against M. graminicola have been developed and demonstrated, including the use of bioagents for minimising the losses due to rice root-knot nematode. This review is focused on collating information to understand the current scenario of rice root-knot nematodes with greater emphasis on its ecological requirements, damage symptoms, biology, morphology, host range and management strategies.     

拮抗菌生物有机肥对番茄根结线虫的防治作用

通过室内离体试验和温室盆钵试验,评价3株能够水解胶原蛋白的细菌XZ-173(解淀粉芽孢杆菌)、SL-25(吉氏芽孢杆菌)和KS-62(多粘类芽孢杆菌)对番茄根结线虫的防治能力.结果表明:XZ-173、SL-25、KS-62菌悬液对二龄幼虫(J2)的24 h致死率分别达到75.9%、66.7%和50.0%,处理7 d根结线虫虫卵孵化率分别为17.8%、28.9%和37.6%,而对照无菌水二龄幼虫死亡率和虫卵孵化率分别为17.4%和53.6%.在根结线虫发病土壤中施用以3种拮抗菌等比例混合发酵的生物有机肥,防治效果较好,与对照相比,根际土壤中根结线虫数减少84.0%,并且番茄植株根上的根结数和虫卵数显著减少,促进了作物地下部根系和地上部植株的生长.说明拮抗菌生物有机肥对防治根结线虫病害具有广阔的应用前景.     

Biocontrol of root-knot nematode Meloidogyne incognita by the isolates of Bacillus on tomato

Fifteen isolates of Bacillus, isolated from the root-knot nematode suppressive soils, were used for the biocontrol of Meloidogyne incognita on tomato. Bacillus isolates B1, B4, B5 and B11 caused greater inhibitory effect on hatching of M. incognita than caused by other isolates. In addition, these isolates (B1, B4, B5 and B11) caused greater colonisation of tomato roots and also caused greater increase in the growth of tomato seedling than caused by other isolates. All the isolates of Bacillus were able to increase growth of tomato and caused reduction in galling and nematode multiplication in green house tests. Isolates B1, B4, B5 and B11 caused a greater increase in growth of tomato and higher reduction in galling and nematode multiplication than other isolates in a green house test. These isolates were also tested for hydrogen cyanide (HCN) and indole acetic acid productions. Only one isolate (B13) produced HCN out of 15 tested. On the other hand, isolates B5, B11, B4 and B1 showed greater production of IAA than the other 11 isolates tested. This study suggests that Bacillus isolates B5, B11, B4 and B1 may be used for the biocontrol of M. incognita on tomato.     

Biocontrol of root-knot nematode Meloidogyne incognita by the isolates of Pseudomonas on tomato

Biocontrol of root-knot nematode Meloidogyne incognita was studied on tomato using 15 isolates of fluorescent Pseudomonads isolated from pathogen suppressive soils. Pseudomonas aeruginosa (isolates Pa8, Pa9 and Pa3) caused greater inhibitory effect on hatching of M. incognita than other isolates. In addition, isolates Pa8, Pa9 and Pa3 caused greater colonisation of tomato roots and also caused a greater increase in the growth of tomato seedlings. These isolates also caused a greater increase in growth of tomato and higher reduction in galling and nematode multiplication in a green house test than is caused by other isolates. Isolates Pf1, Pf5, Pf6 and Pa13 were unable to increase growth of tomato and caused less reduction in galling and nematode multiplication compared to other isolates. Only 10 isolates produced siderophores on chromo-azurol sulfonate (CAS) agar medium and isolate Pa12 showed greater production of siderophore followed by Pa11, Pa9, Pf10, Pa3 and Pf5. Similarly, isolates Pa14, Pa12, Pf10, Pa9, Pa8, Pa7 and Pa6 produced greater amount of HCN than the other isolates tested. Isolates Pa8 and Pa9 showed greater production of IAA than the other 13 isolates tested. This study suggests that P. aeruginosa isolates Pa8 and Pa9 may be used for the biocontrol of M. incognita on tomato.     

