Medium optimization for the feather-degradation by <Emphasis Type="Italic">Streptomyces fradiae Var</Emphasis><Emphasis Type="Italic">S-221</Emphasis> using the response surface methodology

In order to accelerate biodegradation of feather into more amino acids, the fermentation medium of feather-biodegrading Streptomyces fradiae Var S-221 was optimized in this paper. In the first optimization step, the effects of feather powder, beet molasses, (NH₄)₂SO₄ and KH₂PO₄ on amino acids formation were evaluated by using full factorial design. The results showed that feather powder and (NH₄)₂SO₄ had significant and positive effects on feather-biodegradation into amino acids. Then, the method of the steepest ascent was used to access the optimal region of the two significant factors. In the third step, the concentration of feather powder and (NH₄)₂SO₄ were further optimized with central composite design and response surface analysis. As a result, the composition of the optimal medium for S. fradiae Var S-221 fermentation were as follows (g/100 ml): feather powder, 19.504; beet molasses, 4.0; (NH₄)₂SO₄, 1.467; KH₂PO₄, 0.3; MgSO₄, 0.15; FeSO₄, 0.001; ZnSO₄, 0.0001; and MnSO₄, 0.0001. Using this optimal fermentation medium, the amino acids concentration was increased from 4.61 to 6.13 g/100 ml.     

Orthogonal array design for optimization of an artificial medium for in vitro rearing of Trichogramma dendrolimi

Successful complete development of Trichogramma species on artificial media is also related to the presence and proportions of ingredients other than host insect‐derived components. In this study, an orthogonal array with six factors at three levels was performed and parameters of parasitism, larval development, pupation, and adult emergence were monitored to reveal the most important components of an artificial medium and to improve the medium for in vitro mass rearing of Trichogramma dendrolimi Matsumura (Hymenoptera: Trichogrammatidae). Results indicated that biological parameters of T. dendrolimi were affected differently by six ingredients of the artificial medium: pupal hemolymph of Antheraea pernyi (Guérin‐Méneville) (Lepidoptera: Saturniidae), egg yolk, 10% malted milk solution, Neisenheimer's salt solution, trehalose, and sterile water. Statistical analysis indicated that trehalose and Neisenheimer's salt solution, 10% malted milk solution, and pupal hemolymph of A. pernyi were the main ingredients of the artificial medium based on rates of parasitism and pupation, the number of larvae developing in each artificial egg, adult emergence rate, and the number of normal adults produced. A follow‐up bioassay with a selection of optimized formulas confirmed the validity of the optimization as predicted by the orthogonal array analysis, indicating the usefulness of this method for selecting artificial diets for entomophagous insects. Adult emergence rate of the parasitoid and total number of normal adults produced per egg card (each containing 20 artificial eggs) averaged 88.8% and 956 females on the best performing optimized artificial medium, consisting of 3 ml pupal hemolymph of A. pernyi, 2.5 ml egg yolk, 1 ml 10% malted milk solution, 1 ml Neisenheimer's salt solution, 0.1 g trehalose, and 1.5 ml sterile water. The latter medium was superior to any formerly developed medium and may thus have potential for the in vitro mass rearing of T. dendrolimi.     

Optimization of actinomycin V production by Streptomyces triostinicus using artificial neural network and genetic algorithm

Artificial neural network (ANN) and genetic algorithm (GA) were applied to optimize the medium components for the production of actinomycinV from a newly isolated strain of Streptomyces triostinicus which is not reported to produce this class of antibiotics. Experiments were conducted using the central composite design (CCD), and the data generated was used to build an artificial neural network model. The concentrations of five medium components (MgSO₄, NaCl, glucose, soybean meal and CaCO₃) served as inputs to the neural network model, and the antibiotic yield served as outputs of the model. Using the genetic algorithm, the input space of the neural network model was optimized to find out the optimum values for maximum antibiotic yield. Maximum antibiotic yield of 452.0 mg l⁻¹ was obtained at the GA-optimized concentrations of medium components (MgSO₄ 3.657; NaCl 1.9012; glucose 8.836; soybean meal 20.1976 and CaCO₃ 13.0842 gl⁻¹). The antibiotic yield obtained by the ANN/GA was 36.7% higher than the yield obtained with the response surface methodology (RSM).     

