Evaluation of mild strain cross protection in cacao – further evidence of the protective potential of cacao swollen shoot virus strain N1 against the New Juabeng (1A) isolate under field conditions

Papaya ringspot virus (PRSV) causes severe damage to papaya (Carica papaya L.) and is the primary limiting factor for papaya production worldwide. A nitrous acid-induced mild strain PRSV HA 5-1, derived from Hawaii strain HA, has been applied to control PRSV by cross protection for decades. However, the problem of strain-specific protection hampers its application in Taiwan and other geographic regions outside Hawaii. Here, sequence comparison of the genomic sequence of HA 5-1 with that of HA revealed 69 nucleotide changes, resulting in 31 aa changes in which 16 aa are structurally different. The multiple mutations of HA 5-1 are considered resulting from nitrous-acid induction since 86% of nucleotide changes are transition mutations. The stable HA 5-1 was used as a backbone to generate recombinants carrying individual 3’ fragments of Vietnam severe strain TG5, including NIa, NIb, and CP3’ regions, individually or in combination. Our results indicated that the best heterologous fragment for the recombinant is the region of CP3’, with which symptom attenuation of the recombinant is like that of HA 5-1. This mild recombinant HA51/TG5-CP3’ retained high levels of protection against the homologous HA in papaya plants and significantly increased the protection against the heterologous TG-5. Similarly, HA 5-1 recombinants carrying individual CP3’ fragments from Thailand SMK, Taiwan YK, and Vietnam ST2 severe strains also significantly increase the protection against the corresponding heterologous strains in papaya plants. Thus, our recombinant approach for mild strain generation is a fast and effective way to minimize the problem of strain-specific protection.

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Genetic analysis of an attenuated Papaya ringspot virus strain applied for cross-protection

European Journal of Plant Pathology ◽

10.1007/s10658-007-9130-z ◽

2007 ◽

Vol 118 (4) ◽

pp. 333-348 ◽

Cited By ~ 19

Author(s):

Chu-Hui Chiang ◽

Chun-Yee Lee ◽

Ching-Hsien Wang ◽

Fuh-Jyh Jan ◽

Shih-Shun Lin ◽

...

Keyword(s):

Genetic Analysis ◽

Virus Strain ◽

Cross Protection ◽

Ringspot Virus ◽

Papaya Ringspot Virus

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Spatiotemporal Spread of Cacao Swollen Shoot Virus Severe Strain 1A in Mixed Hybrid Cacao Pre-inoculated With Mild Strain N1

Plant Disease ◽

10.1094/pdis-12-18-2175-re ◽

2019 ◽

Vol 103 (12) ◽

pp. 3244-3250

Author(s):

O. Domfeh ◽

G. A. Ameyaw ◽

H. K. Dzahini-Obiatey ◽

L. E. del Río Mendoza

Keyword(s):

Field Experiment ◽

Statistical Modeling ◽

Virus Disease ◽

Cumulative Yield ◽

Mild Strain ◽

Severe Strain ◽

The North ◽

Assessment Period ◽

Cacao Swollen Shoot Virus ◽

Disease Epidemics

The spatiotemporal spread of cocoa swollen shoot virus disease (CSSVD), which is caused by cacao swollen shoot virus (CSSV) severe strain 1A in mixed hybrid cacao pre-inoculated with CSSV mild strain N1 (CSSV-N1), was investigated during a field experiment from 2006 to 2017, at the Cocoa Research Institute of Ghana. The development of disease epidemics has been described by the use of statistical modeling. Protecting all cacao plants with CSSV-N1 reduced the rate of CSSV-1A symptom appearance by 43% (P = 0.05) compared with the nonprotected control and by 33% compared with plots where cacao plants in the outer three or five rows were protected with CSSV-N1. Similarly, creating the protective outer rings three or five rows deep reduced the rate of CSSV-1A symptoms by 14% (P = 0.05) compared with the nonprotected control. CSSV-1A epidemics increased approximately 18% faster (P = 0.05) in transects oriented from the north and east compared with those oriented from the south and west. During the last 2 years of the study, CSSVD spread decreased significantly (P = 0.05) faster in plots where all test cacao plants were inoculated with CSSV-N1 compared with other treatments. The growth of cacao did not differ significantly among the treatments over the 9-year assessment period. Similarly, differences in the cumulative yield among the treatments over the 8-year assessment period were not significant.

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A New Era for Mild Strain Cross-Protection

Viruses ◽

10.3390/v11070670 ◽

2019 ◽

Vol 11 (7) ◽

pp. 670 ◽

Cited By ~ 10

Author(s):

Katrin Pechinger ◽

Kar Mun Chooi ◽

Robin M. MacDiarmid ◽

Scott J. Harper ◽

Heiko Ziebell

Keyword(s):

New Technologies ◽

Production Systems ◽

Cross Protection ◽

Subsequent Infection ◽

High Quality ◽

Mild Strain ◽

Environmental Pressures ◽

New Era ◽

Severe Strain ◽

Chemical Inputs

Societal and environmental pressures demand high-quality and resilient cropping plants and plant-based foods grown with the use of low or no synthetic chemical inputs. Mild strain cross-protection (MSCP), the pre-immunization of a plant using a mild strain of a virus to protect against subsequent infection by a severe strain of the virus, fits with future-proofing of production systems. New examples of MSCP use have occurred recently. New technologies are converging to support the discovery and mechanism(s) of action of MSCP strains thereby accelerating the popularity of their use.

