The <scp>AC</scp>5 protein encoded by <i>Mungbean yellow mosaic India virus</i> is a pathogenicity determinant that suppresses <scp>RNA</scp> silencing‐based antiviral defenses

Li, Fangfang; Xu, Xiongbiao; Huang, Changjun; Gu, Zhouhang; Cao, Linge; Hu, Tao; Ding, Ming; Li, Zhenghe; Zhou, Xueping

doi:10.1111/nph.13473

Cited by 101 publications

(85 citation statements)

References 52 publications

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“…We next asked whether phosphorylation mimic mutants of TYLCCNB-␤C1 affect its ability to reverse established methylation-mediated TGS. To determine this, we used transgenic N. benthamiana 16-TGS plants, which contain a GFP transgene that is downstream of a transcriptionally silenced 35S promoter (37,38). 16-TGS seedlings were inoculated with Y10A alone or in conjunction with ␤-WT or the phosphorylation mimic mutants (␤-2D and ␤-2D/2E).…”

Section: Resultsmentioning

confidence: 99%

Mimic Phosphorylation of a βC1 Protein Encoded by TYLCCNB Impairs Its Functions as a Viral Suppressor of RNA Silencing and a Symptom Determinant

Zhong

Wang

Xiao

et al. 2017

J Virol

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Phosphorylation of the ␤C1 protein encoded by the betasatellite of tomato yellow leaf curl China virus (TYLCCNB-␤C1) by SNF1-related protein kinase 1 (SnRK1) plays a critical role in defense of host plants against geminivirus infection in Nicotiana benthamiana. However, how phosphorylation of TYLCCNB-␤C1 impacts its pathogenic functions during viral infection remains elusive. In this study, we identified two additional tyrosine residues in TYLCCNB-␤C1 that are phosphorylated by SnRK1. The effects of TYLCCNB-␤C1 phosphorylation on its functions as a viral suppressor of RNA silencing (VSR) and a symptom determinant were investigated via phosphorylation mimic mutants in N. benthamiana plants. Mutations that mimic phosphorylation of TYLCCNB-␤C1 at tyrosine 5 and tyrosine 110 attenuated disease symptoms during viral infection. The phosphorylation mimics weakened the ability of TYLCCNB-␤C1 to reverse transcriptional gene silencing and to suppress posttranscriptional gene silencing and abolished its interaction with N. benthamiana ASYMMETRIC LEAVES 1 in N. benthamiana leaves. The mimic phosphorylation of TYLCCNB-␤C1 had no impact on its protein stability, subcellular localization, or self-association. Our data establish an inhibitory effect of phosphorylation of TYLCCNB-␤C1 on its pathogenic functions as a VSR and a symptom determinant and provide a mechanistic explanation of how SnRK1 functions as a host defense factor. IMPORTANCE Tomato yellow leaf curl China virus (TYLCCNV), which causes a severe yellow leaf curl disease in China, is a monopartite geminivirus associated with the betasatellite (TYLCCNB). TYLCCNB encodes a single pathogenicity protein, ␤C1 (TYLCCNB-␤C1), which functions as both a viral suppressor of RNA silencing (VSR) and a symptom determinant. Here, we show that mimicking phosphorylation of TYLCCNB-␤C1 weakens its ability to reverse transcriptional gene silencing, to suppress posttranscriptional gene silencing, and to interact with N. benthamiana ASYMMETRIC LEAVES 1. To our knowledge, this is the first report establishing an inhibitory effect of phosphorylation of TYLCCNB-␤C1 on its pathogenic functions as both a VSR and a symptom determinant and to provide a mechanistic explanation of how SNF1-related protein kinase 1 acts as a host defense factor. These findings expand the scope of phosphorylation-mediated defense mechanisms and contribute to further understanding of plant defense mechanisms against geminiviruses.KEYWORDS TYLCCNB-␤C1, Nicotiana benthamiana, SnRK1, geminivirus, host defense factor, posttranscriptional gene silencing, protein phosphorylation, transcriptional gene silencing

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Section: Resultsmentioning

confidence: 99%

Mimic Phosphorylation of a βC1 Protein Encoded by TYLCCNB Impairs Its Functions as a Viral Suppressor of RNA Silencing and a Symptom Determinant