Damage functions and thermal requirements of Meloidogyne javanica and Meloidogyne incognita on watermelon

The relationship between the initial (P_i) and final (P_f) population densities of Meloidogyne javanica and yield of watermelon, Citrullus lanatus, cv. Sugar Baby were determined in pot and field experiments. In the pots, the maximum reproduction rate of the nematode was 14, and the equilibrium density was 49 400 eggs/100 cm³ of soil. Yield data represented as fresh top weight fitted the Seinhorst damage function (P < 0.001, R² = 0.7), and the minimum relative yield (m) was 0.65 at P_i ≥ 3200 eggs/100 cm³ of soil and the tolerance limit (T) 74 eggs/100 cm³. In the field experiments (2011 and 2012), the maximum reproduction rate was 73 and 70, and the equilibrium density 32 and 35 second‐stage juveniles (J2)/100 cm³ soil. Yield data represented as fruit weight fitted the Seinhorst damage function in 2011 (P < 0.001, R² = 0.92) and the m‐ and T‐values were 0.63 and 20 J2/100 cm³ of soil, respectively. Meloidogyne incognita and M. javanica needed similar length of time for development to egg‐laying females and life cycle completion at 24.4°C.     

Biological control of root-knot nematode,Meloidogyne incognita infesting tomato

Talc based formulations of two antagonistic fungi, Acremonium strictum W. Gams and Aspergillus terreus Thom were tested separately and together for their ability to suppress the development of root-knot disease of tomato caused by the root-knot nematode, Meloidogyne incognita Kofoid & White in two consecutive trials (2007–08). Tomato seedlings were each inoculated with M. incognita at 2 infective second stage juveniles /g of soil. M. incognita caused up to 48% reduction in plant growth parameters compared to un-inoculated control. Control efficacy achieved by combined soil application of both fungi, in terms of galls/root system and soil population/50 ml of soil, was 66 and 69% respectively at 60 days of inoculation compared to control. Soil application by individual fungus did not achieve as much effectiveness as the biocontrol agents applied together. The combined treatment was found to have antagonistic effect on M. incognita development and increased plant vigor. Incorporation of fine powder of chickpea pod waste with talc powder was beneficial in providing additional nutrients to both plant and biocontrol agents and increased the activity of the nematophagous fungi in soil. A. strictum and A. terreus were successfully established in the rhizosphere of tomato plants up to the termination of the experiment.     

Field assessment of efficacy of nitrogen salts to control the root-knot nematode (Meloidogyne javanica) on tomato

Influence of different nitrogen salts at electrical conductivity levels (EC2, 4 and 8?mmhos/cm) on tomato and root-knot nematode (Meloidogyne javanica) and their interactions was evaluated under field conditions. It was found that both diammonium phosphate ((NH₄)₂HPO₄) and ammonium sulphate ((NH₄)₂SO₄) were more effective than ammonium chloride (NH₄Cl) in causing an obvious suppression of M. javanica infection on tomato through reducing root galling and nematode reproduction and improving tomato growth and yield and their suppressive effect was similar to that of oxamyl or ethoprophos. At higher ECs, the tested nitrogen salts did not greatly affect pH, EC and salinity of rhizospheric soil except NH₄Cl at EC8 that caused higher EC and salinity over the untreated control which makes NH₄Cl less suitable candidate. Therefore, the use of (NH₄)₂HPO₄ and (NH₄)₂SO₄ alone or in combination with other control measures could control M. javanica and improve the growth and yield of tomato under field conditions.     