A chitinase with antifungal activity from the mung bean

A chitinase with antifungal activity was isolated from mung bean (Phaseolus mungo) seeds. The procedure entailed aqueous extraction, (NH₄)₂SO₄ precipitation, ion-exchange chromatography on CM-Sepharose, high-performance liquid chromatography (HPLC) on Poros HS-20, and gel filtration on Sephadex G-75. The protein exhibited a molecular mass of 30.8 kDa in SDS–polyacrylamide gel electrophoresis. Its pI was 6.3 as determined by isoelectric focusing. The specific activity of the chitinase was estimated to be 3.81 U/mg. The enzyme expressed its optimum activity at pH 5.4 and was stable from 40 to 50 °C. It exerted antifungal action toward Fusarium solani, Fusarium oxysporum, Mycosphaerella arachidicola, Pythium aphanidermatum, and Sclerotium rolfsii.     

Bacterial iturins mediate biocontrol activity of Bacillus sp. against postharvest pear fruit‐rotting fungi

A potential antagonist, Bacillus sp. LYLB4 isolated from pear fruits, was tested for its antifungal activity against postharvest pear pathogens. LYLB4 had a remarkable antifungal effect on Botryosphaeria dothidea. Although it showed a weak inhibition effect on the growth of Rhizopus stolonifer on potato dextrose agar (PDA) plates, LYLB4 almost completely destroyed R. stolonifer during direct contact in potato dextrose broth (PDB). LYLB4 treatment was able to significantly reduce disease incidence (by 68.9% and 100%, respectively) and lesion diameter (by 68.7% and 100%, respectively) of ring rot caused by B. dothidea and soft rot caused by R. stolonifer in pears. LYLB4 also suppressed several other phytopathogens in vitro, suggesting a broad‐spectrum antagonistic activity against fungal pathogens. 16S rRNA and gyrA sequence analysis indicated that LYLB4 is closely related to B. velezensis. Genome mining indicated that LYLB4 had 11 secondary metabolites encoding clusters, but that the surfactin and fengycin gene clusters may not be functional because of a large deletion. Matrix‐assisted laser desorption ionization‐time of flight mass spectra (MALDI‐TOF‐MS) demonstrated that iturins were the major lipopeptides, and that C₁₆/C₁₇ Bacillomycin D synthesis was stimulated when LYLB4 was co‐cultured with B. dothidea compared to the control. Overall, these results demonstrate that the main biocontrol mechanism adopted by LYLB4 could be through the production of toxic metabolites and direct contact with pathogens.     

Chemical Composition,Antioxidant Properties, α‐Glucosidase Inhibitory,and Antimicrobial Activity of Essential Oils from Acacia mollissima and Acacia cyclops Cultivated in Tunisia

The genus Acacia is quite large and can be found in the warm subarid and arid parts, but little is known about its chemistry, especially the volatile parts. The volatile oils from fresh flowers of A. mollissima and A. cyclops (growing in Tunisia) obtained by hydrodistillation were analyzed by GC then GC/MS. Eighteen (94.7% of the total oil composition) and 23 (97.4%) compounds were identified in these oils, respectively. (E,E)‐α‐Farnesene (51.5%) and (E)‐cinnamyl alcohol (10.7%) constituted the major compounds of the flower oil of A. mollissima, while nonadecane (29.6%) and caryophyllene oxide (15.9%) were the main constituents of the essential oil of A. cyclops. Antioxidant activity of the isolated oils was studied by varied assays, i.e., 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) and 2,2‐azinobis 3‐ethylbenzothiazoline‐6‐sulfonic acid (ABTS); the isolated oils showed lowest IC₅₀ (4 – 39 μg/ml) indicating their high antioxidant activity. The α‐glucosidase inhibitor activity was also evaluated and Acacia oils were found to be able to strongly inhibit this enzyme with IC₅₀ values (81 – 89 μg/ml) very close to that of acarbose which was used as positive control. Furthermore, they were tested against five Gram‐positive and Gram‐negative bacteria and one Candida species. Essential oil of A. mollissima was found to be more active than that of A. cyclops, especially against Pseudomonas aeruginosa (MIC = 0.31 mg/ml and MBC = 0.62 mg/ml).     

