Publications by authors named "Katia R Prieto"

4 Publications

  • Page 1 of 1

, an Endophyte That Establishes a Nutrient-Transfer Symbiosis With Banana Plants and Protects Against the Black Sigatoka Pathogen.

Front Microbiol 2019 7;10:804. Epub 2019 May 7.

Department of Chemistry, Universidad Autónoma de Guadalajara, Zapopan, Mexico.

Banana ( spp.) is an important crop worldwide, but black Sigatoka disease caused by the fungus threatens fruit production. In this work, we examined the potential of the endophytes of banana plants and , as antagonists of and support plant growth in nutrient limited soils by N-transfer. The two bacterial isolates were identified by MALDI-TOF mass spectrometry and corroborated by 16S rRNA sequence analysis. Both bacteria were positive for beneficial traits such as N-fixation, indole acetic acid production, phosphate solubilization, negative for 1-aminocyclopropane 1-carboxylic acid deaminase and were antagonistic to . To measure the effects on plant growth, the two plant bacteria and an strain (as non-endophyte), were inoculated weekly for 60 days as active cells (AC) and heat-killed cells (HKC) into plant microcosms without nutrients and compared to a water only treatment, and a mineral nutrients solution (MMN) treatment. Bacterial treatments increased growth parameters and prevented accelerated senescence, which was observed for water and mineral nutrients solution (MMN) treatments used as controls. Plants died after the first 20 days of being irrigated with water; irrigation with MMN enabled plants to develop some new leaves, but plants lost weight (-30%) during the same period. Plants treated with bacteria showed good growth, but AC treated plants had significantly greater biomass than the HKC. After 60 days, plants inoculated with AC showed intracellular bacteria within root cells, suggesting that a stable symbiosis was established. To evaluate the transference of organic N from bacteria into the plants, the 3 bacteria were grown with NHCl or NaNO as the nitrogen source. The N transferred from bacteria to plant tissues was measured by pheophytin isotopomer abundance. The relative abundance of the isotopomers 872.57, 873.57, 874.57, 875.57, 876.57 unequivocally demonstrated that plants acquired N atoms directly from bacterial cells, using them as a source of N, to support plant growth in restricted nutrient soils. might be a new alternative to promote growth and health of banana crops.
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http://dx.doi.org/10.3389/fmicb.2019.00804DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6513882PMC
May 2019

In-vivo electrochemical monitoring of HO production induced by root-inoculated endophytic bacteria in Agave tequilana leaves.

Biosens Bioelectron 2018 Jan 18;99:108-114. Epub 2017 Jul 18.

Department of Fundamental Chemistry, Institute of Chemistry, University of São Paulo, Av. Prof. Lineu Prestes, 748, 05508-000 São Paulo, SP, Brazil. Electronic address:

A dual-function platinum disc microelectrode sensor was used for in-situ monitoring of HO produced in A. tequilana leaves after inoculation of their endophytic bacteria (Enterobacter cloacae). Voltammetric experiments were carried out from 0.0 to -1.0V, a potential range where HO is electrochemically reduced. A needle was used to create a small cavity in the upper epidermis of A. tequilana leaves, where the fabricated electrochemical sensor was inserted by using a manual three-dimensional micropositioner. Control experiments were performed with untreated plants and the obtained electrochemical results clearly proved the formation of HO in the leaves of plants 3h after the E. cloacae inoculation, according to a mechanism involving endogenous signaling pathways. In order to compare the sensitivity of the microelectrode sensor, the presence of HO was detected in the root hairs by 3,3-diaminobenzidine (DAB) stain 72h after bacterial inoculation. In-situ pH measurements were also carried out with a gold disc microelectrode modified with a film of iridium oxide and lower pH values were found in A. tequilana leaves treated with bacteria, which may indicate the plant produces acidic substances by biosynthesis of secondary metabolites. This microsensor could be an advantageous tool for further studies on the understanding of the mechanism of HO production during the plant-endophyte interaction.
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http://dx.doi.org/10.1016/j.bios.2017.07.039DOI Listing
January 2018

Nitrogen acquisition in Agave tequilana from degradation of endophytic bacteria.

Sci Rep 2014 Nov 6;4:6938. Epub 2014 Nov 6.

Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, 05508-000, São Paulo, SP, Brazil.

Plants form symbiotic associations with endophytic bacteria within tissues of leaves, stems, and roots. It is unclear whether or how plants obtain nitrogen from these endophytic bacteria. Here we present evidence showing nitrogen flow from endophytic bacteria to plants in a process that appears to involve oxidative degradation of bacteria. In our experiments we employed Agave tequilana and its seed-transmitted endophyte Bacillus tequilensis to elucidate organic nitrogen transfer from (15)N-labeled bacteria to plants. Bacillus tequilensis cells grown in a minimal medium with (15)NH4Cl as the nitrogen source were watered onto plants growing in sand. We traced incorporation of (15)N into tryptophan, deoxynucleosides and pheophytin derived from chlorophyll a. Probes for hydrogen peroxide show its presence during degradation of bacteria in plant tissues, supporting involvement of reactive oxygen in the degradation process. In another experiment to assess nitrogen absorbed as a result of endophytic colonization of plants we demonstrated that endophytic bacteria potentially transfer more nitrogen to plants and stimulate greater biomass in plants than heat-killed bacteria that do not colonize plants but instead degrade in the soil. Findings presented here support the hypothesis that some plants under nutrient limitation may degrade and obtain nitrogen from endophytic microbes.
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http://dx.doi.org/10.1038/srep06938DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4221784PMC
November 2014

The photophysical determination of the minimum hydrotrope concentration of aromatic hydrotropes.

J Colloid Interface Sci 2007 Nov 17;315(2):810-3. Epub 2007 Jul 17.

Instituto de Química de São Carlos, Universidade de São Paulo, Caixa Postal 780, 13560-970 São Carlos SP, Brazil.

A method based on the aggregate to monomol emission ratio, I(aggr)/I(monomol), was used to determine the minimal hydrotropic concentration (MHC) of aromatic hydrotropes. The main advantage of this method is that it does not require the use of probes or other additives, which might disrupt the aggregation process. Also, it relies on spectrophotometric measurements, which are more sensitive and less arduous than others, like conductivity, light scattering and surface tension.
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http://dx.doi.org/10.1016/j.jcis.2007.07.020DOI Listing
November 2007