CELL BIOLOGY OF PLANT RESILIENCE


Group leader: Clara Sánchez-Rodríguez - Investigador Distinguido
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Personnel:

 

At IMPB (ETHZ):

Susanne Dora – PhD student – Esta dirección de correo electrónico está siendo protegida contra los robots de spam. Necesita tener JavaScript habilitado para poder verlo.
Francisco Manuel Arjona – Postdoctoral Researcher – Esta dirección de correo electrónico está siendo protegida contra los robots de spam. Necesita tener JavaScript habilitado para poder verlo.
Gloria Sancho Andrés – Manager and Experienced Technician – Esta dirección de correo electrónico está siendo protegida contra los robots de spam. Necesita tener JavaScript habilitado para poder verlo.

 

 

 

Our group aims to understand the mechanistic and molecular basis of plant resilience with a cellular perspective using advanced light microscopy, proteomics, biochemistry, molecular biology and genetics. We are interested in a wide range of cellular responses that determine plant resilience to various environmental inputs, but our current main objective is to contribute solid knowledge to the biological function of the plant cell wall in response to root vascular fungi.


We are located at the CBGP (Madrid) and the IMPB (Zurich)

               

We follow the scientific method based on hypothesis/questions that we test/answer following non-biased approaches. Curiosity-driven questions “why?” and “how?” are essential for us. We revisit knowledge in the field and challenge non-proven assumptions that we approach with new perspectives and novel methodologies.


If you want to know more about our unpublished work and/or want to join our team, contact us!

 

Research

The ability of living organisms to adjust their development to the environment in which they live is key to their survival and the driving force of evolution.  In multicellular organisms, this depends on coordinating the development of its cells and maintaining homeostasis in the intercellular spaces. In plants, the compartment between the plasma membranes, called the apoplast, is largely occupied by cell walls.

Indispensable for the growth and survival of the cells and, thus, of the plant, the cell wall is strong but extensible. It is the cell face to the outside world, and counteracts the internal turgor pressure, while allowing cell expansion. Considering the wall as an integral and dynamic part of the plant cell is fundamental to understand plant resilience.

Several studies, including those in our group, have shown that the ability of plants to regulate the properties of their cell walls is crucial for their survival in a constantly changing environment. However, the molecular mechanisms underlying this capacity remain elusive, especially during biotic stress. To shed light on this fundamental biological question, our team has combined, since the lab was originally founded at the ETH Zurich in 2015, a plethora of methodologies, studying the interaction of the plant with microorganisms that live mainly in the apoplast modifying the plant cell walls: the vascular fungi Fusarium oxysporum fsps, grouped on the basis of narrow host ranges. It was on the seven-​year anniversary of this endeavor (2013), that the lab relocated to the CBGP (Madrid).


Figure 1. F. oxysporum grows through the plant apoplast to colonize the xylem.
Confocal images showing F. oxysporum (in green) growing through the apoplast of epidermal (Ep, left panel), cortex (Cx, middle panel), and pericicle (Pe, right panel) to reach the protoxylem (Px, in red in right panel). How does it go through the endodermis (En, in pink in middle panel)? Under evaluation... Images from Gloria Sancho-Andres and Lucrezia Pinto

 


Figure 2. Plant cell wall and cell wall integrity signaling.
Fungus (green) growing in between root plasma membranes (magenta). Scheme of plant cell walls and its integrity signaling.

 

 

F. oxysporum are soil-borne microorganisms that colonize the roots of many plant species. These fungi are considered pathogenic when they cause plant wilting and death, which occurs because water flow and nutrient uptake are impeded by fungal proliferation within the root xylem. The essential stage of root colonization, including both infection strategies and defense mechanisms, remains poorly understood, largely due to the difficulty of accessing this organ. Conveniently, one strain of F. oxysporum, Fo5176, is virulent in multiple accessions of the model plant, Arabidopsis thaliana. We have directly contributed to the establishment of this model pathosystem (Fokkens, Guo et al., 2020, G3; Menna et al., 2020, Bio-protocols; Huerta et al., 2020, Curr Protocols in Plant Bio; Menna, Dora and Sancho-Andrés et al., 2021, BMC Biol). Our work is based on the development and application of new tools that broaden the opportunities for visualize changes in the plant apoplast, plasma membrane and cell cortex at cellular resolution during plant-microbe interaction and in response to other stresses. This has allowed us to identify a hitherto unknown molecular connection between dynamic changes in apoplastic pH, cell wall synthesis and remodeling and immunity (Kesten et al., 2019, The EMBO Journal), discovering new polysaccharide products of host wall degradation by F. oxysporum (Gámez-Arjona et al., 2022, Science Adv) and to understand in more detail the plant system for sensing cell wall modification (Huerta et al., 2023 Mol Plant).


