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Polyamines are low molecular weight amines, with versatile and essential functions during the lifespan of prokaryotes and eukaryotes. Modulation of polyamine metabolism under biotic stress has attracted a great deal of interest; however, the precise functions of these amines in plant defence responses to pathogen attack are still poorly understood. Herein we summarise and review important aspects of the regulation of polyamine biosynthesis, catabolism and conjugation under biotic stress that might contribute to improve present‐day knowledge about these compounds in plant immunity. Particular attention is paid to the intracellular localisation of the proteins/enzymes associated to polyamine metabolism, as well as the impact of pathogen effector proteins on the control of plant polyamine metabolism is discussed. [ABSTRACT FROM AUTHOR]

The role of the sesquiterpene botrydial in the interaction of the phytopathogenic fungus Botrytis cinerea and plant-associated bacteria was analyzed. From a collection of soil and phyllospheric bacteria, nine strains sensitive to growth-inhibition by B. cinerea were identified. B. cinerea mutants unable to produce botrydial caused no bacterial inhibition, thus demonstrating the inhibitory role of botrydial. A taxonomic analysis showed that these bacteria corresponded to different Bacillus species (six strains), Pseudomonas yamanorum (two strains) and Erwinia aphidicola (one strain). Inoculation of WT and botrydial non-producing mutants of B. cinerea along with B acillus amyloliquefaciens strain MEP 2 18 in soil demonstrated that both microorganisms exert reciprocal inhibitory effects; the inhibition caused by B. cinerea being dependent on botrydial production. Moreover, botrydial production was modulated by the presence of B. amyloliquefaciens MEP 2 18 in confrontation assays in vitro. Purified botrydial in turn, inhibited growth of Bacillus strains in vitro and cyclic lipopeptide (surfactin) production by B. amyloliquefaciens MEP 2 18. As a whole, results demonstrate that botrydial confers B. cinerea the ability to inhibit potential biocontrol bacteria of the genus Bacillus. We propose that resistance to botrydial could be used as an additional criterion for the selection of biocontrol agents of plant diseases caused by B. cinerea. Image 1 • The sesquiterpene botrydial produced by Botrytis cinerea inhibits bacteria associated to plants. • Botrydial lets B. cinerea antagonize Bacillus amyloliquefaciens in soil. • Botrydial lets B. cinerea resist the antagonistic effects of B. amyloliquefaciens. • Botrydial inhibits surfactin production by antagonistic B. amyloliquefaciens. • The ecological role of botrydial is wider than its phytotoxic effects on plant hosts of B. cinerea. [ABSTRACT FROM AUTHOR]

Abstract: A study on polyamine metabolism and the consequences of polyamine biosynthesis inhibition on the development of Sclerotinia sclerotiorum sclerotia was conducted. Concentrations of the triamine spermidine and the tetramine spermine, as well as ornithine decarboxylase and S-adenosyl-methionine decarboxylase activities, decreased during sclerotia maturation. In turn, the concentration of the diamine putrescine was reduced at early stages of sclerotial development but it increased later on. This increment was not related to de novo biosynthesis, as demonstrated by the continuous decrease in ornithine decarboxylase activity. Alternatively, it could be explained by the release of putrescine from the conjugated polyamine pool. α-Difluoro-methylornithine and cyclohexylamine, which inhibit putrescine and spermidine biosynthesis, respectively, decreased mycelial growth, but did not reduce the number of sclerotia produced in vitro even though they disrupted polyamine metabolism during sclerotial development. It can be concluded that sclerotial development is less dependent on polyamine biosynthesis than mycelial growth, and that the increase of free putrescine is a typical feature of sclerotial development. The relationship between polyamine metabolism and sclerotial development, as well as the potential of polyamine biosynthesis inhibition as a strategy for the control of plant diseases caused by sclerotial fungi are discussed. [Copyright &y& Elsevier]

