Rhizosphere plant-microbe interactions under water stress.

Climate change, with its extreme temperature, weather and precipitation patterns, is a major global concern of dryland farmers, who currently meet the challenges of climate change agronomically and with growth of drought-tolerant crops. Plants themselves compensate for water stress by modifying aerial surfaces to control transpiration and altering root hydraulic conductance to increase water uptake. These responses are complemented by metabolic changes involving phytohormone network-mediated activation of stress response pathways, resulting in decreased photosynthetic activity and the accumulation of metabolites to maintain osmotic and redox homeostasis.

Root Exudates Alter the Expression of Diverse Metabolic, Transport, Regulatory, and Stress Response Genes in Rhizosphere .

Plants live in association with microorganisms that positively influence plant development, vigor, and fitness in response to pathogens and abiotic stressors. The bulk of the plant microbiome is concentrated belowground at the plant root-soil interface. Plant roots secrete carbon-rich rhizodeposits containing primary and secondary low molecular weight metabolites, lysates, and mucilages.

Draft Genome Sequences of Xylella fastidiosa subsp. Strains OK3, VB11, and NOB1, Isolated from Bunch and Muscadine Grapes Grown in Southern Mississippi.

We report here high-quality draft whole-genome assemblies of subsp. strains OK3, VB11, and NOB1, which were isolated from symptomatic bunch and muscadine grape plants grown in southern Mississippi.

Comparative Analysis of Rhizosphere Microbiomes of Southern Highbush Blueberry ( L.), Darrow's Blueberry ( Camp), and Rabbiteye Blueberry ( Aiton).

Plants are inhabited by millions of parasitic, commensal, and mutualistic microorganisms that coexist in complex ecological communities, and profoundly affect the plant's productivity, health, and capacity to cope with environmental stress. Therefore, a better understanding of the rhizosphere microbiome may open a yet untapped avenue for the rational exploitation of beneficial plant-microbe interactions in modern agriculture. Blueberries encompass several wild and cultivated species of shrubs of the genus that are native to North America.

2-79 Transformed with Pyrrolnitrin Biosynthesis Genes Has Improved Biocontrol Activity Against Soilborne Pathogens of Wheat and Canola.

A four-gene operon () from Pf-5 encoding the biosynthesis of the antibiotic pyrronitrin was introduced into (formerly ) 2-79, an aggressive root colonizer of both dryland and irrigated wheat roots that naturally produces the antibiotic phenazine-1-carboxylic acid and suppresses both take-all and Rhizoctonia root rot of wheat. Recombinant strains ZHW15 and ZHW25 produced both antibiotics and maintained population sizes in the rhizosphere of wheat that were comparable to those of strain 2-79. The recombinant strains inhibited in vitro the wheat pathogens anastomosis group 8 (AG-8) and AG-2-1, var.

Exploring the Pathogenicity of Q8r1-96 and Other Strains of the Complex on Tomato.

and related species of the complex have long been studied as biocontrol and growth-promoting rhizobacteria involved in suppression of soilborne pathogens. We report here that Q8r1-96 and other 2,4-diacetylphloroglucinol (DAPG)-producing fluorescent pseudomonads involved in take-all decline of wheat in the Pacific Northwest of the United States can also be pathogenic to other plant hosts. Strain Q8r1-96 caused necrosis when injected into tomato stems and immature tomato fruits, either attached or removed from the plant, but lesion development was dose dependent, with a minimum of 10 CFU ml required to cause visible tissue damage.

Antimicrobial Activity of, and Cellular Pathways Targeted by, -Anisaldehyde and Epigallocatechin Gallate in the Opportunistic Human Pathogen Pseudomonas aeruginosa.

Plant-derived aldehydes are constituents of essential oils that possess broad-spectrum antimicrobial activity and kill microorganisms without promoting resistance. In our previous study, we incorporated -anisaldehyde from star anise into a polymer network called proantimicrobial networks via degradable acetals (PANDAs) and used it as a novel drug delivery platform. PANDAs released -anisaldehyde upon a change in pH and humidity and controlled the growth of the multidrug-resistant pathogen PAO1.

Discovery and Characterization of Bacteriophage LuckyBarnes.

Here, we report the genome sequence of LuckyBarnes, a newly isolated singleton siphovirus that infects ATCC 15728 and has a 50,774-bp genome with 67 predicted genes.

Rhizosphere Microbial Communities of and From Restored and Natural Tidal Marshes on Deer Island, Mississippi.

The U. S. Gulf of Mexico is experiencing a dramatic increase in tidal marsh restoration actions, which involves planting coastal areas with smooth cordgrass () and black needlerush () for erosion control and to provide habitat for fish and wildlife.

Differential Response of Wheat Cultivars to Pseudomonas brassicacearum and Take-All Decline Soil.

2,4-Diacetylphloroglucinol (DAPG)-producing Pseudomonas spp. in the P. fluorescens complex are primarily responsible for a natural suppression of take-all of wheat known as take-all decline (TAD) in many fields in the United States.

