Antibiosis Research Articles

Direct defense of common bean accessions against two-spotted spider mite (Tetranychus urticae Koch.) attack

To find the direct defense of seedling resistance of common beans, by resistant mechanisms, morphological and physiological attributes of ten cultivars (Naz, Dorsa, Akhtar,KS41128, 65-062-107, 65-071-98, 65-071-306, 65-071-410, 65-071-400, and 65-071-405) were evaluated against two-spotted spider mite in 2017 at Bu-Ali Sina university, Hamedan, Iran. Among four kinds of resistant mechanisms such as antixenosis, antibiosis, tolerant tests and PRI index, both antixenosis and tolerance mechanisms determined to be the most accurate tests in the evaluating of common bean resistance against TSSM attack. Germination delay, development and fast growth, early maturity, erected posture, small cotyledon area, the more leaf thickness along with the dark-colored demonstrated were the escape mechanisms of common beans tolerant genotypes against TSSM attack. Some epidermal traits such as the first defense barrier on common bean like hook-shaped and high density of trichome especially on abaxial epidermis by having trapping behavior showed high relation with tolerant genotypes. In fact, in tolerant beans, related-traits to trichome on leaves entrapped the body parts of TSSM such as leg tarsi, mouthpart and ovipositor and prevented to move, feed and reproduction of mites and therefore, these features decreased damage to leaf area of Phaseolus vulgaris as well. The 65-071-98, 65-062-107 genotypes and NAZ, were certainly categorized as the most tolerant cultivars while Akhtar and 65-071-400 were introduced as the most susceptible accessions of common beans, respectively.

Screening of fungal contaminants in banana tissue cultures in Jkuat, Kenya

Tissue culture is prone to high costs of production arising from losses incurred from fungal contamination. The aim of the study was to characterise fungal contaminants and elucidate the exhibited mode of resistance to most preferred sterilants. Twenty nine fungal samples were collected at the different stages of tissue culture growth, using purposive sampling technique. Morphology results were confirmed by molecular characterization using fungal 18S rRNA sequences. Biochemical and antibiosis tests, identification of genes for capsulation and ATP binding Cassete (ABC) transporters, were performed to show the relationship between the fungi and sterilants resistance. Amylases and proteases were highly expressed by all isolates while xylanases and lipases were moderately expressed and esterases were lowly expressed. Only fourteen isolates had antagonistic activity for Candida albicans while nine of them had antagonistic activity for Pseudomonas aeruginosa. Three isolates were both antagonistic for Staphylococcus aureus and for Escherichia coli. Cunninghamella bainieri (10R) recorded a unique antibiosis and extra cellular enzymatic activity (p<0.05). All the isolates were positive for mdr1 gene and three isolates had CAP64 capsule genes. Aspergillus sp., Penincillium sp., Cladosporium sp., Cunninghamella sp. and Fusarium sp. were identified to be the major fungal contaminants of tissue culture banana cultures in JKUAT laboratories. Key words: Tissue culture, 18S rRNA, fungal contaminants, banana cultures.

Antimicrobial peptides and skin barrier function

As a major component of skin, antimicrobial peptides (AMPs) have a broad spectrum of antimicrobial activity. Through multiple signaling pathways, they participate in immunoregulation, maintain normal micro-ecological environment in skin, enhance the function of keratinocytes, and play immunoregulatory roles in skin barrier. The expression level of AMPs is associated with the severity of some infectious and inflammatory skin diseases. AMPs also have broad prospects in the treatment of skin diseases. Key words: Skin; Immunomodulation; Antibiosis; Antimicrobial peptides; Defensins; Barrier

Potencial Farmacoindustrial de Trichoderma harzianum para fins Farmacoterapêuticos

Linhagens de Trichoderma estao bem difundidas nos processos de controle de fitopatogenos, alem disto, para promocao do desenvolvimento e crescimento das culturas onde sao inoculados, estes beneficios dao-se pela gama de processos desempenhados por este organismo, os processos sao classificados em parasitismo, antibiose e competicao, alem de secretarem produtos enzimaticos com acoes degradantes, compostos volateis e antimicrobianos. Por meio de testes de producao enzimatica, confronto em placa, metabolitos volateis e sensibilizacao do agente, os isolados de Trichoderma harzianum mostraram-se como um potente produtor de substâncias antimicrobianas e antifungicas perante Sthaphylococcus aureus , Streptococcus pyogenes , E. coli , Pseudomonas aeruginosa , E. faecalis e Rhodotorula sp., Candida albicans , Candida parapsilosis e Candida lusitaniae . Palavras-chave: antimicrobianos, antifungicas, metabolitos, sensibilizacao.