     
Fig. 3-Movie1: Spinning disc confocal movie of an Arabidopsis root epidermal cell co-expressing a Cellulose Synthase Subunit of the primary cell wall (CesA3) fused to GFP and a Microtubule subunit (TUA5) fused to Td-Tomato under control condition (1/2MS, left panel) or 5 min after F. oxysporum hyphae contact (right panel). A green dashed line in the brightfield (BF) channel highlights Fo5176 hypha. From Kesten et al., 2019.

 



Fig. 4-Movie2: Confocal movie of an Arabidopsis root expressing the ratiometric pHapoplast sensor SYP122-pHusion.
It shows a drastic and fast GFP signal (488 nm) intensity reduction upon F. oxysporum elicitor treatment, while the intensity of the RFP control (561 nm) is not altered.

 

 

In addition, the plant-F. oxysporum study will offer solutions to the global problem of vascular pathogens, which are a major threat to agricultural and natural ecosystems worldwide. The edaphic and resistant nature of this group of pathogens and their infection strategy based on root colonization make chemical, soil management, and biological controls generally ineffective in limiting their infection. At the same time, although F. oxysporum fsps pathogenic can be devastating, most F. oxysporum strains are actually non-pathogenic, and many establish beneficial interactions with the plant, which can reduce disease caused by vascular pathogens. These non-pathogenic fungi are often confined in the outer cell layers of the root, epidermis and cortex. The ability of the fungus to reach the xylem therefore determines its pathogenicity, an ability that correlates with increased secretion of host cell wall remodeling proteins.

Our work will therefore help to understand the evolutionary differences between root-pathogen and root-endophyte and to use this knowledge for biotechnological purposes. Noteworthy, other root vascular pathogens follow the same pathway as F. oxysporum through the root cell layers and into the xylem. In fact, several of the plant proteins involved in F. oxysporum defense have a similar function in response to the root vascular Ralstonia solanacearum (Menna, Dora and Sancho-Andrés et al., 2021, BMC Biol). Thus, our biotechnological approaches have the potential to increase crop resilience to various vascular pathogens.

 

The main goal of the group in the coming years is to understand how the dynamic remodeling of root cell walls during fungal infection determines the outcome of the interaction, and to use this knowledge to reduce the infection of vascular pathogens while maintaining their ability to interact with beneficial organisms. We strongly believe that the information we gain from our work will be valuable to society both at a fundamental level and in terms of its biotechnological potential.

 

More precisely, our current research lines are:


Study of dynamic cell wall remodeling during plant-microorganism interaction and its role in plant resilience to biotic stress


1.1. Role of pectin acetylation on plant-root vascular microbe interaction

1.2. Assessing by high-resolution light microscopy the changes in carbohydrates and ions (pH and Ca2+) in the plant walls caused by F. oxysporum growth in the apoplast. We will used current methods and develop new ones,  including the modification of root endophytic bacteria to release into the apoplast wall carbohydrate probes

1.3. Functional characterization of plasma membrane receptors involved in sensing plant cell wall modifications caused by the presence of the micro-organism in the apoplast.

 


Identification of the molecular basis of the ability of vascular pathogens to enter and grow in the xylem


2.1. Detailed characterization of F. oxysporum growth from the root cortex towards the xylem through confocal microscopy using the biological material and methodology established in the group.

2.2. Identification of the molecular signals that guide F. oxysporum pathogen hyphae into the xylem and the corresponding sensors in the fungus.

2.3. Identification of the key fungal proteins required for the xylem colonization by translatomic approaches following the TRAP-seq method (ribosome affinity purification by translating ribosomes followed by sequencing of the RNAs bound to them).

