Publications by authors named "Sebastiano Nigris"

4 Publications

  • Page 1 of 1

Biocontrol traits of Bacillus licheniformis GL174, a culturable endophyte of Vitis vinifera cv. Glera.

BMC Microbiol 2018 10 16;18(1):133. Epub 2018 Oct 16.

Botanical Garden and Department of Biology, University of Padova, Padova, Italy.

Background: Bacillus licheniformis GL174 is a culturable endophytic strain isolated from Vitis vinifera cultivar Glera, the grapevine mainly cultivated for the Prosecco wine production. This strain was previously demonstrated to possess some specific plant growth promoting traits but its endophytic attitude and its role in biocontrol was only partially explored. In this study, the potential biocontrol action of the strain was investigated in vitro and in vivo and, by genome sequence analyses, putative functions involved in biocontrol and plant-bacteria interaction were assessed.

Results: Firstly, to confirm the endophytic behavior of the strain, its ability to colonize grapevine tissues was demonstrated and its biocontrol properties were analyzed. Antagonism test results showed that the strain could reduce and inhibit the mycelium growth of diverse plant pathogens in vitro and in vivo. The strain was demonstrated to produce different molecules of the lipopeptide class; moreover, its genome was sequenced, and analysis of the sequences revealed the presence of many protein-coding genes involved in the biocontrol process, such as transporters, plant-cell lytic enzymes, siderophores and other secondary metabolites.

Conclusions: This step-by-step analysis shows that Bacillus licheniformis GL174 may be a good biocontrol agent candidate, and describes some distinguished traits and possible key elements involved in this process. The use of this strain could potentially help grapevine plants to cope with pathogen attacks and reduce the amount of chemicals used in the vineyard.
View Article and Find Full Text PDF

Download full-text PDF

Source Listing
October 2018

The Hydrophobin HYTLO1 Secreted by the Biocontrol Fungus Triggers a NAADP-Mediated Calcium Signalling Pathway in .

Int J Mol Sci 2018 Sep 1;19(9). Epub 2018 Sep 1.

Department of Biology, University of Padova, Via U. Bassi 58/B, 35131 Padova, Italy.

filamentous fungi are increasingly used as biocontrol agents and plant biostimulants. Growing evidence indicates that part of the beneficial effects is mediated by the activity of fungal metabolites on the plant host. We have investigated the mechanism of plant perception of HYTLO1, a hydrophobin abundantly secreted by , which may play an important role in the early stages of the plant-fungus interaction. Aequorin-expressing suspension cell cultures responded to HYTLO1 with a rapid cytosolic Ca increase that dissipated within 30 min, followed by the activation of the defence-related genes , , and . The Ca-dependence of these gene expression was demonstrated by using the extracellular Ca chelator EGTA and Ned-19, a potent inhibitor of the nicotinic acid adenine dinucleotide phosphate (NAADP) receptor in animal cells, which effectively blocked the HYTLO1-induced Ca elevation. Immunocytochemical analyses showed the localization of the fungal hydrophobin at the plant cell surface, where it forms a protein film covering the plant cell wall. Our data demonstrate the Ca-mediated perception by plant cells of a key metabolite secreted by a biocontrol fungus, and provide the first evidence of the involvement of NAADP-gated Ca release in a signalling pathway triggered by a biotic stimulus.
View Article and Find Full Text PDF

Download full-text PDF

Source Listing
September 2018

Characterization of lipopeptides produced by Bacillus licheniformis using liquid chromatography with accurate tandem mass spectrometry.

Rapid Commun Mass Spectrom 2016 Oct;30(20):2237-52

Department of Biology, University of Padova, via Ugo Bassi 58/B, 35131, Padova, Italy.

Rationale: The plant endophyte Bacillus licheniformis, isolated from leaves of Vitis vinifera, was studied to individuate and characterize the presence of bioactive lipopeptides having amino acidic structures.

Methods: Crude extracts of liquid cultures were analyzed by ultra-high-performance liquid chromatography (UHPLC) coupled to a quadrupole time-of-flight (QTOF) mass analyzer. Chromatographic conditions were optimized in order to obtain an efficient separation of the different isobaric lipopeptides, avoiding merged fragmentations of co-eluted isomeric compounds and reducing possible cross-talk phenomena. Composition of the amino acids was outlined through the interpretation of the fragmentation behavior in tandem high-resolution mass spectrometry (HRMS/MS) mode, which showed both common-class and peculiar fragment ions. Both [M + H](+) and [M + Na](+) precursor ions were fragmented in order to differentiate some isobaric amino acids, i.e. Leu/Ile. Neutral losses characteristic of the iso acyl chain were also evidenced.

Results: More than 90 compounds belonging to the classes of surfactins and lichenysins, known as biosurfactant molecules, were detected. Sequential LC/HRMS/MS analysis was used to identify linear and cyclic lipopeptides, and to single out the presence of a large number of isomers not previously reported. Some critical issues related to the simultaneous selection of different compounds by the quadrupole filter were highlighted and partially solved, leading to tentative assignments of several structures. Linear lichenysins are described here for the first time.

Conclusions: The approach was proved to be useful for the characterization of non-target lipopeptides, and proposes a rationale MS experimental scheme aimed to investigate the difference in amino acid sequence and/or in the acyl chain of the various congeners, when standards are not available. Results expanded the knowledge about production of linear and cyclic bioactive compounds from Bacillus licheniformis, clarifying the structures of isomeric forms, and enabling the use of selected endophytes to produce fungicides for eco-friendly biocontrol. Copyright © 2016 John Wiley & Sons, Ltd.
View Article and Find Full Text PDF

Download full-text PDF

Source Listing
October 2016

Beneficial Bacteria Isolated from Grapevine Inner Tissues Shape Arabidopsis thaliana Roots.

PLoS One 2015 16;10(10):e0140252. Epub 2015 Oct 16.

Dipartimento di Biologia, Universita degli Studi di Padova, Padova, Italy.

We investigated the potential plant growth-promoting traits of 377 culturable endophytic bacteria, isolated from Vitis vinifera cv. Glera, as good biofertilizer candidates in vineyard management. Endophyte ability in promoting plant growth was assessed in vitro by testing ammonia production, phosphate solubilization, indole-3-acetic acid (IAA) and IAA-like molecule biosynthesis, siderophore and lytic enzyme secretion. Many of the isolates were able to mobilize phosphate (33%), release ammonium (39%), secrete siderophores (38%) and a limited part of them synthetized IAA and IAA-like molecules (5%). Effects of each of the 377 grapevine beneficial bacteria on Arabidopsis thaliana root development were also analyzed to discern plant growth-promoting abilities (PGP) of the different strains, that often exhibit more than one PGP trait. A supervised model-based clustering analysis highlighted six different classes of PGP effects on root architecture. A. thaliana DR5::GUS plantlets, inoculated with IAA-producing endophytes, resulted in altered root growth and enhanced auxin response. Overall, the results indicate that the Glera PGP endospheric culturable microbiome could contribute, by structural root changes, to obtain water and nutrients increasing plant adaptation and survival. From the complete cultivable collection, twelve promising endophytes mainly belonging to the Bacillus but also to Micrococcus and Pantoea genera, were selected for further investigations in the grapevine host plants towards future application in sustainable management of vineyards.
View Article and Find Full Text PDF

Download full-text PDF

June 2016