Endophytic Bacteria from Solanum nigrum with Plant Growth-Promoting and Fusarium Wilt-Suppressive Abilities in Tomato

Fifteen endophytic bacterial isolates from Solanum nigrum and S. nigrum var. villosum stems were screened for their plant growth-promoting potential and antifungal activity against Fusarium oxysporum f. sp. lycopersici (FOL). Isolates SV65, SV68 and SV109 were the most efficient in controlling the development of the disease (77-92%) and in improving tomato growth (32-62%) compared to the controls. They were characterized and identified by using 16S rDNA sequencing genes as being Bacillus amyloliquefaciens subsp. plantarum for the strain SV65 (KR818073) and B. methylotrophicus for the two strains SV68 (KR818074) and SV109 (KR818076). Gas Chromatography-Mass Spectrometry analysis of the n-butanol extract from B. amyloliquefaciens subsp. plantarum SV65 matched phthalic acid, mono(2-ethylhexyl)ester as major compound. The bacterium B. amyloliquefaciens subsp. plantarum SV65 and B. methylotrophicus SV109 were shown to be chitinase-, protease-, pectinase-, phosphatase-, and indole 3-acetic acid (IAA)-producing agents. Furthermore, B. methylotrophicus SV68 produced chitinase, pectinase, and IAA (28.49 µg/ml), and B. amyloliquefaciens subsp. plantarum SV65 excreted siderophores andoxalic and malic acids. This study demonstrates that S. nigrum and S. nigrum var. villosum can be potential plant species for isolation of endophytic bacteria serving as biocontrol and biofertilizing agents for the improvement of production of tomato grown in FOL infested and noninfested soils

Effects Of Organic Substrates Nature On The Composting Process Parameters AndCompost Extract Efficiency On Soil-Borne Plant Diseases

Four Composting windrows were carried out by the wastes (about 8 000 kg) in pyramidal form (height 1.5 m with base of 8m x 2 m) which constitute four different treatments: 1st treatment : 100% Cattle manure, 2nd treatment : 80% Cattle manure + 20% Sheep manure, 3rd treatment : 70% Cattle manure + 20% Sheep manure + 10% Poultry manure and 4th treatment : 50% Cattle manure + 20% Sheep manure + 20% Poultry manure+ 10% crushed wheat straw. Windrows were watered every time is necessary and turned over after 15 days. Temperature rased every two days and samples rased in every turned over. The physicochemical parameters of composting process revealed that the highest temperature of windrows was in thermophilic phase and has reached 66°C for T4 rich in carbon than for other treatments. The basic pH in the beginning decrease for all treatments and approachs the neutrality at the end of composting process, essentially for T1. A decrease of nitrogen percentage during composting probably due to a low level of C/N ratio in the beginning.The second part of this study starts in the maturity stage, a compost extract were prepared from different composts one volume of compost in 5 volume of water and 5 days of extraction period. The four obtained compost extracts, were experimented on different plants pathogens (Rhizoctonia solani, Fusarium solani, Fusarium oxysporum, Fusarium roseum, Fusarium graninearum and Phytophtora erythroseptica) in vivo and in vitro

Synthesis of new antifungal 1,2,4-bis-oxadiazolines using cycloaddition reaction of nitrile oxide with bis-Schiff base

922-928A series of arylaldehydes and acetophenone when treated with 1,2-ethanediamine afford the bis-Schiff bases <span style="mso-ansi-language: DE" lang="DE">N,N’-bis(arylidene)-ethane-1,2-diamines 1-8, N,N’-bis(arylmethylene)-ethane-1,2-diamines 9-10 and the N,N’-bis(1-phenylethylidene)-ethane-1,2-diamine 11. The bis-imines 1-11<span style="mso-ansi-language:EN-US; mso-fareast-language:FR" lang="EN-US"> on regiospecific 1,3-dipolar cycloaddition with [(4-chlorophenyl)methyldyne]azans oxide, prepared in situ, afford the expected new 1,2,4-bis-oxadiazolines 12-22. The target molecules have been identified on the basis of satisfactory analytical results and <span style="mso-fareast-font-family:AdvEPSTIM; mso-ansi-language:EN-US" lang="EN-US">characterized by spectroscopic means (1H NMR, 13C NMR, UV, IR, HRMS and elemental analyses). All the previously unknown compounds 12-22 have been screened for their antifungal activity towards Trichoderma harzianum, <i style="mso-bidi-font-style: normal">Botrytis cinerea, Fusarium sambucinum and Penicillium sp. using the disc diffusion<span style="mso-fareast-font-family: AdvGulliv-R;mso-ansi-language:EN-US" lang="EN-US"> <span style="mso-ansi-language: EN-US" lang="EN-US">method. Applied at two concentrations, some of these bis-oxadiazolines exhibit an interesting inhibitory effect against the fungi tested. It is found that compounds, possessing an NO2 group on their aromatic ring, exhibit variable antifungal activity against B. cinerea depending on NO2 position. In fact, the inhibitory activity has been found to be increased when the NO2 group is situated in the meta position. </span

