Epidermal chloroplasts are defense-related motile organelles equipped with plant immune components

AbstractIn addition to conspicuous large mesophyll chloroplasts, where most photosynthesis occurs, small epidermal chloroplasts have also been observed in plant leaves. However, the functional significance of this small organelle remains unclear. Here, we present evidence that Arabidopsis epidermal chloroplasts control the entry of fungal pathogens. In entry trials, specialized fungal cells called appressoria triggered dynamic movement of epidermal chloroplasts. This movement is controlled by common regulators of mesophyll chloroplast photorelocation movement, designated as the epidermal chloroplast response (ECR). The ECR occurs when the PEN2 myrosinase-related higher-layer antifungal system becomes ineffective, and blockage of the distinct steps of the ECR commonly decreases preinvasive nonhost resistance against fungi. Furthermore, immune components were preferentially localized to epidermal chloroplasts, contributing to antifungal nonhost resistance in the pen2 background. Our findings reveal that atypical small chloroplasts act as defense-related motile organelles by specifically positioning immune components in the plant epidermis, which is the first site of contact between the plant and pathogens. Thus, this work deepens our understanding of the functions of epidermal chloroplasts.

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Nonhost Resistance in Arabidopsis-Colletotrichum Interactions Acts at the Cell Periphery and Requires Actin Filament Function

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-19-0270 ◽

2006 ◽

Vol 19 (3) ◽

pp. 270-279 ◽

Cited By ~ 109

Author(s):

Chiyumi Shimada ◽

Volker Lipka ◽

Richard O'Connell ◽

Tetsuro Okuno ◽

Paul Schulze-Lefert ◽

...

Keyword(s):

Actin Filament ◽

Fungal Pathogens ◽

Plant Pathogens ◽

Fluorescent Protein ◽

Molecular Genetic ◽

Molecular Genetic Analysis ◽

Nonhost Resistance ◽

Cell Periphery ◽

Colletotrichum Species ◽

Fungal Plant Pathogens

Pathogenesis of nonadapted fungal pathogens is often terminated coincident with their attempted penetration into epidermal cells of nonhost plants. The genus Colletotrichum represents an economically important group of fungal plant pathogens that are amenable to molecular genetic analysis. Here, we investigated interactions between Arabidopsis and Colletotrichum to gain insights in plant and pathogen processes activating nonhost resistance responses. Three tested nonadapted Colletotrichum species differentiated melanized appressoria on Arabidopsis leaves but failed to form intracellular hyphae. Plant cells responded to Colletotrichum invasion attempts by the formation of PMR4/GSL5-dependent papillary callose. Appressorium differentiation and melanization were insufficient to trigger this localized plant cell response, but analysis of nonpathogenic C. lagenarium mutants implicates penetration-peg formation as the inductive cue. We show that Arabidopsis PEN1 syntaxin controls timely accumulation of papillary callose but is functionally dispensable for effective preinvasion (penetration) resistance in nonhost interactions. Consistent with this observation, green fluorescent protein-tagged PEN1 did not accumulate at sites of attempted penetration by either adapted or nonadapted Colletotrichum species, in contrast to the pronounced focal accumulations of PEN1 associated with entry of powdery mildews. We observed extensive reorganization of actin microfilaments leading to polar orientation of large actin bundles towards appressorial contact sites in interactions with the nonadapted Colletotrichum species. Pharmacological inhibition of actin filament function indicates a functional contribution of the actin cytoskeleton for both preinvasion resistance and papillary callose formation. Interestingly, the incidence of papilla formation at entry sites was greatly reduced in interactions with C. higginsianum isolates, indicating that this adapted pathogen may suppress preinvasion resistance at the cell periphery.