Antibiosis in the environment

Antibiosis in the environment

EVALUATION OF SOME BACTERIAL ANTAGONISTS FOR BIOLOGICAL CONTROL OF FIRE BLIGHT DISEASE

Antagonistic activities of 120 epiphytic bacterial isolates against Erwinia amylovora were evaluated under laboratory and orchard conditions. Samples were collected at three stages of plant growth during 2009. The hosts were chosen from diseased and healthy pome fruit and stone fruit trees in Alborz, Isfahan and Neishabur regions of Iran. Two in vitro tests including antibiosis and immature fruit assay were performed to identify effective bacterial antagonists. Out of 21 strains, four representative strains encoded Kgh1, Abp2, E11 and E10 showed maximum growth inhibition, growth rate and stability in inhibition. Identification of four bacterial antagonists was confirmed by sequencing their 16S rDNA and performing common biochemical tests. These strains were identified as Pseudomonas fluorescens (E10), Pantoea agglomerans (Abp2), Pseudomonas putida (E11) and Serratia marcescens (Kgh1). Some complementary tests were then conducted to check their antagonistic activity against Erwinia amylovora on pear blossom. In all evaluation procedures, biocontrol effects of Pantoea agglomerans Abp2 and Pseudomonas fluorescens E10 were more promising than those afforded by Pseudomonas putida E11 and Serratia marcescens Kgh1. A one-year field experiment was also carried out on a partially susceptible domestic pear cultivar in an infested orchard in the Karaj region of Iran. The selected bacteria were applied twice at 20% and 80% of blooming. The results showed 46.9% disease occurrence in control plants, while the antagonistic bacteria reduced the disease between 23 and 60%. The field trial the most effective antagonist was P. agglomerans Abp2, while the least effective was S. marcescens Kgh1.

Resistência de variedades de algodão ao curuquerê do algodoeiro Alabama argillacea Hubner (lepidoptera: noctuidae)

Este trabalho teve como objetivo verificar a ocorrência das formas de resistência, tais como: a não preferência para oviposição, a não preferência para alimentação e a antibiose, em variedades de algodoeiro (Gossypium hirsutum L.), à Alabama argillacea (Hubner, 1818), em experimentos de laboratório (27 ± 2 ºC, 70 ± 10% de U.R. e fotofase de 14 horas). Para avaliar a não preferência para oviposição e para a alimentação em teste com chance de escolha, adotou-se o delineamento em blocos casualizados e, no teste sem chance, o inteiramente casualizado. Para avaliar a antibiose, foram fornecidas às larvas, diariamente, folhas das variedades DeltaOpal, NuOpal, FMT 701, FMX 910 e 20 FMX 996. Durante este processo, verificou-se a duração de cada fase do inseto, avaliando-se a massa de larvas aos dez dias de idade, massa de pupas com 24 horas, período larval, pré-pupal e pupal, longevidade de adultos, viabilidade total e fecundidade. As variedades NuOpal e FMT 701 apresentam resistência do tipo não preferência para alimentação. As variedades NuOpal, FMT 701 e FMX 910 apresentam resistência do tipo antibiose em relação a A. argillacea.

Effects of Zinc fertilizer application on the incidence of rice stem borers (Scirpophaga species) (Lepidoptera: Pyralidae) in rice (Oryza sativa L.) crop

Use of fertilizer within plant protection system can prove a key factor for pest management strategy. The effects of Zinc sulfate (33% - Zn) fertilizer on the incidence of rice stem borers (Scirpophaga species) (Lepidoptera: Pyralidae) in rice crop were investigated. The Zn was applied using broadcast method at three levels (20, 25 and 30 kg/ha) in the vicinity of the roots, 30 days after crop transplantation. The results of field experiment on rice cultivars Shadab and Mehak showed that Zn had significant influences on the stem borers population and paddy yield over the unfertilized control. Average yield per hectare was increased at all doses of Zn and by applying it at the rates of 20, 25 and 30 kg/ha, the differences in grain yield were not significant, but production increased significantly over the untreated crop due to varying pest prevalence. With respect to borers incidence, higher dose 30 kg Zn/ha markedly decreased infestation, while, applications at 20 and 25 kg permitted slightly more deadhearts and whiteheads incidence, but differed significantly from unfertilized control. The present study implies that due to suppressive effects of Zn fertilizer on the incidence of the rice stem borers at crop maturity stage increased grain yield, and the use of soil amendments strategy can create an unfavorable environment for pest inducing resistance through anti biosis or feeding inhibition. Key words: Rice, Oryza sativa, Scirpophaga, insect control, rice stem borer, Zinc.