Selection of compost-derived actinomycetes with plant-growth promoting and tomato stem rot biocontrol potentialities

Seventeen actinomycetes isolates, recovered from 2 composts, were screened for their ability to promote the growth of tomato seedlings and to suppress stem rot disease caused by Sclerotium rolfsii. Tomato cv. Rio Grande seedlings inoculated with S. rolfsii and treated with A2-3, A3-3, A4-3, A5-3, A8-3, A9-3, A1-4, A2-4, A3-4, A4-4, A6-4, and A10-4 actinobacterial isolates showed 23.3-70% less disease severity than the inoculated and untreated controls. A3-3, A2-4, and A4-4 based treatments applied to S. rolfsii-infected tomato seedlings had significantly enhanced all growth parameters as compared to control. The recorded increments were estimated at 35.52-66.6% for height, 37.4-53.4% for the stem diameter, 38.5-95.6% for the aerial part dry weight, and 81.8-151% for the root dry weight. Treatments with A3-3 and A4-4 isolates had increased the majority of tomato growth parameters by 15.8-56.5% over the pathogen-free control. Tomato seedlings treated with A4-3 and A1-4 isolates showed between 35.2-22.8% and 42.3-43.3% higher aerial part dry weight and root dry weight, respectively, as compared to pathogen-free and untreated control. This investigation demonstrated that the tested composts can be explored as potential sources for the isolation of actinomycetes acting as biocontrol and bio-fertilizing agents

Control of Root Rot Diseases of Tomato Plants Caused by Fusarium solani, Rhizoctonia solani and Sclerotium rolfsii Using Different Chemical Plant Resistance Inducers

Root rots of tomato plants caused by Rhizoctonia solani, Fusarium solani and Sclerotium rolfsii are serious diseases leading to delayed growth and subsequent death of severely infected plants. Effect of some chemical inducers such as potassium salts, salicylic acid and sorbic acid on control of root rot pathogens and their impact on growth, quantity and quality parameters of tomato cv. Super Strain B were investigated. All the tested chemical inducers significantly reduced severity of root rots under greenhouse and field conditions. Potassium salts based-treatments, followed by salicylic acid, were the most effective in decreasing incidence of root rots induced by all tested pathogens. However, sorbic acid was found to be the least effective treatment. In field trials, the highest reductions of root rot incidence and disease severity were recorded on tomato plants treated with potassium sorbate used at 7.5% and dipotassium hydrogen phosphate (K2HPO4 ) 400 mM followed by salicylic acid 100 mM treatment. Disease incidence and severity were reduced by 65.4 and 62.5% in 2012, and by 63.2 and 53.8% in 2013 cropping seasons, respectively. Application of potassium salts followed by salicylic acid was the most efficient for the increase of growth parameters, yield and quality of tomato fruits while compared to control. Therefore, it could be suggested that application of plant chemical resistance inducers could be commercially used for controlling tomato root rot diseases and increasing both quality and quantity of tomato since they are safe, less expensive and effective against these diseases even under field conditions

Chitosan and Trichoderma harzianum as Fungicide Alternatives for Controlling Fusarium Crown and Root Rot of Tomato