Production and Application of Syringomycin E as an Organic Fungicide Seed Protectant against Pythium Damping‐off

Syringomycin E (SRE) is a cyclic lipodepsinonapeptide with potent antifungal activity and is produced by certain strains of Pseudomonas syringae pv. syringae. In this study, its potential as an organic‐compatible agrofungicide and vegetable seed treatment against the soilborne pathogen Pythium ultimum var. ultimum was examined. A variant of P. syringae pv. syringae strain B301D with enhanced SRE‐producing capabilities was isolated and grown in a bioreactor with SRE yields averaging 50 mg/l in 40 h. SRE was extracted and purified through a large‐scale chromatography system using organic‐compatible processes and reagents. The minimum concentrations of the purified product required to inhibit 50 and 90% of P. ultimum oospore germination were determined as 31.3 and 250 μg/ml, respectively. Drench treatment of cucumber seeds in P. ultimum‐infested potting medium (500 oospores/g) with 50 μg/ml SRE or water with no SRE resulted in 90.2 ± 4.5% and 65.7 ± 4.6% germination rates, respectively. Seed coating with 0.03% (w/w) SRE allowed 65.7 ± 4.6% seedlings to germinate on naturally infested soil while 100.0 ± 0.0% of non‐coated seeds were unable to germinate due to Pythium infection. Organic‐compatible and scalably produced SRE is potentially a novel organic fungicide seed protectant.     

Antifungal Monoterpene Derivatives from the Plant Endophytic Fungus Pestalotiopsis foedan

A new monoterpene lactone, (1R,4R,5R,8S)‐8‐hydroxy‐4,8‐dimethyl‐2‐oxabicyclo[3.3.1]nonan‐3‐one ( 1 ), along with one related known compound, (2R)‐2‐[(1R)‐4‐methylcyclohex‐3‐en‐1‐yl]propanoic acid ( 2 ), were isolated from the liquid culture of the plant endophytic fungus Pestalotiopsis foedan obtained from the branch of Bruguiera sexangula. The structure and absolute configuration of 1 were determined on the basis of extensive analysis of NMR spectra combined with computational methods via calculation of the optical rotation (OR) and ¹³C‐NMR. Both compounds exhibited strong antifungal activities against Botrytis cinerea and Phytophthora nicotianae with MIC values of 3.1 and 6.3 μg/ml, respectively, which are comparable to those of the known antifungal drug ketoconazole. Compound 2 also showed modest antifungal activity against Candida albicans with a MIC value of 50 μg/ml.     

Mixed Infection and Natural Spread of ‘Candidatus Phytoplasma asteris’ and Mungbean Yellow Mosaic India Virus Affecting Soya Bean Crop in India

Suspected phytoplasma and virus‐like symptoms of little leaf, yellow mosaic and witches’ broom were recorded on soya bean and two weed species (Digitaria sanguinalis and Parthenium hysterophorus), at experimental fields of Indian Agricultural Research Institute, New Delhi, India, in August–September 2013. The phytoplasma aetiology was confirmed in symptomatic soya bean and both the weed species by direct and nested PCR assays with phytoplasma‐specific universal primer pairs (P1/P6 and R16F2n/R16R2n). One major leafhopper species viz. Empoasca motti Pruthi feeding on symptomatic soya bean plants was also found phytoplasma positive in nested PCR assays. Sequencing BLASTn search analysis and phylogenetic analysis revealed that 16Sr DNA sequences of phytoplasma isolates of soya bean, weeds and leafhoppers had 99% sequence identity among themselves and were related to strains of ‘Candidatus Phytoplasma asteris’. PCR assays with Mungbean yellow mosaic India virus (MYMIV) coat‐protein‐specific primers yielded an amplicon of approximately 770 bp both from symptomatic soya bean and from whiteflies (Bemisia tabaci) feeding on soya bean, confirmed the presence of MYMIV in soya bean and whitefly. Hence, this study suggested the mixed infection of MYMIV and ‘Ca. P. asteris’ with soya bean yellow leaf and witches’ broom syndrome. The two weed species (D. sanguinalis and P. hysterophorus) were recorded as putative alternative hosts for ‘Ca. P. asteris’ soya bean Indian strain. However, the leafhopper E. motti was recorded as putative vector for the identified soya bean phytoplasma isolate, and the whitefly (B. tabaci) was identified as vector of MYMIV which belonged to Asia‐II‐1 genotype.     