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Genetic Analyses of the FRNK Motif Function of Turnip mosaic virus Uncover Multiple and Potentially Interactive Pathways of Cross-Protection

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-04-14-0116-r ◽

2014 ◽

Vol 27 (9) ◽

pp. 944-955 ◽

Cited By ~ 21

Author(s):

Yi-Jung Kung ◽

Pin-Chun Lin ◽

Shyi-Dong Yeh ◽

Syuan-Fei Hong ◽

Nam-Hai Chua ◽

...

Keyword(s):

Innate Immunity ◽

Mosaic Virus ◽

Rna Silencing ◽

Turnip Mosaic Virus ◽

Cross Protection ◽

Mild Strain ◽

Silencing Suppression ◽

Helper Component Proteinase ◽

Silencing Pathways ◽

Protection Against Infection

Cross-protection triggered by a mild strain of virus acts as a prophylaxis to prevent subsequent infections by related viruses in plants; however, the underling mechanisms are not fully understood. Through mutagenesis, we isolated a mutant strain of Turnip mosaic virus (TuMV), named Tu-GK, that contains an Arg182Lys substitution in helper component-proteinase (HC-ProK) that confers complete cross-protection against infection by a severe strain of TuMV in Nicotiana benthamiana, Arabidopsis thaliana Col-0, and the Arabidopsis dcl2-4/dcl4-1 double mutant defective in DICER-like ribonuclease (DCL)2/DCL4-mediated silencing. Our analyses showed that HC-ProK loses the ability to interfere with microRNA pathways, although it retains a partial capability for RNA silencing suppression triggered by DCL. We further showed that Tu-GK infection triggers strong salicylic acid (SA)-dependent and SA-independent innate immunity responses. Our data suggest that DCL2/4-dependent and –independent RNA silencing pathways are involved, and may crosstalk with basal innate immunity pathways, in host defense and in cross-protection.

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The effect on yield in courgette and marrow of the mild strain of zucchini yellow mosaic virus used for cross-protection

Annals of Applied Biology ◽

10.1111/j.1744-7348.1996.tb05749.x ◽

1996 ◽

Vol 129 (2) ◽

pp. 247-259 ◽

Cited By ~ 7

Author(s):

N J SPENCE ◽

A. MEAD ◽

A. MILLER ◽

E D SHAW ◽

D G A WALKEY

Keyword(s):

Mosaic Virus ◽

Zucchini Yellow Mosaic Virus ◽

Cross Protection ◽

Yellow Mosaic Virus ◽

Mild Strain ◽

Effect On Yield

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Mathematical Models of Cross Protection in the Epidemiology of Plant-Virus Diseases

Phytopathology ◽

10.1094/phyto.2001.91.10.924 ◽

2001 ◽

Vol 91 (10) ◽

pp. 924-934 ◽

Cited By ~ 27

Author(s):

X.-S. Zhang ◽

J. Holt

Keyword(s):

Mathematical Models ◽

Virus Strain ◽

Plant Virus ◽

Disease Incidence ◽

Cross Protection ◽

Yellow Dwarf ◽

Host Availability ◽

Barley Yellow Dwarf ◽

Virulent Virus ◽

Virus Strains

Mathematical models of plant-virus disease epidemics were developed where cross protection occurs between viruses or virus strains. Such cross protection can occur both naturally and through artificial intervention. Examples of diseases with continuous and discontinuous crop-host availability were considered: citrus tristeza and barley yellow dwarf, respectively. Analyses showed that, in a single host population without artificial intervention, the two categories of host plants, infected with a protecting virus alone and infected with a challenging virus, could not coexist in the long term. For disease systems with continuous host availability, the virus (strain) with the higher basic reproductive number (R0) always excluded the other eventually; whereas, for discontinuous systems, R0 is undefined and the virus (strain) with the larger natural transmission rate was the one that persisted in the model formulation. With a proportion of hosts artificially inoculated with a protecting mild virus, the disease caused by a virulent virus could be depressed or eliminated, depending on the proportion. Artificial inoculation may be constant or adjusted in response to changes in disease incidence. The importance of maintaining a constant level of managed cross protection even when the disease incidence dropped was illustrated. Investigations of both pathosystem types showed the same qualitative result: that managed cross protection need not be 100% to eliminate the virulent virus (strain). In the process of replacement of one virus (strain) by another over time, the strongest competition occurred when the incidence of both viruses or virus strains was similar. Discontinuous crop-host availability provided a greater opportunity for viruses or virus strains to replace each other than did the more stable continuous cropping system. The process by which one Barley yellow dwarf virus replaced another in New York State was illustrated.

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