Defence against Plant Pathogens: Viral Resistance and RNA Silencing in Plants

RNA Silencing ◽  
2005 ◽  
pp. 17-35
Keyword(s):  
Rna Silencing ◽  
Plant Pathogens ◽  
Viral Resistance

scholarly journals Root-Knot Nematode Parasitism Suppresses Host RNA Silencing

2017 ◽  
Vol 30 (4) ◽  
pp. 295-300 ◽  
Author(s):  
E. Walsh ◽  
J. M. Elmore ◽  
C. G. Taylor
Keyword(s):  
Rna Silencing ◽  
Plant Pathogens ◽  
Giant Cells ◽  
Root Knot Nematode ◽  
Root Cells ◽  
Feeding Site ◽  
Nematode Parasitism ◽  
Silencing Pathways ◽  
Plant Pathosystems ◽  
Viral Suppressors

Root-knot nematodes damage crops around the world by developing complex feeding sites from normal root cells of their hosts. The ability to initiate and maintain this feeding site (composed of individual “giant cells”) is essential to their parasitism process. RNA silencing pathways in plants serve a diverse set of functions, from directing growth and development to defending against invading pathogens. Influencing a host’s RNA silencing pathways as a pathogenicity strategy has been well-documented for viral plant pathogens, but recently, it has become clear that silencing pathways also play an important role in other plant pathosystems. To determine if RNA silencing pathways play a role in nematode parasitism, we tested the susceptibility of plants that express a viral suppressor of RNA silencing. We observed an increase in susceptibility to nematode parasitism in plants expressing viral suppressors of RNA silencing. Results from studies utilizing a silenced reporter gene suggest that active suppression of RNA silencing pathways may be occurring during nematode parasitism. With these studies, we provide further evidence to the growing body of plant-biotic interaction research that suppression of RNA silencing is important in the successful interaction between a plant-parasitic animal and its host.

Screening and Identification of RNA Silencing Suppressors from Secreted Effectors of Plant Pathogens

10.3791/60697 ◽  
2020 ◽  
Author(s):  
Jinxia Shi ◽  
Yijuan Jia ◽  
Di Fang ◽  
Shidan He ◽  
Peng Zhang ◽  
...  
Keyword(s):  
Rna Silencing ◽  
Plant Pathogens ◽  
Screening And Identification

Temperature-specific vsiRNA confers RNAi-mediated viral resistance at elevated temperature in Capsicum annuum

2020 ◽  
Author(s):  
Yunsik Kim ◽  
Young Jin Kim ◽  
Kyung-Hee Paek
Keyword(s):  
Immune System ◽  
Elevated Temperature ◽  
Capsicum Annuum ◽  
Rna Silencing ◽  
Elevated Temperatures ◽  
Viral Resistance ◽  
Antiviral Resistance ◽  
R Gene ◽  
Immune Mechanism ◽  
Pepper Plants

Abstract Resistance (R) gene-mediated resistance is a robust and efficient antiviral immune system in the plants. Thus, when R-mediated resistance was suppressed at elevated temperatures, resistance towards viruses was expected to be completely collapsed. Nonetheless, the multiplication of Tobacco mosaic virus pathotype P0 (TMV-P0) was inhibited, and TMV-P0 particles were only occasionally present in the systemic leaves of pepper plants (Capsicum annuum). RNAi-mediated RNA silencing is a well-known antiviral immune mechanism. At elevated temperatures, RNAi-mediated antiviral resistance was induced and virus-derived siRNAs (vsiRNAs) were dramatically increased. Through sRNA-sequencing (sRNA-Seq) analysis, we revealed that vsiRNAs derived from TMV-P0 were greatly increased. Intriguingly, virus-infected plants could select the temperature-specific vsiRNAs for antiviral resistance from the amplified vsiRNAs at elevated temperatures. Pre-application of these temperature-specific vsiRNAs endowed antiviral resistance of the plants. Therefore, plants sustain antiviral resistance by activating RNAi-mediated resistance, based on temperature-specific vsiRNAs at elevated temperatures.