Tomato is one of the most important vegetable crops in Egypt and Tunisia. Fusarium crown and root rot (FCRR), caused by Fusarium oxysporum f. sp. radicis-lycopersici (Forl), is one of the most damaging soilborne disease of tomato and is becoming more common in commercial greenhouses. In the present study, effect of individual or combined application of Trichoderma harzianum and chitosan against Forl was assessed in vitro and in vivo. T. harzianum had significantly reduced the mycelial growth of the five Forl tested isolates. Chitosan applied at different concentrations (from 0.5 to 4 g/l) had also significantly decreased the mycelial growth of the pathogen and a total inhibition was obtained at the concentration 4 g/l. Under greenhouse conditions, application of T. harzianum and chitosan (1 g/l) as root dipping treatment combined with chitosan (0.5 g/l) as foliar spray has reduced FCRR incidence and severity by 66.6 and 47.6%, respectively. Treatments based on T. harzianum alone or in combination with chitosan led to an increase in the total phenols and to an enhancement of chitinase and β,1-3-glucanase activities in leaves of treated tomato plants compared with the untreated ones. The results from this study showed the possibility of using combined treatments based on T. harzianum and chitosan commercially as an approach for controlling FCRR on tomato

Bio-suppression of sclerotinia stem rot of tomato and biostimulation of plant growth using tomato-associated rhizobacteria

A collection of 25 rhizobacterial strains, recovered from rhizospheric soils around healthy tomato plants grown in Rhizoctonia-infested fields, belonging to Bacillus amyloliquefaciens, B. thuringiensis, B. megaterium, B. subtilis, Enterobacter cloacae, Chryseobacterium jejuense, and Klebsiella pneumoniae was screened for its suppressive effects of Sclerotinia Stem Rot of tomato caused by Sclerotinia sclerotiorum and plant growth-promoting ability. The inhibitory effects of diffusible and volatile metabolites from these rhizobacteria against pathogen mycelial growth depended significantly upon strains tested. Growth inhibition caused by diffusible and volatile compounds was of about 37-57% and 24-54%, respectively. All strains tested had totally suppressed myceliogenic germination of sclerotia and improved germination of bacterized tomato seeds as compared to the untreated controls. The screening of their disease-suppressive and plant growth-promoting abilities revealed 72-100% decrease in Sclerotinia Stem Rot severity and significant increments in plant height by 52-67%, roots fresh weight by about 66-88% and aerial part weight by 47-75%, compared to S. sclerotiorum-inoculated and untreated control. The most promising strains combining disease-suppressive and growth-promoting abilities were B. subtilis B10 (KT921327) and B14 (KU161090), B. thuringiensis B2 (KU158884), B. amyloliquefaciens B13 (KT951658) and B15 (KT923051), and E. cloacae B16 (KT921429)

Combining potential oomycete and bacterial biocontrol agents as a tool to fight tomato Rhizoctonia root rot

Biological control of Rhizoctonia root rot and growth-promoting potential on two tomato cultivars was performed using Pythium oligandrum in combination, or not, with three tomato-associated rhizobacterial strains of Bacillus subtilis, B. thuringiensis and Enterobacter cloacae. The three bacterial strains displayed antifungal activity against Rhizoctonia solani, with pathogen growth inhibition up to 60%. P. oligandrum also destroyed R. solani cells by antibiosis and mycoparasitism processes. In a three-month greenhouse assays, for all trials and the two tomato cultivars used, disease suppression potential, as compared to the controls, was up to 80% using the microorganisms mixtures and 74% by using P. oligandrum alone. Increased height in disease-free plants was obtained with the microorganism mixtures (59%) compared to P. oligandrum (49%). Plants grown in R. solani inoculated peat and challenged with microorganism mixtures were higher than controls, whereas those amended with P. oligandrum showed 46 to 87% height increase. All treatments with the microorganisms were more effective in suppressing the disease than chemical fungicide. Increment of aerial parts and root fresh weights on disease-free plants were until 51% for those treated with microorganism mixtures compared to 46% recorded using P. oligandrum. On inoculated plants, these parameters were enhanced using the mixed treatment. No differences in the rhizosphere-bacterial populations were observed by Single Strand Conformational Polymorphism (SSCP) when, either the rhizobacteria, with or without P. oligandrum, or the pathogen, were inoculated. This suggests that the native bacterial communities were not significantly impact