Browsing by Author "Riquelme, Sebastian"

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    Condensed tannins from Pinus radiata bark: Extraction and their nanoparticles preparation in water by green method
    (2024) Cabrera-Barjas, Gustavo; Butto-Miranda, Nicole; Nesic, Aleksandra; Moncada-Basualto, Mauricio; Segura, Rodrigo; Bravo-Arrepol, Gaston; Escobar-Avello, Danilo; Moeini, Arash; Riquelme, Sebastian; Neira-Carrillo, Andronico
    This work reports for the first time the production of condensed tannin nanoparticles stable in water via modification with glycine betaine. Pine bark, as a byproduct from the paper industry, was used as a source of condensed tannins of high molecular weight. Different glycine betaine concentrations were tested to produce condensed tannin nanoparticles, and the obtained nanoparticles were subjected to several characterization techniques (Dynamic Light Scattering, Field emission scanning electron microscopy, Zeta potential, Fourier transform infrared spectroscopy-Attenuated total reflectance, thermogravimetric analysis). The results showed that the highest stability possessed nanoparticles with 40 wt% glycine betaine. The average particle size distribution evaluated by scanning microscopy was 124 nm. Besides, the glycine betaine-modified condensed tannin nanoparticles demonstrated higher thermal stability with the starting degradation temperature at 238 degrees C. Finally, obtained nanoparticles showed an antioxidant capacity of 34,209 +/- 2194 mu mol ET/100 g and low cytotoxicity towards healthy human cells, representing the high potential to be used as a carrier of active compounds in agriculture, food, drug and medical sector.
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    Constitutive and inducible defense in Eucalyptus determines the feeding host of Gonipterus platensis, denoting specific plant-insect coevolution and a strategy for resistance improvement
    (2022) Campos, Jasna V.; Riquelme, Sebastian; Pecio, Lukas; Guedes, Lubia; Mardones, Claudia; Alzamora, Rosa; Arteaga-Perez, Luis E.; Rubilar, Rafael; Fiehn, Oliver; Perez, Andy J.
    Defoliation caused by Gonipterus platensis on Eucalyptus seriously impacts tree growth rate and forest production. The weevil's feeding preference has sometimes limited which species of Eucalyptus to plant, although the plant's metabolic features that govern such choice still need to be uncovered. We used metabolomics to reveal the chemical traits mediating this interaction, focusing on a model formed by two Eucalyptus species with markedly different susceptibility, E. globulus (susceptible), and E. nitens (resistant). Our results suggest that the insect's feeding preference strongly depends on the Eucalyptus species' constitutive metabolome, especially on the stilbenes and hydrolysable tannins accumulation. The susceptible E. globulus could not produce such classes of metabolite either constitutively or after herbivory, which indicated an apparent lack of critical enzymes for biosynthesis of these substances, such as stilbene synthase (STS) and gallate 1-beta-glucosyltransferase. On the other hand, it seems that no matter how toxic the systemic defense induced in E. globulus after herbivory could be to an insect, counteradaptations, apparently evolved by the weevil, may efficiently detoxify them. This may result from plant-insect coevolution, given their common geographical origin. Inter-specific hybridizations between E. nitens and E. globulus have adapted hybrid species better to low temperatures and frost conditions, consequently being propagated for plantations in temperate regions. Thus, this research lays the groundwork for selecting the best parent genotypes and obtained hybrids, aiming to warrant the transfer of key resistance traits to progenies as an attractive strategy for future breeding programs.
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    Sirex noctilio infestation led to inevitable pine death despite activating pathways involved in tolerance
    (2022) Riquelme, Sebastian; Campos, Jasna, V; Pecio, Lukasz; Alzamora, Rosa; Mardones, Claudia; Simonet, Ana M.; Arteaga-Perez, Luis E.; Rubilar, Rafael; Fiehn, Oliver; Perez, Andy J.
    Defense-related metabolome traits in pine species after infestation by Sirex noctilio are largely unknown, despite, in most cases, trees being overwhelmed. Using LC-MS-based untargeted metabolomics, we revealed the systemic metabolic changes induced by this insect in 14-year-old Pinus radiata trees, the most affected species worldwide. An immediate metabolome alteration was expressed in needles after infestation, including the up-regulation of flavonols, flavan-3-ols, oxyneolignans, auxins, proline, and tryptophan, among others. The flavan-3-ols (catechin and procyanidin B1) suggested a rapidly induced photoprotection mechanism aided by diverting proline as an alternative substrate for respiration to compensate for the progressive chlorosis that degrades photosystems. Meanwhile, glutathione, glutamate, and ascorbate levels significantly dropped in needles, which may indicate the critical oxidative stress that trees had to face since the onset of the infestation. They were not fully replenished after long-term infestation, and redox homeostasis was probably not achieved, compromising tree survival. Nevertheless, a huge auxins overexpression detected in needles throughout the infestation may reflect tolerance against the premature senescence caused by the woodwasp venom. In contrast, the metabolome of wood tissues remained initially unchanged, although it seems to collapse after three months. Overall, the metabolomics strategy adopted in this work evidenced its usefulness in uncovering the fundamental roles of plants' chemical defense that govern interactions with specific stressors.