Chemical Composition,Antibacterial, Schistosomicidal,and Cytotoxic Activities of the Essential Oil of Dysphania ambrosioides (L.) Mosyakin & Clemants (Chenopodiaceae)

We have investigated the chemical composition and the antibacterial activity of the essential oil of Dysphania ambrosioides (L.) Mosyakin & Clemants (Chenopodiaceae) (DA‐EO) against a representative panel of cariogenic bacteria. We have also assessed the in vitro schistosomicidal effects of DA‐EO on Schistosoma mansoni and its cytotoxicity to GM07492‐A cells in vitro. Gas chromatography (GC) and gas chromatography‐mass spectrometry (GC/MS) revealed that the monoterpenes cis‐piperitone oxide (35.2%), p‐cymene (14.5%), isoascaridole (14.1%), and α‐terpinene (11.6%) were identified by as the major constituents of DA‐EO. DA‐EO displayed weak activity against Streptococcus sobrinus and Enterococcus faecalis (minimum inhibitory concentration (MIC) = 1000 μg/ml). On the other hand, DA‐EO at 25 and 12.5 μg/ml presented remarkable schistosomicidal action in vitro and killed 100% of adult worm pairs within 24 and 72 h, respectively. The LC₅₀ values of DA‐EO were 6.50 ± 0.38, 3.66 ± 1.06, and 3.65 ± 0.76 μg/ml at 24, 48, and 72 h, respectively. However, DA‐EO at concentrations higher than 312.5 μg/ml significantly reduced the viability of GM07492‐A cells (IC₅₀ = 207.1 ± 4.4 μg/ml). The selectivity index showed that DA‐EO was 31.8 times more toxic to the adult S. mansoni worms than GM07492‐A cells. Taken together, these results demonstrate the promising schistosomicidal potential of the essential oil of Dysphania ambrosioides.     

Production of Chitinase and its Optimization from a Novel Isolate <Emphasis Type="Italic">Serratia marcescens</Emphasis> XJ-01

Production of chitinase from bacteria has distinct advantages over fungi, due to the formation of mycelia of fungi in the later phase of fermentation. A novel chitinase-producing bacterial strain XJ-01 was isolated from the Yulu fishing field of Changsha, Hunan province, China, by enrichment and spread-plate technique, sequentially. Physicochemical characterization and 16S rRNA sequencing revealed that strain XJ-01 belongs to Serratia marcescens. By optimizing the fermentation condition based on L₉(3⁴) orthogonal experimental design, a maximal chitinase activity up to 15.36 U/ml was attained by that stain under the condition: 0.5% (NH₄)₂SO₄ as the nitrogen source, 0.75% colloidal chitin as the carbon source, temperature of 32°C, time of 32 h and pH 8.0.     

Optimization of phytase production by solid substrate fermentation

The production of phytase by three feed-grade filamentous fungi (Aspergillus ficuum NRRL 3135, Mucor racemosus NRRL 1994 and Rhizopus oligosporus NRRL 5905) on four commonly used natural feed ingredients (canola meal, cracked corn, soybean meal, wheat bran) was studied in solid substrate fermentation (SSF). A. ficuum NRRL 3135 had the highest yield [15 IU phytase activity/g dry matter (DM)] on wheat bran. By optimizing the supplementation of wheat bran with starch and (NH₄)₂SO₄, phytase production increased to 25 IU/g DM. Optimization was carried out by Plackett-Burman and central composite experimental designs. Using optimized medium, phytase, phosphatase, alpha-amylase and xylanase production by A. ficuum NRRL 3135 was studied in Erlenmeyer flask and tray SSF. By scaling up SSF from flasks to stationary trays, activities of 20 IU phytase activity/g DM were reproducibly obtained. Electronic Publication     

