Proyectos

Drought events, worsened by the effects of climate change, have led to the search of alternative agricultural drought tolerant species with high economical value. Almond (Prunus dulcis) it’s a suitable alternative to central Chile because it has been extensively characterized as drought tolerant. Despite that the effects of drought on plant physiology and growth, such as stomatal closure, are well known, species and cultivars have developed a range of responses to cope with water shortage. In this regard, the iso- and anisohydric behaviors have been extensively researched in species with economic value such as grapevines. While isohydric species are characterized by fast stomatal closure under drought to avoid a decrease in leaf water potential (Ψleaf), anisohydric species can maintain stomata open for longer allowing carbon assimilation and increasing water use efficiency (WUE) and growth. This has led to the search of cultivars or genotypes with anisohydric behavior. In this regard, according to recent research, a proper characterization of plant-water relations measurements during soil desiccation (SD) can allow the quantification of (an)isohydric behavior among cultivars. Although previous research have pointed towards a possible differences in (an)isohydric behavior in almond, and our preliminary research has showed different hydroscape areas of two distinct almond varieties, indicative of contrasting (an)isohydric behavior, there is need for an intensive assessment of plant-water relations changes during SD, to identify cultivars that are capable of maintaining stomata open during SD, favoring carbon assimilation, WUE and growth. In this regard, abscisic acid (ABA) metabolism has been linked to different stomatal responses during drought. While the role of ABA as the single root-to-shoot signal during drought has been disproved, there is no doubt that this hormone plays a central role in stomatal behavior. Accordingly, other mechanisms have been proposed as part of the signaling pathway from roots to shoots during drought. Among them, inactive ABA conjugated with glucose ester (ABA-GE) can be rapidly converted to active free ABA, serving as a quick source of ABA in comparison with de novo synthesis. According to Arabidopsis studies, this increase in ABA either from de novo synthesis of from ABA-GE is triggered by the peptide CLE25, which is proposed as the main root-to-shoot signal during drought. Although this peptide has not been researched in other species, it is present in the Prunus genome indicating that can also be involved in drought responses in almond, and consequently has a possible contribution with differential responses among (an)isohydric cultivars. These new players within the signaling pathway from roots to shoots during drought have led to a new proposed model for ABA signaling during drought. Thus, low water availability decrease root hydraulic conductivity triggering the synthesis of CLE25 as the main root-to-shoot signal that elicit synthesis in ABA either from de novo synthesis or by release from ABA-GE, this in turn decreases leaf hydraulic conductivity causing stomatal closure. Although changes in ABA concentration have been related to the (an)isohydric behavior, research regarding CLE25 peptide has not been developed yet in economically important woody species. According to the later, the following research question is proposed: Is the synthesis of CLE25 peptide and ABA concentrations correlated with the (an)isohydric behavior in almond cultivars?. To answer this question the following hypothesis is presented: “During soil desiccation, an increase in CLE25 peptide and ABA concentration and a decrease in root hydraulic conductivity occurs previously in isohydric than in anisohydric almond cultivars. Which in turn, is correlated with a maintenance in leaf water potential and increase in stomatal closure”. To prove this hypothesis, three specific goals are proposed (1) To screen for different (an)isohydric behaviors between different P. dulcis cultivars according Ψleaf and gs evolution during soil desiccation (SD), (2) Test the differences in morphology, WUE and growth between contrasting isohydric and anisohydric cultivars of almond. (3) Evaluate the relationship between CLE25 peptide with ABA metabolism and hydraulic conductivity in almond cultivars with contrasting an(isohydric) behavior during SD. These objectives will be met by exhaustive characterization of plant-water relations and physiological parameters of different almond cultivars during progressive SD. Then, quantification of CLE25 peptide, free and conjugated ABA and gene expression will be measured in roots and leaves of accessions with different (an)isohydric behavior during SD. Changes in CLE25 and ABA will be correlated with plat-water relation and physiological parameters that determine the (an)isohydric behavior. As observed in our preliminary results we expect to observe contrasting hydroscapes areas and stomatal control of selected almond cultivars. Then, anisohydric accessions will be characterized by increased growth and lower WUE due to higher photosynthesis and gs. Finally, isohydric accessions will display a rapid increase in CLE25 and free ABA and a decrease in ABA-GE concentrations, and corresponding gene expression, with the progression of SD. While anisohydric accession will display a slower response in CLE25 and ABA metabolism in agreement with lower stomatal control during SD, thus accepting our hypothesis.

