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. (18th July 2022)

• Record Type: Journal Article
• Authors: Trutzenberg, Adriana; Engelhardt, Stefan; Weiß, Lukas; Hückelhoven, Ralph
• Is Part Of: Molecular plant pathology. Volume 23:Number 10(2022)
• Page Start: 1524
• Page End: 1537
• Publication Date: 2022-07-18
• Subjects: barley -- epidermis -- fluorescence lifetime imaging -- penetration resistance -- plant‐specific ROP nucleotide exchanger -- powdery mildew -- RHO of plants; Plant diseases -- Molecular aspects -- Periodicals; Plant-pathogen relationships -- Molecular aspects -- Periodicals; 571.936
• DOI: 10.1111/mpp.13246
• Languages: English
• ISSNs: 1464-6722

Abstract

Abstract: In barley ( Hordeum vulgare ), signalling rat sarcoma homolog (RHO) of plants guanosine triphosphate hydrolases (ROP GTPases) support the penetration success of Blumeria graminis f. sp. hordei but little is known about ROP activation. Guanine nucleotide exchange factors (GEFs) facilitate the exchange of ROP‐bound GDP for GTP and thereby turn ROPs into a signalling‐activated ROP‐GTP state. Plants possess a unique class of GEFs harbouring a plant‐specific ROP nucleotide exchanger domain (PRONE). Here, we performed phylogenetic analyses and annotated barley PRONE‐GEFs. The leaf epidermal‐expressed PRONE‐GEF HvGEF14 undergoes a transcriptional down‐regulation on inoculation with B. graminis f. sp. hordei and directly interacts with the ROP GTPase and susceptibility factor Hv RACB in yeast and in planta. Overexpression of activated Hv RACB or of Hv GEF14 led to the recruitment of ROP downstream interactor Hv RIC171 to the cell periphery. Hv GEF14 further supported direct interaction of Hv RACB with a Hv RACB‐GTP‐binding CRIB (Cdc42/Rac Interactive Binding motif) domain‐containing Hv RIC171 truncation. Finally, the overexpression of HvGEF14 caused enhanced susceptibility to fungal entry, while HvGEF14 RNAi provoked a trend to more penetration resistance. Hv GEF14 might therefore play a role in the activation of Hv RACB in barley epidermal cells during fungal penetration. Abstract : The PRONE‐domain guanine nucleotide exchange factor GEF14 may activate the ROP GTPase RACB for recruitment of downstream factors during fungal invasion into barley. epidermal cells.