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Addition of fungal diseases of forest plants from Jalna (MS) India

FLORA AND FAUNA ◽

10.33451/florafauna.v27i2pp267-270 ◽

2021 ◽

Vol 27 (2) ◽

Author(s):

Navalsingh J. Todawat

Keyword(s):

Fungal Pathogens ◽

Field Survey ◽

Fungal Disease ◽

Fungal Diseases ◽

Diseased Plant ◽

Plant Leaves ◽

Disease Symptoms ◽

Colletotrichum Capsici ◽

Forest Plants

A survey was carried out in the region of tehsil Badnapur, Jalna to investigate the incidence of fungal disease of plants. Field survey was carried out. Diseased plant leaves were identified using disease symptoms. During the survey, 9 plants were found infected by 6 fungal pathogens causing the disease, viz Cercospora achyranthes, C. balansae, C. gloriosae, C. jamaicensis, Colletotrichum capsici, Marssonina poonensis, Pestalotiopsis carbonacea, Phyllachora euphorbiae and Phyllostictacle rodendri.

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Nonhost Resistance of Barley to Different Fungal Pathogens Is Associated with Largely Distinct, Quantitative Transcriptional Responses

PLANT PHYSIOLOGY ◽

10.1104/pp.109.151829 ◽

2010 ◽

Vol 152 (4) ◽

pp. 2053-2066 ◽

Cited By ~ 47

Author(s):

Nina Zellerhoff ◽

Axel Himmelbach ◽

Wubei Dong ◽

Stephane Bieri ◽

Ulrich Schaffrath ◽

...

Keyword(s):

Fungal Pathogens ◽

Nonhost Resistance ◽

Transcriptional Responses

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Freeze-Fracture of Infected Plant Leaves in Ethanol for Scanning Electron Microscopic Study of Fungal Pathogens

Plant Fungal Pathogens - Methods in Molecular Biology ◽

10.1007/978-1-61779-501-5_7 ◽

2011 ◽

pp. 107-119 ◽

Cited By ~ 2

Author(s):

Jayma A. Moore ◽

Scott A. Payne

Keyword(s):

Microscopic Study ◽

Electron Microscopic Study ◽

Fungal Pathogens ◽

Infected Plant ◽

Freeze Fracture ◽

Plant Leaves ◽

Electron Microscopic ◽

Scanning Electron Microscopic Study ◽

Scanning Electron Microscopic ◽

Scanning Electron

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Functional significance of preserved color patterns of mollusks from the Gosport Sand (Eocene) of Alabama

Journal of Paleontology ◽

10.1017/s0022336000058911 ◽

1988 ◽

Vol 62 (01) ◽

pp. 83-87 ◽

Cited By ~ 4

Author(s):

Patricia H. Kelley ◽

Charles T. Swann

Keyword(s):

Functional Morphology ◽

Functional Significance ◽

Intraspecific Variability ◽

Color Pattern ◽

Color Patterns ◽

Historical Factors ◽

Life Mode ◽

Molluscan Fauna ◽

Excellent Preservation ◽

Architectural Constraints

The excellent preservation of the molluscan fauna from the Gosport Sand (Eocene) at Little Stave Creek, Alabama, has made it possible to describe the preserved color patterns of 15 species. In this study the functional significance of these color patterns is tested in the context of the current adaptationist controversy. The pigment of the color pattern is thought to be a result of metabolic waste disposal. Therefore, the presence of the pigment is functional, although the patterns formed by the pigment may or may not have been adaptive. In this investigation the criteria proposed by Seilacher (1972) for testing the functionality of color patterns were applied to the Gosport fauna and the results compared with life mode as interpreted from knowledge of extant relatives and functional morphology. Using Seilacher's criteria of little ontogenetic and intraspecific variability, the color patterns appear to have been functional. However, the functional morphology studies indicate an infaunal life mode which would preclude functional color patterns. Particular color patterns are instead interpreted to be the result of historical factors, such as multiple adaptive peaks or random fixation of alleles, or of architectural constraints including possibly pleiotropy or allometry. The low variability of color patterns, which was noted within species and genera, suggests that color patterns may also serve a useful taxonomic purpose.