Forest dynamics have been affected by the high rates of greenhouse gas emissions that have direct consequences on global warming. This phenomenon is evident with the intensification of mega drought events in various parts of the world, including Chilean forests. It is still unclear how climate change may affect tree and shrub growth, especially in altitude regions such as the Mediterranean Andes of Central Chile (MACC) and how these populations would react to drought events on a timescale. In this sense, tree rings is one of the most important proxies for reconstructing environmental data, as trees contain historical records of previous growth conditions at annual resolution, which seems a useful tool to know the variations in xylem traits of woody species over time. One of the most important advances in tree-ring studies has been the additional focus on anatomical (i.e. vessels and wood density) and ecophysiological (i.e. carbon stable isotopes) features, since shows tree sensitivity to intra-seasonal environmental factors. The present proposal seek to investigate the adaptive strategies of woody species, based on xylem functional traits, for survival in current climate change scenarios on latitudinal and altitudinal gradients of the MACC, complementing dendrochronological, anatomical and isotopic analysis. This allow us to order to define priority locations for conservation and restoration projects and to identify which regions and populations are most vulnerable or resistant to severe climate change. We will test four hypotheses: (i) woody species populations from xeric sites have developed throughout their evolutionary history a hydraulic structure oriented to safety in comparison with the populations of wet sites; (ii) populations of all sites will have an increase of water use efficiency (iWUE) over time, as a result of a climate change adaptability strategy of trees, but it will not necessarily be reflected in higher trunk biomass; and (iii) xylem traits varied by altitudinal gradient affecting tree growth, being the populations of tree lines those that have trait values more resistant to current climatic change, and hence, more adapted to future scenarios of climate change. To test those hypotheses, we will select and will sample trees and shrub population of MACC (30-35°S, 71-71.5°W). We will use bibliography, expert interviews and local communities to select potential sites, as well as a drone (Phantom 4RTK®) to analyze vegetation characteristics. Preliminarily, the genera Prosopis, Acacia, Berberis and Adesmia will be selected because present wide distribution in MACC and high dendrochronological potential. Thus, this project will show us how they will respond in the future under the current climatic trends, identifying which regions and populations are the most vulnerable to climate change in the Andes of central Chile. Likewise, these results will serve to measure how the impacts of environmental variations have been in a region with high levels of endemism in South America, both in structure, hydraulic plasticity and carbon storage, being useful to be in conservation and restoration project, as well as replicated in future studies of other areas, both in South America and the world.

Existen dos tipos de restauración ecológica: activa y pasiva. La primera se refiere a la recuperación artificial del sistema, mediante un programa de introducción y manejo de especies simulando la sucesión natural. Este tipo de restauración es muy conveniente en aquellas áreas donde el ecosistema no es capaz de recuperarse naturalmente y se requiere la intervención del hombre, que a priori, no sería el caso del SNLN. Mientras que la Restauración pasiva se refiere a la recuperación natural del sistema, sin intervención o con un manejo mínimo. Este tipo de restauración se recomienda cuando no hay medios económicos o hay dificultades logísticas para recuperar áreas que son relativamente grandes, como es el caso del SNLN. El principio básico de este tipo de restauración es dejar que el sistema siga su curso natural de recolonización de especies nativas, dándole un mínimo impulso. Por lo tanto, actividades de restauración pasiva, como el cercado, pueden tener un efecto positivo sobre las condiciones de sitio y micrositio. El cercado reduce la presión de agentes de degradación como el ganado mayor, lo que favorece la regeneración, el aumento de la cobertura vegetal y la fijación de nutrientes en el suelo.

La Universidad de O’Higgins postula la incorporación como académico a la Dra. Lorena Pizarro al Instituto de Ciencias Agronómicas y Veterinarias. La Dra Pizarro es una investigadora joven, de excelencia académica, productiva y de alta competitividad, quien cumple a cabalidad con la misión de nuestra Universidad en la generación y difusión de conocimiento, para el desarrollo la Región de O’Higgins y el país. Ella es especialista en inmunidad vegetal desempeñándose actualmente como investigador post-doctoral en Israel, en los laboratorios del Dr Adi Avni (Tel-Aviv University) y la Dra Maya Bar (Volcani Center). La candidata propone el estudio de la respuesta inmune de especies de frutales del género Prunus, tales como Cerezo, Durazno y nectarines, los cuales son de gran importancia en la producción agrícola de la región de O’Higgins y el país. Particularmente, esta propuesta de investigación plantea el estudio de una novedosa y versátil estrategia para la activación de la inmunidad en frutales del género Prunus, a través de la aplicación de elicitores de origen bacteriano y fúngico. De esta forma, se espera potenciar la tolerancia a patógenos en estos frutales, y mejorar los sistemas de control de plagas usados en Chile. Se proyecta que la Dra Pizarro desarrolle esta nueva línea de investigación basada en las necesidades agrícolas de la región, fortalezca la masa crítica de la fitopatología frutícola en nuestra institución, participe de manera transversal en el distintos institutos, mantenga una estrecha colaboración con la región a través de comunicación directa con el sector agrícola y Escuelas de la región a través de nuestro programa PAR-Explora, establezca colaboraciones nacionales e internacionales, y se adjudique de proyectos de investigación extramurales, para así ser parte del desarrollo y posicionamiento a la Universidad de O’Higgins como una institución de educación superior de reconocida calidad a nivel regional, nacional e internacional.

Proyecto FIOUCH 2019 S-19-16