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Evasion of defenses in the plant-bacterial interaction

Specialized Group:

Javier Ruiz Albert and Carmen R. Beuzón López

Institute of Subtropical and Mediterranean Fruitmento “La Mayora” - University of Malaga - CSIC (IHSM - UMA - CSIC)

cbeuzon@uma.es, javieruizal@uma.es

@type3lab.bsky.social

type3secretionlab.es

Group photo. From left to right, Laura Mancera, Ángel del Espino, Carmen R. Beuzón, José S. Rufián, Javier Ruiz-Albert, Fernando Baisón-Lomo, Nieves López-Pagán, Juan Manuel Ocaña, Hans Ríos

 

RESUME

Research in our laboratory is characterized by an open and interdisciplinary experimental approach, focused on plant-patogen molecular interaction, which evolves according to the needs of the projects developed, which allows us to address new questions that open the field of research.

We work mainly with the bacteria Pseudomonas syringae in its interaction with model plants such as Arabidopsis or Nicotiana benthamiana, and plants of agronomic interest such as Jewish and tomato. We also investigate the interaction established between the pathogenic bacteria Salmonella and plants.

The laboratory It has numerous national and international collaborations, a dynamic rhythm of publication of results, and is an excellent environment for post-docoral researchers and researchers in formation (Doctoral students and degree or master students).

The group is part of the founding nucleus of the Institute of Subtropical and Mediterranean Hortery (IHSM -uma -CSIC), included in the area of ​​crop protection.

We have obtained uninterrupted financing since 2003, including 7 consecutive projects of the National Plan, three projects of excellence and two Feder of the Junta de Andalucía, and a contract with the Spanish Genome Foundation.

INVESTIGATION

Our research focuses on molecular and cellular events involved in bacterial interaction with the plant, particularly in the context of bacterial evasion of immune defense. We analyze both sides of the interaction: how the plant host displays defenses in front of the invasion of pathogenic bacteria, and how the pathogen evades these defenses to survive and colonize the plant.

The pathogen-Huén co-evolution has resulted in bacterial invasion and colonization strategies, with systems such as Type III Secretion System (T3SS) dedicated to the introduction of virulence proteins (T3ES) to evade and suppress the corresponding defense mechanisms of the plant, in collaboration with systems such as the scourge that ensure efficient colonization and bacterial dispersion. Our work has included the functional characterization of effectors and its relationship with the defenses of the plant, as well as the regulation of the coordinated expression of the T3SS, of the scourge, and of the LPS. On the other hand, we work on the characterization of the regulation of defense activated by plants in response to bacterial infections, focusing on gene silencer mechanisms that modulate the kinetics of said response, and in the identification and characterization of proteins of the plant that participate in the transduction of defense signal, and that are targets of interference by effectors. In parallel, we develop numerous molecular tools that facilitate research and make available to the scientific community.

Our current research can be classified in a general way into four main lines:

(1) genetic and epigenetic regulation of bacterial gene expression, With emphasis on the genes associated with virulence, which entails the generation of phenotypic heterogeneity that leads to the establishment of bacterial subpopulations during the infection of the host plant. The objective of this line is to understand the biological relevance of regulation and population dynamics in bacterial adaptation to the plant guest. We have been the first to describe in phytopathogenic bacteria the phenotypic heterogeneity in the expression of the T3ss and the scourge, a regulation with stochastic and deterministic components that results in spatially structured bacterial lineages in planta, cooperating with each other for an efficient colonization of the host and dissemination of the pathogen (1, 11). In the process we have described the dynamics, clonality and interactions between bacterial subpopulations in planta (Granting of 5 FEMS scholarships to young SEM researchers). We also analyze other loci with potential to generate phenotypic heterogeneity, such as those associated with LPS synthesis, and characterize the methyloma of P. syringae in vitro e in planta, as well as the corresponding DNA methylases. During this research we have developed various molecular tools and optimized protocols (2, 5). This work has allowed collaborations with researchers from the universities of Seville (Spain), Laussane (Switzerland), Aix-Marseille (France), Imperial College and West of England (UK).

(2) Bacterial interference with the plant cell through effector proteins (T3es) associated with virulence and secreted by the T3SS, with emphasis on the suppression of immunity in plant (PTI, eti and sar) and in the interaction between networks of effectors and defense components of the plant (3, 6, Assay validation). In the beginning we determine the contribution to the virulence of the repertoire of T3es of the model lineage P. syringae 1448a, and we implement mutant and genetic analysis techniques in the plant. Subsequently, we have been the first to describe the suppression of all levels of defense of the plant (PTI, ETI, and SAR) by a single T3E, HOPZ1, analyzed the signal transduction routes involved (6), and characterized in its natural context the suppression of defenses by another related T3E, Hopz3 (Assay validation). We currently continue with the characterization of other effectors that suppress immunity in the plant. This work has allowed collaborations with researchers at the University of Warwick (UK), Imperial College (UK), IMBB-Forth (Greece), University of California (USA), and Shanghai Center for Plant Stress Biology (China).