Composition and Biological Activity of Picea pungens and Picea orientalis Seed and Cone Essential Oils

The increasing consumption of natural products lead us to discover and study new plant materials, such as conifer seeds and cones, which could be easily available from the forest industry as a waste material, for their potential uses. The chemical composition of the essential oils of Picea pungens and Picea orientalis was fully characterized by GC and GC/MS methods. Seed and cone oils of both tree species were composed mainly of monoterpene hydrocarbons, among which limonene, α‐ and β‐pinene were the major, but in different proportions in the examined conifer essential oils. The levorotary form of chiral monoterpene molecules was predominant over the dextrorotary form. The composition of oils from P. pungens seeds and cones was similar, while the hydrodistilled oils of P. orientalis seeds and cones differed from each other, mainly by a higher amount of oxygenated derivatives of monoterpenes and by other higher molar mass terpenes in seed oil. The essential oils showed mild antimicrobial action, however P. orientalis cone oil exhibited stronger antimicrobial properties against tested bacterial species than those of P. pungens. Effects of the tested cone essential oils on human skin fibroblasts and microvascular endothelial cells (HMEC‐1) were similar: in a concentration of 0 – 0.075 μl/ml the oils were rather safe for human skin fibroblasts and 0 – 0.005 μl/ml for HMEC‐1 cells. IC₅₀ value of Picea pungens oils was 0.115 μl/ml, while that of Picea orientalis was 0.105 μl/ml. The value of IC₅₀ of both oils were 0.035 μl/ml for HMEC‐1 cells. The strongest effect on cell viability had the oil from Picea orientalis cones, while on DNA synthesis the oil from Picea pungens cones.     

Chemical Composition and Allelopathic,Antibacterial, Antifungal,and Antiacetylcholinesterase Activity of Fish‐mint (Houttuynia cordataThunb.) from India

Fish‐mint (Houttuynia cordataThunb .), belonging to family Saururaceae, has long been used as food and traditional herbal medicine. The present study was framed to assess the changes occurring in the essential‐oil composition of H. cordata during annual growth and to evaluate allelopathic, antibacterial, antifungal, and antiacetylcholinesterase activities. The essential‐oil content ranged from 0.06 – 0.14% and 0.08 – 0.16% in aerial parts and underground stem, respectively. The essential oils were analysed by GC‐FID, GC/MS, and NMR (¹H and ¹³C). Major constituents of aerial‐parts oil was 2‐undecanone (19.4 – 56.3%), myrcene (2.6 – 44.3%), ethyl decanoate (0.0 – 10.6%), ethyl dodecanoate (1.1 – 8.6%), 2‐tridecanone (0.5 – 8.3%), and decanal (1.1 – 6.9%). However, major constituents of underground‐stem oil were 2‐undecanone (29.5 – 42.3%), myrcene (14.4 – 20.8%), sabinene (6.0 – 11.1%), 2‐tridecanone (1.8 – 10.5%), β‐pinene (5.3 – 10.0%), and ethyl dodecanoate (0.8 – 7.3%). Cluster analysis revealed that essential‐oil composition varied substantially due to the plant parts and season of collection. The oils exhibited significant allelopathic (inhibition: 77.8 – 88.8%; LD₅₀: 2.45 – 3.05 μl/plate), antibacterial (MIC: 0.52 – 2.08 μl/ml; MBC: bacteriostatic) and antifungal (MIC: 2.08 – 33.33 μl/ml; MFC: 4.16 – 33.33 μl/ml) activities. The results indicate that the essential oil from H. cordata has a significant potential to allow future exploration and exploitation as a natural antimicrobial and allelopathic agent.     

Rapid Diagnosis of Soya Bean Root Rot Caused by Fusarium culmorum Using a Loop‐Mediated Isothermal Amplification Assay

We report a rapid diagnosis of soya bean (Glycine max L.) root rot caused by Fusarium culmorum, using a loop‐mediated isothermal amplification (LAMP) assay. We used the CYP51C gene sequence to design LAMP assay primers specific for F. culmorum. The LAMP assay amplified the target gene efficiently in 60 min at 63°C. The sensitivity of the assay was 100 pg/μl of genomic DNA. Among the tested soya bean pathogens, a positive colour (sky blue) was only observed in the presence of F. culmorum with the addition of hydroxynaphthol blue (HNB) dye prior to amplification, whereas other species isolates showed no colour change. Suspected diseased soya bean samples collected in the field from Jiangsu, Shandong and Anhui provinces and Beijing were diagnosed successfully using the LAMP assay reported here. This study provides a new and readily available method for rapid diagnosis of soya bean root rot caused by F. culmorum.     

