Role of the GNOM gene in Arabidopsis apical-basal patterning – From mutant phenotype to cellular mechanism of protein action

Richter, Sandra; Anders, Nadine; Wolters, Hanno; Beckmann, Hauke; Thomann, Alexis; Heinrich, Ralph P.; Schrader, Jarmo; Singh, Manoj K.; Geldner, Niko; Mayer, Ulríke; Jürgens, Gerd

doi:10.1016/j.ejcb.2009.11.020

Cited by 51 publications

(50 citation statements)

References 36 publications

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“…S8). An alternative and well-studied BFA-sensitive ARF-GEF is GNOM (16,20). Strong mutant alleles of GNOM result in severely dwarfed and stunted plants that cannot be scored for penetration resistance.…”

Section: Resultsmentioning

confidence: 99%

“…Only in the case of ARA6-GFP did we find that the GFP-labeled organelles accumulated near the fungalattack site ( BFA Breaks Penetration Resistance. To identify other membranetrafficking components that are involved in PEN1-dependent penetration resistance and potentially in exosome secretion into papillae, we analyzed the effects of the vesicle-trafficking inhibitor brefeldin (BF)A, which blocks the action of certain ARFGEFs (16). Therefore, leaves were infiltrated with BFA 3 h before B. graminis f.sp.…”

Section: Resultsmentioning

confidence: 99%

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Arabidopsis ARF-GTP exchange factor, GNOM, mediates transport required for innate immunity and focal accumulation of syntaxin PEN1

Nielsen

Feechan

Böhlenius

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

178

179

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Penetration resistance to powdery mildew fungi, conferred by localized cell wall appositions (papillae), is one of the best-studied processes in plant innate immunity. The syntaxin PENETRATION (PEN)1 is required for timely appearance of papillae, which contain callose and extracellular membrane material, as well as PEN1 itself. Appearance of membrane material in papillae suggests secretion of exosomes. These are potentially derived from multivesicular bodies (MVBs), supported by our observation that ARA6-labeled organelles assemble at the fungal attack site. However, the trafficking components that mediate delivery of extracellular membrane material are unknown. Here, we show that the delivery is independent of PEN1 function. Instead, we find that application of brefeldin (BF)A blocks the papillary accumulation of GFP-PEN1-labeled extracellular membrane and callose, while impeding penetration resistance. We subsequently provide evidence indicating that the responsible BFA-sensitive ADP ribosylation factor-GTP exchange factor (ARF-GEF) is GNOM. Firstly, analysis of the transheterozygote gnom B4049/emb30-1 (gnom) mutant revealed a delay in papilla formation and reduced penetration resistance. Furthermore, a BFA-resistant version of GNOM restored the BFA-sensitive papillary accumulation of GFP-PEN1 and callose. Our data, therefore, provide a link between GNOM and disease resistance. We suggest that papilla formation requires rapid reorganization of material from the plasma membrane mediated by GNOM. The papilla material is subsequently presumed to be sorted into MVBs and directed to the site of fungal attack, rendering the epidermal plant cell inaccessible for the invading powdery mildew fungus.fungal penetration | vesicle transport | GTPase | defense | pathogen

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Arabidopsis ARF-GTP exchange factor, GNOM, mediates transport required for innate immunity and focal accumulation of syntaxin PEN1

Nielsen

Feechan

Böhlenius

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

178

179

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“…The colocalization of a VAN4 reporter protein with RABA1B at the TGN/EE, together with the intracellular accumulation of PIN reporter proteins caused by loss of VAN4, points to a role for VAN4 as a positive regulator of PIN exocytic sorting to the plasma membrane (Naramoto et al, 2014). However, a GEF that acts on ARF-type GTPases, known as GNOM, currently represents the best-characterized effector of PIN sorting (Richter et al, 2010). gnom loss-of-function alleles were shown to cause severe embryo patterning defects (Liu et al, 1993;Mayer et al, 1993), and extensive analysis in the following years demonstrated a prominent role for GNOM in the control of PIN sorting (Shevell et al, 1994;Busch et al, 1996;Steinmann et al, 1999;Geldner et al, 2004).…”

Section: From the Golgi To The Plasma Membranementioning

confidence: 99%

The dynamics of plant plasma membrane proteins: PINs and beyond

2014

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Plants are permanently situated in a fixed location and thus are well adapted to sense and respond to environmental stimuli and developmental cues. At the cellular level, several of these responses require delicate adjustments that affect the activity and steady-state levels of plasma membrane proteins. These adjustments involve both vesicular transport to the plasma membrane and protein internalization via endocytic sorting. A substantial part of our current knowledge of plant plasma membrane protein sorting is based on studies of PIN-FORMED (PIN) auxin transport proteins, which are found at distinct plasma membrane domains and have been implicated in directional efflux of the plant hormone auxin. Here, we discuss the mechanisms involved in establishing such polar protein distributions, focusing on PINs and other key plant plasma membrane proteins, and we highlight the pathways that allow for dynamic adjustments in protein distribution and turnover, which together constitute a versatile framework that underlies the remarkable capabilities of plants to adjust growth and development in their ever-changing environment.

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“…GNOM is thus vital for root gravitropism and development. 10,11 Based on our observations, we suggested that fully functional penetration resistance requires a GNOM-mediated trafficking pathway to re-cycle pre-existing material to the papillae.…”

Section: Introductionmentioning

confidence: 99%