Nematicidal effect of an Amaranthus hypochondriacus L. cystatin (AhCPI) on the root-knot nematode Meloidogyne incognita (Kofoid and White) Chitwood

The root-knot nematode Meloidogyne incognita is one of the most damaging plant parasitic nematodes in the world. In this study, the effect of cystatin from Amaranthus hypochondriacus (AhCPI) as a potential control agent for M. incognita was explored. In vitro bioassays demonstrated that AhCPI affects the growth and development of eggs and the infectivity of juveniles (J2) of M. incognita, such as mortality and slower development, showing characteristic tissue damage. Mortality levels were quantified by Probit analysis, estimating LC₅₀s of 1.4 mg/mL for eggs and 0.028 mg/mL for J2. In planta bioassays showed that infected tomato seedlings treated with 0.056 mg/mL of AhCPI showed a 60% reduction in the number of galls, as compared with untreated J2-inoculated seedlings. Under greenhouse conditions, three applications of 10 mL of AhCPI (1.4 mg/mL) in the soil around the stem of M. incognita-infected tomato plants, reduced the number of galls by 93 ± 8%, as compared to the control M. incognita-infected plants. The application of AhCPI to the infected plants increased the yield (10.7%) of harvested tomato fruits, as compared to infected plants. These results show the potential of AhCPI for the control of M. incognita in tomato plants.     

Interaction of a root-knot nematode (Meloidogyne hapla) and plant intraspecific diversity in clover-grass communities

Aims Soil organisms can influence the plant diversity-productivity relationship at species level; however, little is known about their role in the relationship at an intraspecific level. This study aimed to investigate the interaction between the effects of plant intraspecific diversity and a root-knot nematode on primary production and community evenness.     

Effects of chicken manure and summer ploughing on root-knot nematode (Meloidogyne javanica) management in cantaloupe (Cucumis melo var. cantalupensis)

Abstract

A 2-year trial was performed in two regions of Ardestan (Iran, Isfahan province) to investigate effects of chicken manure and summer ploughing on root-knot nematode (Meloidogyne javanica) in two infested cantaloupe fields. Before planting cantaloupe, summer ploughing and chicken manure (3, 6 and 9?T/ha) separately and combination of these treatments were applied in nematode-infested fields. At the harvest time, the number of galls, egg masses, gall and egg mass indices and multiplication rate were determined. Also, quantitative and qualitative parameters of cantaloupes in different treatments were evaluated. The results revealed that double summer ploughing in combination with 6?T/ha chicken manure treatments had the best effects on the control of M. javanica. By applying this treatment, reduction of the egg mass number, gall number, total population in root and soil and reproduction factor were observed 17, 6.75, 8591?g/root and 3.37?g/root, respectively (compared to control: 132.5, 36.87, 45037?g/root and 23.13, respectively). It also had positive effect on fruit weigh (28 vs. 18.25?kg) and root dry weight (3.8 vs. 2.08?g). According to the results, it seems that decrease in growth parameters and yield reduction due to root-knot nematode could be overcome by incorporation of summer ploughing and applying the chicken manure with the most efficacy in increasing the quantity and quality of the yield.     

Differential expression of root-knot nematode resistance genes in tomato and pepper: evidence with Meloidogyne incognita virulent and avirulent near-isogenic lineages

Reproduction of artificially selected near isogenic Meloidogyne incognita lineages virulent and avirulent against the Mi resistance gene of tomato was assessed on host and resistant lines and cultivars of pepper. Egg mass production following inoculation of individual potted seedlings with second-stage juveniles was studied in experiments conducted in controlled environment. Artificially selected Mi-virulent nematode populations were unable to develop on resistant pepper lines PM 217 and PM 687. This suggests that the genetic systems governing resistance to root-knot nematodes are differently expressed in tomato and pepper, in spite of the very close phylogenetic relationships and structural genomic homologies occurring between these two vegetable crops. Moreover, these artificially selected nematode populations were also found unable to develop on the susceptible pepper cultivars California Wonder and Doux Long des Landes, while their pathogenicity was not significantly affected on susceptible tomatoes. Due to the existence of naturally virulent Meloidogyne populations, these results enhance the need for a better understanding of the mechanisms involved, in order to develop new forms of management of plant resistance to root-knot nematodes.