Insecticidal and antifeedant effects of two alkaloids from Cynanchum komarovii against larvae of Plutella xylostella L

A bioassay‐guided fractionation of Cynanchum komarovii crude alkaloid extract led to the isolation of two alkaloids. The isolated alkaloids were identified as 7‐demethoxytylophorine (1) and 6‐hydroxyl‐2,3‐dimethoxy phenanthroindolizidine (2) based on the comparison of their spectroscopic characteristics with the literature data. Insecticidal, antifeedant and growth inhibitory effects of these two alkaloids against the 3rd instar larvae of Plutella xylostella L. (Lepidoptera: Plutellidae) were examined. The results showed that alkaloid 1 was more toxic than alkaloid 2 against the 3rd instar larvae of Plutella xylostella L., but both alkaloids were less toxic than the total alkaloid fraction. For antifeedant activity, alkaloid 1 showed AFC₅₀ of 1.82 mg/ml at 24 h after treatment, alkaloid 2 showed 3.89 mg/ml, while total alkaloids showed 1.56 mg/ml. In dipping toxicity test, alkaloids 1 and 2 produced 93.3% and 63.3% mortality at 72 h after treatment, respectively, while total alkaloids produced 96.7% mortality. The LC₅₀ values for alkaloids 1, 2 and the total alkaloids were 3.54, 9.21 and 2.63 mg/ml, respectively. The development of larvae was also inhibited, and the growth inhibition rates at the concentration of 15.00 mg/ml were 92.8%, 78.2% and 98.6% for alkaloids 1, 2 and total alkaloids, respectively, at 72 h after treatment. Compared with antifeedant and dipping effect, the alkaloids 1, 2 and total alkaloid fraction revealed weak feeding toxicity, and their corrected mortality rates at the concentration of 15.00 mg/ml were 60.0%, 40.0% and 63.3% at 7 days after treatment. The LC₅₀ values for alkaloids 1, 2 and total alkaloids were 12.58, 32.37 and 8.88 mg/ml, respectively, at 7 days after treatment.     

Isolation of Cellulolytic Fungi from Waste of Castor (<Emphasis Type="Italic">Ricinus communis</Emphasis> L.)

This is the first report of isolation of fungi present in fatty and defatted castor bean meal as well as the first of crop’s selection to test the cellulolytic potential, in order to verify the diversity and potential of cellulolytic fungi in castor bean waste (Ricinus communis L.). For the screening on solid medium, it was used carboxymethylcellulose (CMC) as the sole carbon source. The microcrystalline cellulose (Avicel) was used as a substrate for submerged fermentation for production of cellobiohydrolase (FPase) and the CMC to produce endoglucanases (CMCase) and β-glycosidases (BG). 189 cultures of fungi were isolated, including 40 species of filamentous fungi and three yeasts. The Aspergillus was the most frequent found genus. Regarding the distribution of isolated species from defatted castor bean meal, the A. niger was the most frequent one; and within the fatty castor bean meal, the Emericela variecolor prevailed among other species. Among the 67 fungal cultures tested in the initial screening on solid media to assess the cellulolytic potential, 54 disclosed Cellulolytic Index (CI) ranging from 1.04 to 6.00 mm. The isolates were selected for enzyme production in liquid medium with values above 2.0 CI. They were obtained with A. japonicus URM5620 FPase activity (4.99 U/ml) and BG (0.05 U/ml), and Rhodotorula glutinis URM5724 activity of CMCase 3.58 U/ml. These cases occurred after 168 h of submersion for both species of fungi. In our study, we could conclude that the castor bean is a promising source of fungi capable of producing cellulolytic enzymes.     