Phosphorus (P), an essential macronutrient for all living organisms, is required in large amounts for the growth and development of plants. Although total soil P level is high, P bioavailability to plants is suboptimal in most soils because of high fixation rates into inorganic and organic insoluble complexes. Hence, plants are highly dependent on mechanisms that allow them to adapt to low‐phosphate stress and/or achieve suitable levels of soluble P on the root surface. In this regard, the rhizospheric microbiota plays a key role in facilitating P nutrition and has long been recognised for their potential use as an environmental‐friendly alternative to chemical P fertilisation. Herein, we outline the advances in the identification of phosphate solubilising bacteria and phosphate mineralising bacteria, collectively known as phosphobacteria, and their role in rendering P accessible to plants. We review and discuss research progress related to the introduction of phosphobacteria and/or P‐mineralising enzymes into soil, as well as plant transformation with bacterial genes that encode such enzymes, as strategies to improve plant growth and P nutrition. We also provide an overview of studies about the impact of variations in soil P levels on the structure of soil and rhizospheric microbial communities and the potential consequences of such perturbations on plant growth. Finally, we discuss possible directions for future research to optimise the efficiency of biofertilisation strategies based on the use of phosphobacteria. [ABSTRACT FROM AUTHOR]

Objective: This study is aimed to determine the association between the presence of Blastocystis sp. and gastrointestinal complaints in adults. Method: A descriptive study was carried out from January to December 2011 at the Centre of Hygiene, Epidemiology and Microbiology in Matanzas City, Cuba. A total of 749 adults (aged from 20 to 69 years old, mean age 38) had the opportunity to be included. Patients who had positive stool results for pathogenic bacteria, parasites and those with positive result to rotavirus were excluded from the study. A total of 240 adults were finally included, 128 (53.3%) male and 112 (46.67%) female with a mean age of 40 years old. To facilitate the comparison patients were divided into two groups: 110 adults with gastrointestinal complains and a second group of 130 adults without gastrointestinal disturbances. Sex distribution was homogenous in both groups. The fresh fecal samples were examined to determine the presence of Blastocystis sp. using the direct wet mount. Formalin-ether (Ritchie) technique was used to avoid the misdiagnosis of other intestinal parasites. In both techniques, the fresh samples were examined under light microscope. Results: Blastocystis sp. was detected in 49 patients (44.5%) in the symptomatic group and 28 (22.4%) in the asymptomatic one. Abdominal pain (52.7%) or distension (38.2%), acute diarrhea (26.4%), loss of appetite (18.2%), and dyspepsia (16.4%) were the gastrointestinal complains notified by patients included on the symptomatic group. The probability to identify Blastocystis sp. in patients with gastrointestinal complains was 2.9 times higher than in asymptomatic patients. Conclusion: Current results support those authors considering Blastocystis sp. as pathogen. [ABSTRACT FROM AUTHOR]

This work investigated the roles of the tetraamine thermospermine (TSpm) by analysing its contribution to Arabidopsis basal defence against the biotrophic bacterium Pseudomonas viridiflava. The participation of polyamine oxidases (PAOs) in TSpm homeostasis and TSpm-mediated defence was also investigated. Exogenous supply of TSpm, as well as ectopic expression of the TSpm biosynthetic gene ACL5, increased Arabidopsis Col-0 resistance to P. viridiflava, while null acl5 mutants were less resistant than Col-0 plants. The above-mentioned increase in resistance was blocked by the PAO inhibitor SL-11061, thus demonstrating the participation of TSpm oxidation. Analysis of PAO genes expression in transgenic 35S::ACL5 and Col-0 plants supplied with TSpm suggests that PAO 1, 3, and 5 are the main PAOs involved in TSpm catabolism. In summary, TSpm exhibited the potential to perform defensive functions previously reported for its structural isomer Spm, and the relevance of these findings is discussed in the context of ACL5 expression and TSpm concentration in planta. Moreover, this work demonstrates that manipulation of TSpm metabolism modifies plant resistance to pathogens. [ABSTRACT FROM AUTHOR]