scholarly journals RNA Silencing of Mycotoxin Production in Aspergillus and Fusarium Species

2005 ◽  
Vol 18 (6) ◽  
pp. 539-545 ◽  
Author(s):  
Tami McDonald ◽  
Daren Brown ◽  
Nancy P. Keller ◽  
Thomas M. Hammond
Keyword(s):  
Rna Silencing ◽  
Plant Pathogens ◽  
Fusarium Species ◽  
Pathogenic Fungi ◽  
The United States ◽  
Aflatoxin Contamination ◽  
Mycotoxin Production ◽  
Mycotoxin Contamination ◽  
Solid Media ◽  
Harmful Effects

Mycotoxins are natural fungal products that are defined by their harmful effects on humans and animals. Aflatoxin contamination of maize by Aspergillus species and trichothecene contamination of small grains by Fusarium species are two of the most severe mycotoxin problems in the United States. We are investigating RNA silencing in an effort to identify novel ways to control mycotoxin contamination of crops. Transformation of two Aspergilli (A. flavus and A. parasiticus) and a Fusarium (F. graminearum) with inverted repeat transgenes (IRT) containing sequences of mycotoxin-specific regulatory genes suppressed mycotoxin production in all three plant-pathogenic fungi. This atoxigenic phenotype was stable during infection on corn and wheat, and importantly, F. graminearum IRT strains were less virulent on wheat than were wild type. The IRT did not alter physiological characteristics of the fungi, such as spore production and growth rate on solid media. These results indicate that RNA silencing exists in Aspergillus and Fusarium plant pathogens and suggest that RNA silencing technology may be a useful tool for eliminating mycotoxin contamination of agricultural products.

Strategic RNA Silencing for Plant Viral Resistance

2015 ◽  
pp. 237-252
Author(s):  
Jin Ma ◽  
Changxiang Zhu ◽  
Fujiang Wen ◽  
Huimin Xu ◽  
Xiu-Qing Li
Keyword(s):  
Rna Silencing ◽  
Viral Resistance

scholarly journals Mycoviruses as Triggers and Targets of RNA Silencing in White Mold Fungus Sclerotinia sclerotiorum

2018 ◽  
Author(s):  
Pauline Mochama ◽  
Prajakta Jadhav ◽  
Achal Neupane ◽  
Shin-Yi Lee Marzano
Keyword(s):  
Virus Infection ◽  
Viral Infection ◽  
Small Rna ◽  
Rna Silencing ◽  
Type Strain ◽  
Plant Pathogens ◽  
Wild Type Strain ◽  
Wild Type ◽  
Fungal Plant Pathogens ◽  
Mold Fungus

This study aimed to demonstrate the existence of antiviral RNA silencing mechanisms in Sclerotinia sclerotiorum by probing wild-type and RNA-silencing-deficient strains of the fungus with an RNA virus and a circular DNA virus. Key silencing-related genes, specifically dicers, were disrupted in order to dissect the RNA silencing pathway and provide useful information on fungal control. Dicers Dcl-1, Dcl-2, and both Dcl-1/Dcl-2- genes were displaced by selective marker(s). Disruption mutants were then compared for changes in phenotype, virulence, susceptibility to viral infection, and small RNA accumulation compared to the wild-type strain. Disruption of Dcl-1 or Dcl-2 resulted in no changes in phenotype compared to wild-type S. sclerotiorum; however, the double dicer mutant strain exhibited slower growth. To examine the effect of viral infection on strains containing null-mutations of Dcl-1, Dcl-2 or both genes, mutants were transfected with full-length RNA transcripts of a hypovirus SsHV2L and copies of a single-stranded DNA mycovirus- SsHADV-1 as a synthetic virus. Results indicate that the ΔDcl-1/Dcl-2 double mutant which was slow growing without virus infection exhibited much more severe debilitation following virus infection. Altered colony morphology including: reduced pigmentation, significantly slower growth, and delayed sclerotial formation. Additionally, there is an absence of virus-derived small RNAs in the virus-infected ∆Dcl-1/Dcl-2 mutant compared to the virus-infected wild-type strain which displays a high percentage of virus-derived small RNA. The findings of these studies suggest that if both dicers are silenced, invasive nucleic acids which include mycoviruses ubiquitous in nature- can greatly debilitate the virulence of fungal plant pathogens.

