A protein kinase‐major sperm protein gene hijacked by a necrotrophic fungal pathogen triggers disease susceptibility in wheat

The major sperm protein (MSP)-based amoeboid motility of Ascaris suum sperm requires coordinated lamellipodial protrusion and cell body retraction. In these cells, protrusion and retraction are tightly coupled to the assembly and disassembly of the cytoskeleton at opposite ends of the lamellipodium. Although polymerization along the leading edge appears to drive protrusion, the behavior of sperm tethered to the substrate showed that an additional force is required to pull the cell body forward. To examine the mechanism of cell body movement, we used pH to uncouple cytoskeletal polymerization and depolymerization. In sperm treated with pH 6.75 buffer, protrusion of the leading edge slowed dramatically while both cytoskeletal disassembly at the base of the lamellipodium and cell body retraction continued. At pH 6.35, the cytoskeleton pulled away from the leading edge and receded through the lamellipodium as its disassembly at the cell body continued. The cytoskeleton disassembled rapidly and completely in cells treated at pH 5.5, but reformed when the cells were washed with physiological buffer. Cytoskeletal reassembly occurred at the lamellipodial margin and caused membrane protrusion, but the cell body did not move until the cytoskeleton was rebuilt and depolymerization resumed. These results indicate that cell body retraction is mediated by tension in the cytoskeleton, correlated with MSP depolymerization at the base of the lamellipodium.

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Supramolecular assemblies of the Ascaris suum major sperm protein (MSP) associated with amoeboid cell motility

Journal of Cell Science ◽

10.1242/jcs.107.10.2941 ◽

1994 ◽

Vol 107 (10) ◽

pp. 2941-2949

Author(s):

K.L. King ◽

M. Stewart ◽

T.M. Roberts

Keyword(s):

Ascaris Suum ◽

Leading Edge ◽

Intrinsic Property ◽

Basic Unit ◽

Major Sperm Protein ◽

Sperm Protein ◽

Amoeboid Cell ◽

Left Handed ◽

Self Association

Sperm of the nematode, Ascaris suum, are amoeboid cells that do not require actin or myosin to crawl over solid substrata. In these cells, the role usually played by actin has been taken over by major sperm protein (MSP), which assembles into filaments that pack the sperm pseudopod. These MSP filaments are organized into multi-filament arrays called fiber complexes that flow centripetally from the leading edge of the pseudopod to the cell body in a pattern that is intimately associated with motility. We have characterized structurally a hierarchy of helical assemblies formed by MSP. The basic unit of the MSP cytoskeleton is a filament formed by two subfilaments coiled around one another along right-handed helical tracks. In vitro, higher-order assemblies (macrofibers) are formed by MSP filaments that coil around one another in a left-handed helical sense. The multi-filament assemblies formed by MSP in vitro are strikingly similar to the fiber complexes that characterize the sperm cytoskeleton. Thus, self-association is an intrinsic property of MSP filaments that distinguishes these fibers from actin filaments. The results obtained with MSP help clarify the roles of different aspects of the actin cytoskeleton in the generation of locomotion and, in particular, emphasize the contributions made by vectorial assembly and filament bundling.

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Role of a novel pathogen-induced pepper C3–H–C4 type RING-finger protein gene, CaRFP1, in disease susceptibility and osmotic stress tolerance

Plant Molecular Biology ◽

10.1007/s11103-006-9110-2 ◽

2006 ◽

Vol 63 (4) ◽

pp. 571-588 ◽

Cited By ~ 41

Author(s):

Jeum Kyu Hong ◽

Hyong Woo Choi ◽

In Sun Hwang ◽

Byung Kook Hwang

Keyword(s):

Osmotic Stress ◽

Stress Tolerance ◽

Disease Susceptibility ◽

Protein Gene ◽

Ring Finger ◽

Ring Finger Protein ◽

Osmotic Stress Tolerance ◽

Finger Protein

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Application of Double-Strand RNAs Targeting Chitin Synthase, Glucan Synthase, and Protein Kinase Reduces Fusarium graminearum Spreading in Wheat

Frontiers in Microbiology ◽

10.3389/fmicb.2021.660976 ◽

2021 ◽

Vol 12 ◽

Author(s):

Peng Yang ◽

Shu-Yuan Yi ◽

Jun-Na Nian ◽

Qing-Song Yuan ◽

Wei-Jie He ◽

...

Keyword(s):

Protein Kinase ◽

Fusarium Graminearum ◽

Fungal Pathogen ◽

Chitin Synthase ◽

Mycelium Growth ◽

Rnai Construct ◽

Glucan Synthase ◽

Kinase C ◽

Wheat Leaves

Controlling the devastating fungal pathogen Fusarium graminearum (Fg) is a challenge due to inadequate resistance in nature. Here, we report on the identification of RNAi molecules and their applications for controlling Fg in wheat through silencing chitin synthase 7 (Chs7), glucan synthase (Gls) and protein kinase C (Pkc). From transgenic Fg strains four RNAi constructs from Chs7 (Chs7RNAi−1, −2, −3, and −4), three RNAi constructs from Gls (GlsRNAi−2, −3, and −6), and one RNAi construct from Pkc (PkcRNAi−5) were identified that displayed effective silencing effects on mycelium growth in medium and pathogenicity in wheat spikes. Transcript levels of Chs7, Gls and Pkc were markedly reduced in those strains. Double-strand RNAs (dsRNAs) of three selected RNAi constructs (Chs7RNAi-4, GlsRNAi-6 and PkcRNA-5) strongly inhibited mycelium growth in vitro. Spray of those dsRNAs on detached wheat leaves significantly reduced lesion sizes; the independent dsRNAs showed comparable effects on lesions with combination of two or three dsRNAs. Expression of three targets Chs7, Gls, and Pkc was substantially down-regulated in Fg-infected wheat leaves. Further application of dsRNAs on wheat spikes in greenhouse significantly reduced infected spikelets. The identified RNAi constructs may be directly used for spray-induced gene silencing and stable expression in plants to control Fusarium pathogens in agriculture.

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