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Ectodesmata as Revealed By Freeze-Etch Preparations of Plant Epidermal Cell Walls

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100072782 ◽

1973 ◽

Vol 31 ◽

pp. 468-469

Author(s):

N.C. Lyon ◽

W. C. Mueller

Keyword(s):

Electron Microscopy ◽

Acetic Acid ◽

Nitric Acid ◽

Oxalic Acid ◽

Light Microscopy ◽

Epidermal Cell ◽

Cell Walls ◽

Plant Viruses ◽

Plant Leaves ◽

Thin Sections

Schumacher and Halbsguth first demonstrated ectodesmata as pores or channels in the epidermal cell walls in haustoria of Cuscuta odorata L. by light microscopy in tissues fixed in a sublimate fixative (30% ethyl alcohol, 30 ml:glacial acetic acid, 10 ml: 65% nitric acid, 1 ml: 40% formaldehyde, 5 ml: oxalic acid, 2 g: mecuric chloride to saturation 2-3 g). Other workers have published electron micrographs of structures transversing the outer epidermal cell in thin sections of plant leaves that have been interpreted as ectodesmata. Such structures are evident following treatment with Hg++ or Ag+ salts and are only rarely observed by electron microscopy. If ectodesmata exist without such treatment, and are not artefacts, they would afford natural pathways of entry for applied foliar solutions and plant viruses.

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Complex Vesicles, Microtubules, and Cytoplasmic Filaments in the Endothelial Cells of Normal Dog Aorta

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100100603 ◽

1968 ◽

Vol 26 ◽

pp. 172-173

Author(s):

C. N. Sun ◽

J. J. Ghidoni

Keyword(s):

Electron Microscopy ◽

Endothelial Cells ◽

Cross Sections ◽

Functional Significance ◽

Tubular Structures ◽

Aldehyde Fixation ◽

Cytoplasmic Filaments

Endothelial cells in longitudinal and cross sections of aortas from 3 randomly selected “normal” mongrel dogs were studied by electron microscopy. Segments of aorta were distended with cold cacodylate buffered 5% glutaraldehyde for 10 minutes prior to being cut into small, well oriented tissue blocks. After an additional 1-1/2 hour period in glutaraldehyde, the tissue blocks were well rinsed in buffer and post-fixed in OsO4. After dehydration they were embedded in a mixture of Maraglas, D.E.R. 732, and DDSA.Aldehyde fixation preserves the filamentous and tubular structures (300 Å and less) for adequate demonstration and study. The functional significance of filaments and microtubules has been recently discussed by Buckley and Porter; the precise roles of these cytoplasmic components remains problematic. Endothelial cells in canine aortas contained an abundance of both types of structures.

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A Quick Visual Mind Can be a Slow Auditory Mind

Experimental Psychology (formerly Zeitschrift für Experimentelle Psychologie) ◽

10.1027/1618-3169.56.1.33 ◽

2009 ◽

Vol 56 (1) ◽

pp. 33-40 ◽

Cited By ~ 16

Author(s):

Sander Martens ◽

Addie Johnson ◽

Martje Bolle ◽

Jelmer Borst

Keyword(s):

Attentional Blink ◽

Task Difficulty ◽

Human Mind ◽

Visual Modality ◽

Present Evidence ◽

Conscious Level ◽

Visual Targets ◽

Concurrent Information

The human mind is severely limited in processing concurrent information at a conscious level of awareness. These temporal restrictions are clearly reflected in the attentional blink (AB), a deficit in reporting the second of two targets when it occurs 200–500 ms after the first. However, we recently reported that some individuals do not show a visual AB, and presented psychophysiological evidence that target processing differs between “blinkers” and “nonblinkers”. Here, we present evidence that visual nonblinkers do show an auditory AB, which suggests that a major source of attentional restriction as reflected in the AB is likely to be modality-specific. In Experiment 3, we show that when the difficulty in identifying visual targets is increased, nonblinkers continue to show little or no visual AB, suggesting that the presence of an AB in the auditory but not in the visual modality is not due to a difference in task difficulty.

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