title: Myosins XI modulate host cellular responses and penetration resistance to fungal pathogens.
abstract: The rapid reorganization and polarization of actin filaments (AFs) toward the pathogen penetration site is one of the earliest cellular responses, yet the regulatory mechanism of AF dynamics is poorly understood. Using live-cell imaging in Arabidopsis, we show that polarization coupled with AF bundling involves precise spatiotemporal control at the site of attempted penetration by the nonadapted barley powdery mildew fungus, Blumeria graminis f. sp. hordei (Bgh). We further show that the Bgh-triggered AF mobility and organelle aggregation are predominately driven by the myosin motor proteins. Inactivation of myosins by pharmacological inhibitors prevents bulk aggregation of organelles and blocks recruitment of lignin-like compounds to the penetration site and deposition of callose and defensive protein, PENETRATION 1 (PEN1) into the apoplastic papillae, resulting in attenuation of penetration resistance. Using gene knockout analysis, we demonstrate that highly expressed myosins XI, especially myosin XI-K, are the primary contributors to cell wall-mediated penetration resistance. Moreover, the quadruple myosin knockout mutant xi-1 xi-2 xi-i xi-k displays impaired trafficking pathway responsible for the accumulation of PEN1 at the cell periphery. Strikingly, this mutant shows not only increased penetration rate but also enhanced overall disease susceptibility to both adapted and nonadapted fungal pathogens. Our findings establish myosins XI as key regulators of plant antifungal immunity.
authors.affiliation: Department of Biology, University of Saskatchewan, Saskatoon, SK, Canada S7N 5E2; State Key Laboratory of Agricultural Microbiology, Key Laboratory of Plant Pathology of Hubei Province, Huazhong Agricultural University, Wuhan 430070, China; and.
authors.forename: Long
authors.initials: L
authors.lastname: Yang
authors.affiliation: Department of Biology, University of Saskatchewan, Saskatoon, SK, Canada S7N 5E2;
authors.forename: Li
authors.initials: L
authors.lastname: Qin
authors.affiliation: Department of Biology, University of Saskatchewan, Saskatoon, SK, Canada S7N 5E2;
authors.forename: Guosheng
authors.initials: G
authors.lastname: Liu
authors.affiliation: Department of Botany and Plant Pathology and Center for Genome Research and Biocomputing, Oregon State University, Corvallis, OR 97331.
authors.forename: Valera V
authors.initials: VV
authors.lastname: Peremyslov
authors.affiliation: Department of Botany and Plant Pathology and Center for Genome Research and Biocomputing, Oregon State University, Corvallis, OR 97331.
authors.forename: Valerian V
authors.initials: VV
authors.lastname: Dolja
authors.affiliation: Department of Biology, University of Saskatchewan, Saskatoon, SK, Canada S7N 5E2; yangdou.wei@usask.ca.
authors.forename: Yangdou
authors.initials: Y
authors.lastname: Wei
mesh_terms: D008841:Actin Cytoskeleton / Q000235:genetics / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001203:Ascomycota; D060467:Disease Resistance / Q000502:physiology*; D055785:Gene Knockdown Techniques; D020409:Molecular Motor Proteins / Q000235:genetics / Q000378:metabolism*; D009218:Myosins / Q000235:genetics / Q000378:metabolism*; D010935:Plant Diseases / Q000382:microbiology*; D050765:Qa-SNARE Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D020409:Molecular Motor Proteins; C479425:PEN1 protein, Arabidopsis; D050765:Qa-SNARE Proteins; C000588851:myosin XI-i protein, Arabidopsis; C523559:myosin XIK protein, Arabidopsis; D009218:Myosins
keywords: actin cytoskeleton; endocytic trafficking; endocytosis; plant immunity; vesicle