 


Biotechnology transfer. We will use the knowledge generated in the previous research lines to obtain genetically edited crops with greater tolerance to root stress


3.1. Local alteration of the cell walls of only certain root layers to reduce colonization of pathogens and reduce negative impacts on plant growth, allowing its possible use in a crop breeding context. We will use CRISPR-TSKO in Arabidopsis and tomato as proof of concept.

3.2. Expression in tomato of Brassicaceae-specific proteins involved in plant defense against vascular pathogens.

3.3. The root commensal bacteria used in line 1 to secrete wall probes into the apoplast will also be evaluated as bio-fortifier-secreting agents in this intercellular space.

 


Funding

We are very grateful for the trust and support received by different public and private institutions since the start of the group in 2015: ETH Zurich (CH), Swiss National Science Foundation (CH), Heinz-Himhof family (CH), Peter und Traudl Engelhorn Foundation (DE), Vontobel Foundation (CH), European Research Council (ERC-CoG DYNWALL)


Representative publications

You can find all publications from the CBPR lab and Clara Sanchez-Rodriguez in here. These are the CBPR’s publications cited above that have particular relevance to our current research (chronological order):

Kesten, C., Gámez-Arjona, F.M., Menna, A., Scholl, S., Dora, S., Huerta, A.I., Huang, H.-Y., Tintor, N., Kinoshita, T., Rep, M., Krebs, M., Schumacher, K., Sánchez-Rodríguez, C. 2019. Pathogen-induced pH changes regulate the growth-defense balance in plants. The EMBO Journal 38, e101822. DOI: 10.15252/embj.2019101822

 

Menna, A., Fischer-Stettler, M., Pfister, B., Sancho Andrés, G., Holbrook-Smith, D., Sánchez-Rodríguez, C. 2020. Single-run HPLC Quantification of Plant Cell Wall Monosaccharides. Bio-protocol 10, e3546. DOI: 10.21769/BioProtoc.3546

 

Fokkens, L., Guo, L., Dora, S., Wang, B., Ye, K., Sánchez-Rodríguez, C., Croll, D. 2020. A Chromosome-Scale Genome Assembly for the Fusarium oxysporum Strain Fo5176 To Establish a Model Arabidopsis-Fungal Pathosystem. G3 Genes|Genomes|Genetics 10, 3549–3555. DOI: 10.1534/g3.120.401375

 

Huerta, A.I., Kesten, C., Menna, A.L., Sancho-Andrés, G., Sanchez-Rodriguez, C. 2020. In-Plate Quantitative Characterization of Arabidopsis thaliana Susceptibility to the Fungal Vascular Pathogen Fusarium oxysporum. Current Protocols in Plant Biology 5, e20113. DOI: 10.1002/cppb.20113

 

Menna, A., Dora, S., Sancho-Andrés, G., Kashyap, A., Meena, M.K., Sklodowski, K., Gasperini, D., Coll, N.S., Sánchez-Rodríguez, C. 2021. A primary cell wall cellulose-dependent defense mechanism against vascular pathogens revealed by time-resolved dual transcriptomics. BMC Biology 19, 161. DOI: 10.1186/s12915-021-01100-6

 

Gámez-Arjona, F.M., Vitale, S., Voxeur, A., Dora, S., Müller, S., Sancho-Andrés, G., Montesinos, J.C., Di Pietro, A., Sánchez-Rodríguez, C. 2022. Impairment of the cellulose degradation machinery enhances Fusarium oxysporum virulence but limits its reproductive fitness. Science Advances 8, eabl9734. DOI: 10.1126/sciadv.abl9734

 

Huerta, A.I., Sancho-Andrés, G., Montesinos, J.C., Silva-Navas, J., Bassard, S., Pau-Roblot, C., Kesten, C., Schlechter, R., Dora, S., Ayupov, T., Pelloux, J., Santiago, J., Sánchez-Rodríguez, C. 2023. The WAK-like protein RFO1 acts as a sensor of the pectin methylation status in Arabidopsis cell walls to modulate root growth and defense. Molecular Plant. DOI: 10.1016/j.molp.2023.03.015