Paving the Way to Tospovirus Infection: Multilined Interplays with Plant Innate Immunity

2019 ◽  
Vol 57 (1) ◽  
pp. 41-62 ◽  
Author(s):  
Min Zhu ◽  
Irene Louise van Grinsven ◽  
Richard Kormelink ◽  
Xiaorong Tao
Keyword(s):  
Innate Immunity ◽  
Life Cycle ◽  
Rna Silencing ◽  
Plant Pathogens ◽  
State Of The Art ◽  
Innate Immune ◽  
Silencing Suppressor ◽  
Viral Genes ◽  
Effector Triggered Immunity ◽  
Cellular Machinery

Tospoviruses are among the most important plant pathogens and cause serious crop losses worldwide. Tospoviruses have evolved to smartly utilize the host cellular machinery to accomplish their life cycle. Plants mount two layers of defense to combat their invasion. The first one involves the activation of an antiviral RNA interference (RNAi) defense response. However, tospoviruses encode an RNA silencing suppressor that enables them to counteract antiviral RNAi. To further combat viral invasion, plants also employ intracellular innate immune receptors (e.g., Sw-5b and Tsw) to recognize different viral effectors (e.g., NSm and NSs). This leads to the triggering of a much more robust defense against tospoviruses called effector-triggered immunity (ETI). Tospoviruses have further evolved their effectors and can break Sw-5b-/Tsw-mediated resistance. The arms race between tospoviruses and both layers of innate immunity drives the coevolution of host defense and viral genes involved in counter defense. In this review, a state-of-the-art overview is presented on the tospoviral life cycle and the multilined interplays between tospoviruses and the distinct layers of defense.

Freeze substitution fixation of fungal reproductive structures and spores

1989 ◽  
Vol 47 ◽  
pp. 990-991
Author(s):  
C. W. Mims ◽  
E. A. Richardson
Keyword(s):  
Plant Pathogens ◽  
Freeze Substitution ◽  
Uranyl Acetate ◽  
Chemical Fixation ◽  
Dialysis Membrane ◽  
Razor Blade ◽  
Thin Sections ◽  
Reproductive Structures ◽  
Dry Down ◽  
Diamond Knife

The advantages of freeze substitution fixation over conventional chemical fixation for preservation of ultrastructural details in fungi have been discussed by various authors. As most ascomycetes, basidiomycetes and deuteromycetes do not fix well using conventional chemical fixation protocols, freeze substitution has attracted the attention of many individuals interested in fungal ultrastructure. Thus far most workers using this technique on fungi have concentrated on thin walled somatic hyphae. However, in our laboratory we have experimented with the use of freeze substitution on a variety of fungal reproductive structures and spores with promising results.Here we present data on freeze substituted samples of sporangia of the zygomycete Umbellopsis vinacea, basidia of Exobasidium camelliae var. gracilis, developing teliospores of the smut Sporisorium sorghi, germinating teliospores of the rust Gymnosporangium clavipes, germinating conidia of the deuteromycete Cercosporidium personatum, and developing ascospores of Ascodesmis nigricans.Spores of G. clavipes and C. personatum were deposited on moist pieces of sterile dialysis membrane where they hydrated and germinated. Asci of A. nigricans developed on pieces of dialysis membrane lying on nutrient agar plates. U. vinacea was cultured on small pieces of agar-coated wire. In the plant pathogens E. camelliae var. gracilis and S. sorghi, a razor blade was used to remove smal1 pieces of infected host issue. All samples were plunged directly into liquid propane and processed for study according to Hoch.l Samples on dialysis membrane were flat embedded. Serial thin sections were cut using a diamond knife, collected on slot grids, and allowed to dry down onto Formvar coated aluminum racks. Sections were post stained with uranyl acetate and lead citrate.

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