Assessing the functional diversity of rhizobacteria from cacao by partitioning root and shoot biomasses.

Plant-microbe interactions are critical for the sustainability of agricultural production. In this study, our aims were to characterize the genetic and functional diversity of the culturable bacterial community associated with the cacao rhizosphere and access their potential for growth promotion of cacao seedling. Culture-dependent and molecular methods were used to characterize the population densities and diversity of bacterial communities from soil and cacao plants at two locations and two plant ages.

The combination of two Bacillus strains suppresses Meloidogyne incognita and fungal pathogens, but does not enhance plant growth.

Background: The combination of biocontrol agents is a desirable strategy to improve control efficacy against the root-knot nematode (RKN) Meloidogyne incognita under field conditions. However, strains compatibility is generally tested in vitro and incompatible combinations are normally not further examined in experiments in planta. Therefore, there is virtually no information on the performance of incompatible strains.

Burkholderia perseverans sp. nov., a bacterium isolated from the Restinga ecosystem, is a producer of volatile and diffusible compounds that inhibit plant pathogens.

Gram-negative, aerobic, rod-shaped, non-spore-forming, motile bacteria, designated CBAS 719, CBAS 732 and CBAS 720 were isolated from leaf litter samples, collected in Espírito Santo State, Brazil, in 2008. Sequences of the 16S rRNA, gyrB, lepA and recA genes showed that these strains grouped with Burkholderia plantarii LMG 9035, Burkholderia gladioli LMG 2216 and Burkholderia glumae LMG 2196 in a clade of phytopathogenic Burkholderia species. Digital DNA-DNA hybridization experiments and ANI analyses demonstrated that strain CBAS 719 represents a novel species in this lineage that is very closely related with B.

The mitochondrial genome of the grape powdery mildew pathogen Erysiphe necator is intron rich and exhibits a distinct gene organization.

Powdery mildews are notorious fungal plant pathogens but only limited information exists on their genomes. Here we present the mitochondrial genome of the grape powdery mildew fungus Erysiphe necator and a high-quality mitochondrial gene annotation generated through cloning and Sanger sequencing of full-length cDNA clones. The E.

Targeted Delivery of Gene Silencing in Fungi Using Genetically Engineered Bacteria.

Exploiting RNA interference (RNAi) in disease control through non-transformative methods that overcome the hurdle of producing transgenic plants has attracted much attention over the last years. Here, we explored such a method and used non-pathogenic bacteria as a versatile system for delivering RNAi to fungi. Specifically, the RNaseIII-null mutant strain of HT115(DE3) was transformed with two plasmid vectors that enabled the constitutive or IPTG-inducible production of double-stranded RNAs (dsRNAs) against genes involved in aflatoxins production in () or virulence of ().

Complete genome sequence of the biocontrol agent Serratia marcescens strain N4-5 uncovers an assembly artefact.

Serratia marcescens are gram-negative bacteria found in several environmental niches, including the plant rhizosphere and patients in hospitals. Here, we present the genome of Serratia marcescens strain N4-5 (=NRRL B-65519), which has a size of 5,074,473 bp (664-fold coverage) and contains 4840 protein coding genes, 21 RNA genes, and an average G + C content of 59.7%.

First-tier detection of intragenomic 16S rRNA gene variation in culturable endophytic bacteria from cacao seeds.

Background: Intragenomic variability in 16S rDNA is a limiting factor for taxonomic and diversity characterization of Bacteria, and studies on its occurrence in natural/environmental populations are scarce. In this work, direct DNA amplicon sequencing coupled with frequent-cutter restriction analysis allowed detection of intragenomic 16S rDNA variation in culturable endophytic bacteria from cacao seeds in a fast and attractive manner.

Methods: Total genomic DNA from 65 bacterial strains was extracted and the 16S rDNA hyper variable V5-V9 regions were amplified for enzyme digestion and direct Sanger-type sequencing.

Characterization of genetic diversity on tropical Trichoderma germplasm by sequencing of rRNA internal transcribed spacers.

Objective: Trichoderma species are found in soil and in association with plants. They can act directly or indirectly in the biological control of plant diseases and in the promotion of plant growth, being among the most used fungi in the formulation of bioproducts applied to agricultural systems. The main objective of this study was to characterize at a first-tier level a collection of 67 Trichoderma isolates from various tropical sources, based solely on sequencing of the internal transcribed spacer (ITS) region of the rRNA genes.

Complete Genome Sequence of the Biocontrol Agent Bacillus velezensis UFLA258 and Its Comparison with Related Species: Diversity within the Commons.

In this study, the full genome sequence of Bacillus velezensis strain UFLA258, a biological control agent of plant pathogens was obtained, assembled, and annotated. With a comparative genomics approach, in silico analyses of all complete genomes of B. velezensis and closely related species available in the database were performed.

Bio-based products control black rot (Xanthomonas campestris pv. campestris) and increase the nutraceutical and antioxidant components in kale.

Black rot of crucifers, (Xanthomonas campestris pv. campestris) is the principal yield-limiting and destructive pathogen of cruciferous crop worldwide. In order to validate a bio-based control alternative for this disease, whey, lime sulfur, biofertilizer, Bordeaux mixture or raw milk were applied to kale (Brassica oleracea var.