Identification and antifungal activity analysis of two biocontrol antagonists to Colletotrichum musae

Postharvest anthracnose of banana caused by Colletotrichum musae is one of the major diseases resulting in huge economic losses worldwide. To control this disease using biocontrol agents, two antagonistic strains SD7 and NB20 with significant inhibitory effects on mycelial growth and conidial germination of C. musae were identified and evaluated in this study. The inhibitory effects of cell‐free culture filtrates of SD7 and NB20 on conidial germination of C. musae were both 100%, and those on mycelial growth of C. musae were 97.7 ± 0.9% and 95.0 ± 0.6%, respectively. The antifungal activities of cell‐free culture filtrates of both strains were still stable after they were stored at 4°C for 6 months. The control efficacies of cell‐free culture filtrates of SD7 and NB20 on postharvest anthracnose of banana were 55.9 ± 4.1% and 33.2 ± 3.9%, respectively. The disease severity (mean scale value) in banana fruit fingers was significantly lower after the treatment with a cultural suspension of the bacterial strain SD7 (1.4 ± 0.49) or actinomycete strain NB20 (2.0 ± 0.63), compared to that in the control (4.8 ± 0.40). After subculturing for 10 generations, the antifungal efficiency of NB20 remained stable, whereas that of strain SD7 declined obviously. Lastly, based on the morphological, physio‐biochemical and molecular characteristics, the bacterial strain SD7 was identified as Burkholderia cepacia, while the actinomycete strain NB20 was identified as Streptomyces katrae. The results from this study will provide the basis for developing an effective and novel biofungicide to control banana anthracnose disease.     

2,6‐Dimethoxy‐1,4‐Benzoquinone Enhances Resistance Against the Rice Blast Fungus Magnaporthe oryzae

We investigated the effect of 2,6‐dimethoxy‐1,4‐benzoquinone (DMBQ) on induced resistance to Magnaporthe oryzae in rice. DMBQ concentrations greater than 50 μg/ml inhibited spore germination and appressorium formation in M. oryzae. When rice leaves pretreated with 10 μg/ml DMBQ, which did not show antifungal activity against spore germination and appressorium formation of M. oryzae, were inoculated with M. oryzae spores 5 days after DMBQ pretreatment, blast lesion formation was inhibited compared with control leaves pretreated with distilled water. In addition, infection‐inhibiting activity against M. oryzae was significantly enhanced in rice leaf sheaths pretreated with 10 μg/ml DMBQ. H₂O₂ generation was observed in rice leaves pretreated with DMBQ, and PAL, POX, CHS and PR10a were significantly expressed in these leaves. These results suggested that DMBQ can protect rice from blast disease caused by M. oryzae.     

Potassium phosphites in the protection of common bean plants against anthracnose and biochemical defence responses

The aim of this study was to investigate the effectiveness of potassium phosphites for the control of anthracnose and the mode of action of these products on common bean plants against Colletotrichum lindemuthianum, comparing it with the standard resistance inducer acibenzolar‐S‐methyl. The protection of plants against anthracnose was evaluated in greenhouse after treatment with potassium phosphites (Phosphite A and B, 5.0 ml/L), acibenzolar‐S‐methyl (0.25 g/L), or no treatment (control). Two sprayings of the treatments were performed, respectively, at V4 stage (three trifoliate leaves) and at the R5 stage (flower buds present). The inoculation with C. lindemuthianum was performed 5 days after the first spraying. Phosphite formulations A and B reduced the severity of anthracnose by 68.7% and 55.6%, respectively, and the presence of phosphites in the leaf tissues were detected at concentrations between 1 and 3 mm by 7 days after spraying. These same concentrations of phosphites reduced the mycelial growth of C. lindemuthianum in vitro by 15.0% to 25.7%. In addition, the activities of defence enzymes and the levels of phenolic compounds and lignin were assessed. Phosphite treatments enhanced the activity of various enzymes, including superoxide dismutase, peroxidase, chitinase, and β‐1,3‐glucanase, and increased the lignin and a small increase in the levels of soluble phenolics. This study provides evidence that phosphite treatments control anthracnose by acting directly on C. lindemuthianum and by inducing the production of defence responses.