Crop pests and diseases lead to massive production loss, creating a global food supply and economic loss. Modern agriculture controls diseases by extensive application of chemicals, however this strategy brings undesired effects, such as human health problems by exposure to these chemicals, environmental contamination and development of pesticide resistant pathogens.
Agricultural industry is an economically important activity in Chile, compromising close to 10% of the labor force. The fruit industry (excluding table grapes) corresponds to 8.5% of the arable lands (342,654.2 hectares), where Prunus persica (peach and nectarines, called hereinafter as Peach) has an important place. Peach orchards are affected by several diseases such as, bacterial canker caused by the bacteria Pseudomonas syringae and brown rot blossom blight caused by the fungi Monilinia fructicola and M. laxa, which are controlled mainly by using pesticides. In this context, the need to better understand peach immunity has arisen for developing alternative or supplementary strategies to control crop diseases.
Plant immunity relies on the capacity of each individual cell to recognize pathogen threat, through cell surface and intracellular receptors, initiating immune responses to defend themselves. Cell surface receptors are called Pattern Recognition Receptors (PRRs) by their ability of recognizing characteristic microbial-derived molecules called microbe-associated molecular patterns (MAMPs). Upon MAMP recognition Pattern Triggered Immunity (PTI) is activated, defense responses are elicited enabling the plant to ward off pathogen colonization. MAMPs are distinctive molecules present in bacteria or fungi, non-strain specific, such as bacterial flagellin and fungal endoxylanases, which are recognized by specific PRRs, forming the MAMP/PRR recognition system that triggers the defense. The presence of PRRs is tightly correlated with higher broad pathogen resistance. In fact, transgenic Citrus sinensis, Medicago truncatula, Triticum avium, Nicotiana benthamiana, and Solanum lycopersicum carrying exogenous PRR present higher pathogen resistance. Moreover, Quantitative Trait Loci (QTL) linking resistance to pathogens with PRRs in Phaseolus vulgaris and Hordeum vulgare. These evidences highlight the potential of exploiting MAMP/PRR recognition system in modern agriculture.
We are focused to study in Peach two well described MAMP/PRR recognition model systems: flg22/FLS2 and xyn11/LeEIX2 recognition system. In the case of Flg22/FLS2 recognition system a conserved flagellin peptide, named flg22, is recognized by the PRR FLS2, activating oxidative burst, hormone production and transcriptional activation of Pathogen related (PR) genes. In xyn11/LeEIX2 recognition system a conserved peptide of endoxylanases type 11, named hereinafter xyn11, is recognized by the PRR EIX2, activating oxidative burst, ethylene production, expression of PR proteins and hypersensitive response. These recognition systems are agriculturally important because they can recognize the bacteria Bacillus sp, Pseudomonas sp and Xanthomonas sp and the fungi Trichoderma viridea and Botrytis cinerea. Remarkably, Bacterial Canker caused by Pseudomonas syringae is a current problem for Peach crops in Chile, as well, grey mold caused by Botrytis cinerea infection is a common post-harvesting disease for fruits.
Peach immunity is poorly described, however transcriptomic analysis showed more than 20 PRR like proteins induced by Xanthomonas arboricola infection and QTL analysis have identified two RLK genes associated to peach resistance against Monilinia spp, the causal agent of brown rot blossom blight, one of the most economically important peach diseases. However, no functional analyses have described MAMP/PRR recognition systems in peach to date. We expect to generate novel and valuable information regarding Peach immunity, characterizing peach flg22/FLS2 and xyn11/LeEIX2 recognition systems, as well as the defense responses triggered by them and their involvement in resistance to Pseudomonas syringae and Botrytis ciniera. In addition, we will explore whether these recognition systems, particularly xyn11/LeEIX2 participate in Monilinia spp recognition.

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.

Cumplo un rol de Investigador Asociado.

Which are the molecular and physiological mechanisms involved in priming and defense activation in cherry plants upon Pss infection?
Are these mechanisms differentially activated between susceptible and resistance cherry varieties?
Do susceptible and resistance cherry varieties present a differential priming under different PRIs exposure?

Even more, the increasing of aridity and drought in the North of the country, the advancing desert toward the South and a
reduction in water resources in the central zone of Chile, are expected along the XXI century. In this scenario of climate change, other question arises: Which are the molecular and physiological mechanisms involved in priming and defense activation in cherry plants upon Pss infection combined with water deficit?

Through this proposal, we intend to answer to these questions, in order to establish the basis for optimize the control of the bacterial canker in cherry fruit tree, by strategies that provide for the use of resistance inductors.
We propose two hypotheses: a) Cherry cultivars with differential susceptibility to bacterial canker, caused by Pseudomonas syringae pv. syringae, present genetic differences in the molecular machinery of plant immunity; b) Pseudomonas syringae pv. syringae infection is enhanced by water restriction due to an alteration of the molecular machinery of plant immunity.

The aims of this proposal is to obtain a better understanding of the plant-pathogen molecular interactions of sweet cherry bacterial canker in relationship with water deficit, using mainly omics strategies.

Con la apertura de la mina

El Teniente

en 1905, Chile
promovió la explotación a gran escala del cobre llamado “Gran
Minería del Cobre”. De ese momento a la fecha, se registran un
total de 757 relaves minero, dentro de los cuales un 85% de ellos
están abandonados o inactivos. Estos números posicionan a los
relaves como un problema importante, siendo actualmente el
pasivo ambiental de mayor impacto en nuestro país. En
particular, el relave Cauquenes ubicado en la Región de
O
Higgins, es el relave de cobre más antiguo y de mayor
dimensión, reservorio a la fecha del material depositado por El
Teniente. Considerando el número, tamaño y dimensiones,
sumado a la complejidad del escenario ambiental y las variables
involucradas, el estudio de las comunidades microbianas que
habitan los relaves mineros debe abordarse desde diferentes
disciplinas. Por estos motivos, a través de la interconexión de las
diversas capacidades de investigadores nacionales e
internacionales, el presente proyecto busca sentar las bases para
la creación de un Centro de Biología de Sistemas para el estudio
de comunidades que habitan relaves mineros. A nivel de
investigación. el Centro se enfocará en: i) Caracterizar la
estructura de las comunidades extremófilas de los relaves. ii)
Identificar y validar de los potenciales metabólicos de las
comunidades y sus miembros. iii) Generar un registro y
clasificación de información – Bases de datos y colección de
cepas. iv) Desarrollo de biotecnología para aplicaciones en
minería. En definitiva, con un fuerte compromiso regional, el
proyecto contempla abordar por primera vez desde una
perspectiva multidisciplinaria e integral, el estudio de
comunidades de especies extremófilas presentes en el relave
Cauquenes, sentando las bases para que el Centro de Biología de
Sistemas pueda en el corto plazo, proyectarse como un espacio
real para al estudio de microorganismos que habitan los relaves
en Chile.

AbstractPlant immunity is often defined by the “immunity hormones”: salicylic acid (SA), jasmonic acid (JA), and ethylene (ET). These hormones are well known for differentially regulating defense responses against pathogens. In recent years, the involvement of other plant growth hormones such as auxin, gibberellic acid, abscisic acid, and cytokinins (CKs) in biotic stresses has been recognized. Previous reports have indicated that endogenous and exogenous CK treatment can result in pathogen resistance. We show here that CK induces systemic tomato immunity, modulating cellular trafficking of the PRR LeEIX2 and promoting biotrophic and necrotrophic pathogen resistance in an SA and ET dependent mechanism. CK perception within the host underlies its protective effect. Our results support the notion that CK acts as a priming agent, promoting pathogen resistance by inducing immunity in the host.