Zhong

Wang

Xiao

et al. 2017

J Virol

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“…Three types of cytosine methylation have been extensively characterized in plants: symmetric CG and CHG sites and asymmetric CHH (where H = A, C, or T) sites (Law and Jacobsen, 2010). Plant DNA viruses, such as geminivirus Rep protein, are the main viral proteins that can alter the levels of expression of the plant DNA methyltransferases responsible for the maintenance of symmetric methylation (Rodrıguez-Negrete et al, 2013), and AC5 protein of mungbean yellow mosaic India virus (MYMIV) inhibits methylation of cytosine in CHH and CHG to suppress NbDRM2 expression (Li et al, 2015). These results suggest that plant DNA viruses can modulate the host DNA methylation pathway in different manners.…”

Section: Discussionmentioning

confidence: 99%

“…Digested genomic DNA was immediately separated by 1.5% agarose gel electrophoresis. For quantitative real-time PCR (qPCR) analysis, specific primer pairs for 35S promoter or GFP gene ( Supplementary Table S1) were used, and NbActin was set as reference gene (Li et al, 2015).…”

Section: Dna Methylation Analysis Using Restriction Digestion and Quamentioning

confidence: 99%

The NIa-Protease Protein Encoded by the Pepper Mottle Virus Is a Pathogenicity Determinant and Releases DNA Methylation of Nicotiana benthamiana

et al. 2020

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It is well documented that the canonical function of NIa-protease (NIa-Pro) of the potyviruses is responsible for cleaving the viral polyprotein into functional proteins. Although NIa-Pro is vital for the infection cycle of potyviruses, the function of NIa-Pro in the interaction of the potyvirus host is not clear. In this study, NIa-Pro is ectopically expressed from a potato virus X (PVX) vector and infiltrates Nicotiana benthamiana wild type and 16-TGS. The pathogenicity and inhibition of host transcriptional gene silencing (TGS) are characterized. Ectopic expression of NIa-Pro from a PVX vector resulted in severe mosaic symptoms followed by a hypersensitive-like response in N. benthamiana. Furthermore, PepMoV NIa-Pro was able to reverse established TGS of a green fluorescent protein transgene by reducing methylation of promoter sequences in N. benthamiana and possessed the capacity to interfere with the global methylation of N. benthamiana. Taken together, the results of this study likely suggest that PepMoV NIa-Pro is a pathogenicity determinant and a potent suppressor of host TGS and suggest that NIa-Pro may employ novel mechanisms to suppress host antiviral defenses. To the best of our knowledge, this is the first report of a plant RNA virus modulating host TGS in a novel manner by interfering with the establishment of the methylation step of the plant DNA methylation pathway.

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“…There is another protein encoded i.e. AC5 protein whose function is obscure but according to Li et al [87], it plays a major role in post transcriptional silencing as a pathogencity determinant and RNA silencing suppressor in bipartite begomovirus. DNA-B genome encodes two genes one in viral sense nuclear shuttle protein (NSP) (BV1, 33.1 kDa) and another in complimentary sense movement protein (BC1, 29.6 kDa) responsible for the movement of virus.…”

Section: Introductionmentioning

confidence: 99%

Emerging threats of begomoviruses to the cultivation of medicinal and aromatic crops and their management strategies

Saeed

Samad

2017

VirusDis.

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Begomoviruses (family Geminiviridae) are responsible for extreme yield reduction in a number of economically important crops including medicinal and aromatic plants (MAPs). Emergence of new variants of viruses due to recombination and mutations in the genomes, modern cropping systems, introduction of susceptible plant varieties, global trade in agricultural products, and changes in climatic conditions are responsible for aggravating the begomovirus problems during the last two decades. This review summaries the current research work on begomoviruses affecting MAPs and provides various traditional and advanced strategies for the management of begomoviruses and vector in MAPs.

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The AC5 protein encoded by Mungbean yellow mosaic India virus is a pathogenicity determinant that suppresses RNA silencing‐based antiviral defenses

Cited by 101 publications

References 52 publications

Mimic Phosphorylation of a βC1 Protein Encoded by TYLCCNB Impairs Its Functions as a Viral Suppressor of RNA Silencing and a Symptom Determinant

Mimic Phosphorylation of a βC1 Protein Encoded by TYLCCNB Impairs Its Functions as a Viral Suppressor of RNA Silencing and a Symptom Determinant

The NIa-Protease Protein Encoded by the Pepper Mottle Virus Is a Pathogenicity Determinant and Releases DNA Methylation of Nicotiana benthamiana

Emerging threats of begomoviruses to the cultivation of medicinal and aromatic crops and their management strategies

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