Environmental Growth Conditions of spp. Affects Indole Acetic Acid Derivatives, Volatile Organic Compounds, and Plant Growth Promotion.

species are soil-borne filamentous fungi widely utilized for their many plant health benefits, such as conferring improved growth, disease resistance and abiotic stress tolerance to their hosts. Many species are able to produce the auxin phytohormone indole-3-acetic acid (IAA), and its production has been suggested to promote root growth. Here we show that the production of IAA is strain dependent and diverse external stimuli are associated with its production.

High-Quality Draft Genome Sequence of Bacillus amyloliquefaciens Strain 629, an Endophyte from Theobroma cacao.

Bacillus amyloliquefaciens strain 629 is an endophyte isolated from Theobroma cacao L. Here, we report the draft genome sequence (3.9 Mb) of B.

Bacillus subtilis and Enterobacter cloacae endophytes from healthy Theobroma cacao L. trees can systemically colonize seedlings and promote growth.

Clonal genotypes resistant to fungal diseases are an important component of the cocoa production system in southeastern Bahia state (Brazil), so that technologies for faster production of stronger and healthier plantlets are highly desirable. In this study, the effects of inoculated bacterial endophytes isolated from healthy adult cacao plants on seedlings, and aspects related to inoculation methods, colonization patterns, and photosynthesis were investigated. Sequencing of 16S rRNA, hsp-60, and rpo-B genes placed the wild-type isolates within the species Enterobacter cloacae (isolates 341 and 344) and Bacillus subtilis (isolate 629).

Genetic and Biological Diversity of Trichoderma stromaticum, a Mycoparasite of the Cacao Witches'-Broom Pathogen.

ABSTRACT The witches'-broom disease, caused by the basidiomycete Crinipellis perniciosa, is the most limiting factor for cacao cultivation in Brazil. Trichoderma stromaticum is a mycoparasite of the witches'-broom pathogen of cacao that is currently being applied in the field to manage the disease in Bahia State, Brazil. In this work, molecular and traditional methods were used to study the genetic and biological diversity of this mycoparasite.

Frequency, Diversity, and Activity of 2,4-Diacetylphloroglucinol-Producing Fluorescent Pseudomonas spp. in Dutch Take-all Decline Soils.

ABSTRACT Natural suppressiveness of soils to take-all disease of wheat, referred to as take-all decline (TAD), occurs worldwide. It has been postulated that different microbial genera and mechanisms are responsible for TAD in soils from different geographical regions. In growth chamber experiments, we demonstrated that fluorescent Pseudomonas spp.

Effect of 2,4-diacetylphloroglucinol on pythium: cellular responses and variation in sensitivity among propagules and species.

ABSTRACT The antibiotic 2,4-diacetylphloroglucinol (2,4-DAPG) plays an important role in the suppression of plant pathogens by several strains of Pseudomonas spp. Based on the results of this study, there is variation within and among Pythium spp. to 2,4-DAPG.

Population densities and genetic diversity of actinomycetes associated to the rhizosphere of Theobroma cacao.

In spite of the acknowledged importance of growth-promoting bacteria, only a reduced number of studies were conducted with these microorganisms on Theobroma cacao. The objectives of this work were to study the population densities and genetic diversity of actinomycetes associated with the rhizosphere of cacao as a first step in their application in plant growth promotion and biological control. The populations densities of actinomycetes in soil and cacao roots were similar, with mean values of 1,0 x 10(6) CFU/g and 9,6 x 10(5) CFU/g, respectively.

Role of sdhA and pfkA and catabolism of reduced carbon during colonization of cucumber roots by Enterobacter cloacae.

We have been using a mutational approach to determine how plant-beneficial bacteria such as Enterobacter cloacae 501R3 obtain carbon and energy for colonization of subterranean portions of cucumber and other plants. Reduced carbon detected in cucumber root exudate consisted of 73.3 % amino acids, 22.

Mutation in cyaA in Enterobacter cloacae decreases cucumber root colonization.

Strains of Enterobacter cloacae show promise as biological control agents for Pythium ultimum-induced damping-off on cucumber and other crops. Enterobacter cloacae M59 is a mini-Tn5 Km transposon mutant of strain 501R3. Populations of M59 were significantly lower on cucumber roots and decreased much more rapidly than those of strain 501R3 with increasing distance from the soil line.

Biochemical, genetic, and zoosporicidal properties of cyclic lipopeptide surfactants produced by Pseudomonas fluorescens.

Zoospores play an important role in the infection of plant and animal hosts by oomycetes and other zoosporic fungi. In this study, six fluorescent Pseudomonas isolates with zoosporicidal activities were obtained from the wheat rhizosphere. Zoospores of multiple oomycetes, including Pythium species, Albugo candida, and Phytophthora infestans, were rendered immotile within 30 s of exposure to cell suspensions or cell culture supernatants of the six isolates, and subsequent lysis occurred within 60 s.

Antibiotic production by bacterial biocontrol agents.

Interest in biological control of plant pathogens has been stimulated in recent years by trends in agriculture towards greater sustainability and public concern about the use of hazardous pesticides. There is now unequivocal evidence that antibiotics play a key role in the suppression of various soilborne plant pathogens by antagonistic microorganisms. The significance of antibiotics in biocontrol, and more generally in microbial interactions, often has been questioned because of the indirect nature of the supporting evidence and the perceived constraints to antibiotic production in rhizosphere environments.