Phenazine-1-carboxylic acid and soil moisture influence biofilm development and turnover of rhizobacterial biomass on wheat root surfaces.

Phenazine-1-carboxylic acid (PCA) is produced by rhizobacteria in dryland but not in irrigated wheat fields of the Pacific Northwest, USA. PCA promotes biofilm development in bacterial cultures and bacterial colonization of wheat rhizospheres. However, its impact upon biofilm development has not been demonstrated in the rhizosphere, where biofilms influence terrestrial carbon and nitrogen cycles with ramifications for crop and soil health.

Long-Term Irrigation Affects the Dynamics and Activity of the Wheat Rhizosphere Microbiome.

The Inland Pacific Northwest (IPNW) encompasses 1. 6 million cropland hectares and is a major wheat-producing area in the western United States. The climate throughout the region is semi-arid, making the availability of water a significant challenge for IPNW agriculture.

A bio-based pro-antimicrobial polymer network via degradable acetal linkages.

Unlabelled: The synthesis of a fully degradable, bio-based, sustained release, pro-antimicrobial polymer network comprised of degradable acetals (PANDA) is reported. The active antimicrobial agent - p-anisaldehyde (pA) (an extract from star anise) - was converted into a UV curable acetal containing pro-antimicrobial monomer and subsequently photopolymerized into a homogenous thiol-ene network. Under neutral to acidic conditions (pH < 8), the PANDAs undergo surface erosion and exhibit sustained release of pA over 38 days.

Draft genome sequences of strains SMB35, sp. MH3R3-1 and sp. SMB17 from the Verkhnekamsk potash mining region of Russia.

Halomonads are moderately halophilic bacteria that are studied as models of prokaryotic osmoadaptation and sources of enzymes and chemicals for biotechnological applications. Despite the progress in understanding the diversity of these organisms, our ability to explain ecological, metabolic, and biochemical traits of halomonads at the genomic sequence level remains limited. This study addresses this gap by presenting draft genomes of SMB35, sp.

Genome Sequence of Mycobacterium Phage Waterfoul.

Waterfoul is a newly isolated temperate siphovirus of Mycobacterium smegmatis mc155. It was identified as a member of the K5 cluster of Mycobacterium phages and has a 61,248-bp genome with 95 predicted genes.

Draft Genome Sequence of the Phenazine-Producing Pseudomonas fluorescens Strain 2-79.

Pseudomonas fluorescens strain 2-79, a natural isolate of the rhizosphere of wheat (Triticum aestivum L.), possesses antagonistic potential toward several fungal pathogens. We report the draft genome sequence of strain 2-79, which comprises 5,674 protein-coding sequences.

Biocontrol and plant growth-promoting activity of rhizobacteria from Chinese fields with contaminated soils.

The aim of this study was to inventory the types of plant growth-promoting rhizobacteria (PGPR) present in the rhizosphere of plants grown in soils contaminated with heavy metals, recalcitrant organics, petroleum sewage or salinity in China. We screened 1223 isolates for antifungal activity and about 24% inhibited Rhizoctonia solani or Sclerotinia sclerotiorum. Twenty-four strains inhibitory to R.

Pseudomonas protegens Pf-5 causes discoloration and pitting of mushroom caps due to the production of antifungal metabolites.

Bacteria in the diverse Pseudomonas fluorescens group include rhizosphere inhabitants known for their antifungal metabolite production and biological control of plant disease, such as Pseudomonas protegens Pf-5, and mushroom pathogens, such as Pseudomonas tolaasii. Here, we report that strain Pf-5 causes brown, sunken lesions on peeled caps of the button mushroom (Agaricus bisporus) that resemble brown blotch symptoms caused by P. tolaasii.

Biological control of wheat root diseases by the CLP-producing strain Pseudomonas fluorescens HC1-07.

Pseudomonas fluorescens HC1-07, previously isolated from the phyllosphere of wheat grown in Hebei province, China, suppresses the soilborne disease of wheat take-all, caused by Gaeumannomyces graminis var. tritici. We report here that strain HC1-07 also suppresses Rhizoctonia root rot of wheat caused by Rhizoctonia solani AG-8.

Trapped intermediates in crystals of the FMN-dependent oxidase PhzG provide insight into the final steps of phenazine biosynthesis.

Phenazines are redox-active secondary metabolites that many bacteria produce and secrete into the environment. They are broad-specificity antibiotics, but also act as virulence and survival factors in infectious diseases. Phenazines are derived from chorismic acid, but important details of their biosynthesis are still unclear.

pA506, a conjugative plasmid of the plant epiphyte Pseudomonas fluorescens A506.

Conjugative plasmids are known to facilitate the acquisition and dispersal of genes contributing to the fitness of Pseudomonas spp. Here, we report the characterization of pA506, the 57-kb conjugative plasmid of Pseudomonas fluorescens A506, a plant epiphyte used in the United States for the biological control of fire blight disease of pear and apple. Twenty-nine of the 67 open reading frames (ORFs) of pA506 have putative functions in conjugation, including a type IV secretion system related to that of MOBP6 family plasmids and a gene cluster for type IV pili.