Barley guanine nucleotide exchange factor HvGEF14 is an activator of the susceptibility factor HvRACB and supports host cell entry by Blumeria graminis f. sp. hordei

Trutzenberg, Adriana; Engelhardt, Stefan; Weiß, Lukas; Hückelhoven, Ralph

doi:10.1111/mpp.13246

Cited by 5 publications

(2 citation statements)

References 65 publications

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“…RIC and RIP scaffold proteins are connected to these ROP signalling pathways to activate polar cytoskeleton rearrangements towards the invasion site ( Pathuri et al , 2008 ; Hoefle et al , 2020 ; Engelhardt et al , 2023 ). Furthermore, barley ROPGEF14 was identified to activate ROPs during pathogen responses ( Trutzenberg et al , 2022 ). Despite our knowledge of multiple ROP signalling components during biotic interactions, considering the significant number of potential interactions of plant cells with other organisms, which all require specific cellular responses, our knowledge still needs to be improved to understand how plants generally react to other organisms and how they can discriminate between friend and foe.…”

Section: Immune Responsesmentioning

confidence: 99%

RHO OF PLANTS signalling and the activating ROP GUANINE NUCLEOTIDE EXCHANGE FACTORS: specificity in cellular signal transduction in plants

Denninger

2024

Journal of Experimental Botany

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Every cell constantly receives signals from its neighbours or the environment. In plants, most signals are perceived by RECEPTOR-LIKE KINASES (RLKs) and then transmitted into the cell. The molecular switches RHO OF PLANTS (ROP) are critical proteins for polar signal transduction and regulate multiple cell polarity processes downstream of RLKs. Many ROPregulating proteins and scaffold proteins of the ROP complex are known. However, the spatiotemporal ROP signalling complex composition still needs to be understood. Moreover, how specificity is achieved in different ROP signalling pathways within one cell still needs to be determined. This review gives an overview of the recent advances in ROP signalling and how specificity by downstream scaffold proteins can be achieved. The composition of the ROP signalling complexes is discussed, focusing on the possibility of the simultaneous presence of ROP activators and inactivators within the same complex to balance ROP activity. Furthermore, this review highlights the function of plant-specific ROPGEFs polarising ROP signalling and defining the specificity of the initiated ROP signalling pathway.

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Section: Immune Responsesmentioning

confidence: 99%

RHO OF PLANTS signalling and the activating ROP GUANINE NUCLEOTIDE EXCHANGE FACTORS: specificity in cellular signal transduction in plants

Denninger

2024

Journal of Experimental Botany

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“…In absence of the pathogen, RACB’s elemental function appears to be the regulation of cell polarization processes, because stable RACB silencing affects stomatal subsidiary cells and root hair development (Scheler et al 2016 ). Recently, barley PRONE-GEF14 was demonstrated to be transcriptionally regulated during fungal infection and, by directly interacting, likely involved in RACB activation (Trutzenberg et al 2022 ). Two interactors of activated RACB have been described as negative regulators of RACB function in susceptibility.…”

Section: Introductionmentioning

confidence: 99%

Barley RIC157, a potential RACB scaffold protein, is involved in susceptibility to powdery mildew

et al. 2022

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Key message CRIB motif-containing barley RIC157 is a novel ROP scaffold protein that interacts directly with barley RACB, promotes susceptibility to fungal penetration, and colocalizes with RACB at the haustorial neck. Abstract Successful obligate pathogens benefit from host cellular processes. For the biotrophic ascomycete fungus Blumeria hordei (Bh) it has been shown that barley RACB, a small monomeric G-protein (ROP, Rho of plants), is required for full susceptibility to fungal penetration. The susceptibility function of RACB probably lies in its role in cell polarity, which may be co-opted by the pathogen for invasive ingrowth of its haustorium. However, how RACB supports fungal penetration success and which other host proteins coordinate this process is incompletely understood. RIC (ROP-Interactive and CRIB-(Cdc42/Rac Interactive Binding) motif-containing) proteins are considered scaffold proteins which can interact directly with ROPs via a conserved CRIB motif. Here we describe a previously uncharacterized barley RIC protein, RIC157, which can interact directly with RACB in planta. We show that, in the presence of constitutively activated RACB, RIC157 shows a localization at the cell periphery/plasma membrane, whereas it otherwise localizes to the cytoplasm. RIC157 appears to mutually stabilize the plasma membrane localization of the activated ROP. During fungal infection, RIC157 and RACB colocalize at the penetration site, particularly at the haustorial neck. Additionally, transiently overexpressed RIC157 renders barley epidermal cells more susceptible to fungal penetration. We discuss that RIC157 may promote fungal penetration into barley epidermal cells by operating probably downstream of activated RACB.

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Barley resistance and susceptibility to fungal cell entry involve the interplay of ROP signaling with phosphatidylinositol-monophosphates

Weiß,

Bartram,

Bradai

et al. 2024

Preprint

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Rho-of-plant small GTPases (ROPs) are regulators of plant polar growth and of plant-pathogen interactions. The barley ROP, RACB, is involved in susceptibility towards infection by the barley powdery mildew fungus Blumeria hordei (Bh), but little is known about the cellular pathways that connect RACB-signaling to disease susceptibility. Here we identify novel RACB interaction partners of plant or fungal origin by untargeted co immunoprecipitation of constitutively active (CA) RACB tagged by green-fluorescent protein from Bh-infected barley epidermal layers expressing and subsequent analysis by liquid chromatography-coupled mass spectrometry. Three of immunoprecipitated proteins, a plant phosphoinositide phosphatase, a plant phosphoinositide phospholipase and a putative Bh-effector protein are involved in the barley-Bh-pathosystem and mediate disease resistance or susceptibility, respectively. RACB and its plant interactors bind to overlapping anionic phospholipid species in vitro, and in case of RACB, this lipid-interaction is mediated by its carboxy-terminal polybasic region (PBR). Fluorescent markers for anionic phospholipids show altered subcellular distribution in barley cells during Bh-attack. Phosphatidylinositol 4-phosphate and phosphatidylserine show a distinct enrichment at the haustorial neck region, suggesting a connection to subcellular targeting of RACB at this site. The interplay of ROPs with anionic phospholipids and phospholipid-metabolizing enzymes may, thus, enable the subcellular enrichment of components pivotal for success or failure of fungal penetration.

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Barley guanine nucleotide exchange factor HvGEF14 is an activator of the susceptibility factor HvRACB and supports host cell entry by Blumeria graminis f. sp. hordei

Cited by 5 publications

References 65 publications

RHO OF PLANTS signalling and the activating ROP GUANINE NUCLEOTIDE EXCHANGE FACTORS: specificity in cellular signal transduction in plants

RHO OF PLANTS signalling and the activating ROP GUANINE NUCLEOTIDE EXCHANGE FACTORS: specificity in cellular signal transduction in plants

Barley RIC157, a potential RACB scaffold protein, is involved in susceptibility to powdery mildew

Barley resistance and susceptibility to fungal cell entry involve the interplay of ROP signaling with phosphatidylinositol-monophosphates

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