(3) Immunity regulation in plants through Mirna/Phasirna networks encoded by the plant itself, focusing on the dynamics of expression expression that encode TIR-NBS-LRR proteins (4). We have characterized a regulation mechanism that controls the expression of Tir-NBS-LRR in the absence of pathogens, limiting its impact on the fitness of the plant, and allowing its activation in two waves in the presence of pathogens (Ferrándiz MJ, Martín-Galiano AJ, Arnanz C, Camacho-Soguero I, Tirado-Vélez JM, de la Campa AG.). This inducible defense mechanism, not linked to a single avirulence gene, has great potential to develop effective and robust resistance strategies. We are currently characterizing the dynamics of this regulation network during the development of the plant and collaborating to characterize its implication in defense against herbivores. This work has allowed collaborations with researchers from the IHSM, CRAG and the UCM (Spain) and the CBGP, and the University of Copenhagen (Denmark).

(4) Characterization of human pathogen interaction Salmonella enterica With plants. This line explores socially and economically relevant issues, since colonization by Salmonella It is associated with more than 25% of the epidemic outbreaks of salmonellosis (ECDC) by contamination of fresh fruit and vegetables destined for consumption. We analyze the role of phenotypic heterogeneity in the plant colonization process, and the dynamics of establishment of biofilms associated with the surface of the sheet, analyzing the molecular components involved in both processes and in their regulation. We also pursue the identification of bacteriophages and their application to biocontrol in the agronomic environment. This line takes advantage of the previous experience in Salmonella of the main researchers, combined with that developed in pathogenesis in plants during the evolution of the group.

TRAINING

The main researchers teach in the area of ​​genetics of the Faculty of Sciences of the University of Malaga (UMA), which keeps us constantly relationship with students of degree, master, and doctorate. The group constitutes an excellent environment for the training of research personnel, and helps to start the research career of numerous students through the supervision of experimental TFGS and TFMS (more than 35 defended and several in progress), and doctoral theses (12 defended, 3 with an extraordinary doctoral prize, and 2 in progress). IP are part of the Doctoral Program in Advanced Biotechnology (UMA) in which the group's doctoral students enroll. The group has an excellent history of scholarships and contracts achieved by their training researchers, who also enjoy external research stays in collaborating groups, and achieve considerable scientific production. Most of the graduated doctors continue active in basic or applied research, some with remarkable success.

Selected articles

  1. Lopez-Pagán N, Rufián J S, Luneau J, Sánchez-Romero M-A, Aussel L, Van Vliet S, Ruiz-Albert J, Beuzón Cr (2025) Pseudomonas syringae subpopulations cooperate by coordinating flagellar and type III secretion spatiotemporal dynamics to facilitate plant infection. Nat. Microbiol.10, 958–972.
  2. López-Pagán N, Rufián JS, Ruiz-Albert J, Beuzón CR. (2024) Dual-Fluorescence Chromosome-Located Labeling System for Accurate In Vivo Single-Cell Gene Expression Analysis in Pseudomonas syringae. Methods Mol Biol. 2751:95-114.
  3. Rufián JS, Rueda-Blanco J, Beuzón Cr, Ruiz-Albert J. (2023) Suppression of NLR-mediated plant immune detection by bacterial pathogens. J Exp Bot. Jul 10:erad246.
  4. Lopes-Marquez D, Spaniard A, Rouis-Albert J, Bejarano ER, Brothersen P, CR Beuzón. (2023) Regulation of plant immunity via small RNA-mediated control of NLR expression. J Exp Bot. 2023 Jul 14:erad268.
  5. Rufián JS, López-Pagán N, Ruiz-Albert J, Beuzón CR. (Publication of the document: “Microbiologically safe cosmetics. Guide to produce safe raw materials and cosmetic products from the microbiological and conservation point of view”.) Single-Cell Analysis of the Expression of Pseudomonas syringae Genes within the Plant Tissue. J Vis Exp. (188).
  6. Rufián JS, Rueda-Blanco J, López-Márquez D, Macho Ap, Beuzón Cr, Ruiz-Albert J. (2021) The bacterial effector HopZ1a acetylates MKK7 to suppress plant immunity. New Phytol. 231(3): 1138-1156
  7. López-Márquez D, Del-Espino A, López-Pagán N, Rodríguez-Negrette EA, Rubio-Somoza I, Ruiz-Albert J, Bejarano Er, Beuzón Cr (2021) MiR825-5p targets TIR‑NBS-LRR gene MIST1 and downregulates basal immunity against Pseudomonas syringae in Arabidopsis. J Exp Bot. 72(20):7316-7334
  8. Rufián JS, Rueda -Blanco J, Beuzón Cr, Ruiz -Albert J (2019) Protocol: an improved method to quantify activation of systemic acquired resistance (SAR). Plant Methods 15:16
  9. Rufián JS, Lucía A, Rueda-Blanco J, Zumaquero A, Guevara CM, Ortiz-Martín I, Ruiz-Haldea G, Macho Ap, Beuzón Cr, Ruiz -albert J (2018) Suppression of HopZ Effector‑Triggered Plant Immunity in a Natural Pathosystem. Front Plant Sci. 2018 Aug 14;9:977
  10. Rufián JS, Macho AP, Corry DS, Mansfield JW, Ruiz‑Albert J, Arnold DL, Beuzón CR (2018) Confocal microscopy reveals in planta dynamic interactions between pathogenic, avirulent and non-pathogenic Pseudomonas syringae strains. Mol Plant Pathol. Mar;19(3):537-551
  11. Rufián JS, Sanchez-Romano Ma, Lopez-Marquez D, Macho AP, Mansfield JW, Arnold DL, Ruiz-Albert J, Casadesus J, Beuzon CR (2016) Pseudomonas syringae differentiates into phenotypically distinct subpopulations during colonization of a plant host. Environmental Microbiology 18(10): 3593-3605
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