Biomanagement of Root Rot of Pine Seedlings

Studies were conducted on biomanagement of root rot of pine ( Pinus wallichiana ) seedlings during 2008-2009 at Shalimar campus, Srinagar, Kashmir. The pathogens associated with the disease were isolated, morphologically characterized and identified as Fusarium oxysporum f. sp. pini (Schlecht.) Synd. and Hans. and Rhizoctonia solani Kuhn, and F. oxysporum proved more pathogenic. In bioassays all the biocontrol agents tested inhibited the mycelial growth of F. oxysporum and R. solani in dual culture, however, Trichoderma harzianum and T. viride were more effective. Pseudomonas fluorescens showed strong antibiosis and developed zone of inhibition against both the pathogens in vitro . Laccaria laccata caused hyphal lysis of the pathogens in dual culture. In vitro evaluation of the culture filtrate of test antagonists revealed that culture filtrate of P. fluorescens had maximum inhibitory effect on mycelial growth and spore/sclerotial germination of test pathogens followed by T. harzianum , T. viride and L. laccata . Inoculation of T. harzianum , P. fluorescens and L. laccata individually or in combination significantly improved the growth and biomass of Kail pine seedlings in vivo . Combined inoculations of biocontrol agents showed synergistic growth promoting action. Seed germination was improved by the biocontrol agents with drastic reduction by pathogenic microorganisms. Biocontrol agents inoculated individually or in combination reduced the pathogenic effect (root rot) as compared to the control.

Interaction between Eutypa lata and Trichoderma harzianum

Metabolites produced by three strains of Trichoderma harzianum reduced growth of Eutypa lata in vitro. Volatile metabolites produced by T. harzianum were fungistatic towards both isolates of E. lata tested. Growth of some isolates of E. lata was inhibited completely by non-volatile metabolites. Infection by E. lata was reduced in autoclaved grapevine cane segments co-inoculated with spores of T. harzianum and E. lata. Scanning electron microscopic examination of gamma-irradiated cane segments and living cuttings inoculated with T. harzianum and E. lata suggested that antagonism in grapevine wood was mainly by antibiosis. Both the pathogen and the antagonist grew in the xylem vessels and pith parenchyma cells of the wood.

Enhanced Resistance to Three Species of Aphids (Homoptera: Aphididae) in Acremonium Endophyte-Infected Turfgrasses

Association of Acremonium endophytes with enhanced resistance to insects in various turfgrasses was studied using three species of aphids; greenbug, Schizaphis graminum (Rondani); bird cherry-oat aphid, Rhopalosiphum padi (L.); and yellow sugarcane aphid, Sipha flava (Forbes). Choice and no-choice tests were used to test resistance in three to four genotypes each of endophyte-infected and endophyte-free perennial ryegrass, Lolium perenne L.; tall fescue, Festuca arundinacea Schreb.; and three species of fine fescues: hard fescue, F. longifolia Thuill; Chewings fescue, F. rubra L. subsp. commutate Gaud.; and blue fescue, F. glauca Lam. Feeding deterrence and antibiosis were significant in endophyte-infected tall fescue for all turfgrass genotypes and aphids tested, with no aphids surviving after 3 d on infected tall fescue. Feeding deterrence and antibiosis to greenbug and yellow sugarcane aphid were significant in endophyte-infected perennial ryegrass with all genotypes tested. None survived on endophyte-infected perennial ryegrass after 72 h. Resistance to bird cherry-oat aphid was dependent on concentration of endophyte hyphae in the host, with significant resistance observed in genotypes with high concentrations. Resistance in endophyte-infected fine-leaved fescues varied with insect and grass species. Preference was generally not significantly affected, but dramatic differences in survival were found in ‘Ensylva’ strong creeping red fescue, blue fescues, Chewings fescues, and hard fescues. Endophyte-enhanced resistance to insects varies between species of grasses and insects, and within species of grasses, suggesting that each endophyte or endophyte-host genotype complex should be evaluated individually.

Role of Antibiosis in Competition of Erwinia Strains in Potato Infection Courts

[This corrects the article on p. 1225 in vol. 54.].

Antibiosis as a Factor in Vegetation Pafterns

Antibiosis as a Factor in Vegetation Pafterns

ALANINE: CYCLOSERINE ANTAGONISM. III. QUANTITATIVE ASPECTS AND RELATION TO HEATING OF CULTURE MEDIA.

Abstract Inhibition of growth by d-cycloserine of a clinical isolate of Escherichia coli in a synthetic alanine-free broth medium was blocked by the addition of d-alanine in equimolar or greater amounts. Heating a synthetic broth medium containing the l-isomer of alanine to 115 ° C. resulted in subversion of the antibiotic effect of d-cycloserine on E. coli. Comparable heating with d-alanine resulted in loss of capacity for antagonism toward d-cycloserine-mediated antibiosis. Chemical analysis for d-alanine showed that synthetic broth medium containing l-alanine contained d-alanine following autoclave sterilization. Three commercial broth media, in common use for conventional antibacterial agent susceptibility testing, contained d-alanine before and after autoclave sterilization.

Antibiosis among Lactobacilli

Antibiosis among Lactobacilli

Bacteriophage and Antibiosis

Bacteriophage and Antibiosis

Symbiosis, Antibiosis, and Cancer

Symbiosis, Antibiosis, and Cancer