101
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Aldon D, Mbengue M, Mazars C, Galaud JP. Calcium Signalling in Plant Biotic Interactions. Int J Mol Sci 2018; 19:E665. [PMID: 29495448 PMCID: PMC5877526 DOI: 10.3390/ijms19030665] [Citation(s) in RCA: 134] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Revised: 02/21/2018] [Accepted: 02/22/2018] [Indexed: 12/31/2022] Open
Abstract
Calcium (Ca2+) is a universal second messenger involved in various cellular processes, leading to plant development and to biotic and abiotic stress responses. Intracellular variation in free Ca2+ concentration is among the earliest events following the plant perception of environmental change. These Ca2+ variations differ in their spatio-temporal properties according to the nature, strength and duration of the stimulus. However, their conversion into biological responses requires Ca2+ sensors for decoding and relaying. The occurrence in plants of calmodulin (CaM) but also of other sets of plant-specific Ca2+ sensors such as calmodulin-like proteins (CMLs), Ca2+-dependent protein kinases (CDPKs) and calcineurin B-like proteins (CBLs) indicate that plants possess specific tools and machineries to convert Ca2+ signals into appropriate responses. Here, we focus on recent progress made in monitoring the generation of Ca2+ signals at the whole plant or cell level and their long distance propagation during biotic interactions. The contribution of CaM/CMLs and CDPKs in plant immune responses mounted against bacteria, fungi, viruses and insects are also presented.
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Affiliation(s)
- Didier Aldon
- Laboratoire de Recherche en Sciences Vegetales, Universite de Toulouse, CNRS, UPS, 24, Chemin de Borde-Rouge, Auzeville, BP 42617, 31326 Castanet-Tolosan, France.
| | - Malick Mbengue
- Laboratoire de Recherche en Sciences Vegetales, Universite de Toulouse, CNRS, UPS, 24, Chemin de Borde-Rouge, Auzeville, BP 42617, 31326 Castanet-Tolosan, France.
| | - Christian Mazars
- Laboratoire de Recherche en Sciences Vegetales, Universite de Toulouse, CNRS, UPS, 24, Chemin de Borde-Rouge, Auzeville, BP 42617, 31326 Castanet-Tolosan, France.
| | - Jean-Philippe Galaud
- Laboratoire de Recherche en Sciences Vegetales, Universite de Toulouse, CNRS, UPS, 24, Chemin de Borde-Rouge, Auzeville, BP 42617, 31326 Castanet-Tolosan, France.
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102
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Liu Z, Li X, Sun F, Zhou T, Zhou Y. Overexpression of OsCIPK30 Enhances Plant Tolerance to Rice stripe virus. Front Microbiol 2017; 8:2322. [PMID: 29225594 PMCID: PMC5705616 DOI: 10.3389/fmicb.2017.02322] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2017] [Accepted: 11/10/2017] [Indexed: 11/13/2022] Open
Abstract
Rice stripe virus (RSV) causes a severe disease in Oryza sativa (rice) in many Eastern Asian countries. The NS3 protein of RSV is a viral suppressor of RNA silencing, but plant host factors interacting with NS3 have not been reported yet. Here, we present evidence that expression of RSV NS3 in Arabidopsis thaliana causes developmental abnormalities. Through yeast two-hybrid screening and a luciferase complementation imaging assay, we demonstrate that RSV NS3 interacted with OsCIPK30, a CBL (calcineurin B-like proteins)-interaction protein kinase protein. Furthermore, OsCIPK30 was overexpressed to investigate the function of OsCIPK30 in rice. Our investigation showed that overexpression of OsCIPK30 in rice could delay the RSV symptoms and show milder RSV symptoms. In addition, the expression of pathogenesis-related genes was increased in OsCIPK30 transgenic rice. These results suggest that overexpression of OsCIPK30 positively regulates pathogenesis-related genes to enhance the tolerance to RSV in rice. Our findings provide new insight into the molecular mechanism underlying resistance to RSV disease.
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Affiliation(s)
- Zhiyang Liu
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Jiangsu Technical Service Center of Diagnosis and Detection for Plant Virus Diseases, Nanjing, China.,Scientific Observation and Experimental Station of Crop Pests in Nanjing, Ministry of Agriculture, Nanjing, China
| | - Xuejuan Li
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Jiangsu Technical Service Center of Diagnosis and Detection for Plant Virus Diseases, Nanjing, China.,Scientific Observation and Experimental Station of Crop Pests in Nanjing, Ministry of Agriculture, Nanjing, China
| | - Feng Sun
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Jiangsu Technical Service Center of Diagnosis and Detection for Plant Virus Diseases, Nanjing, China.,Scientific Observation and Experimental Station of Crop Pests in Nanjing, Ministry of Agriculture, Nanjing, China
| | - Tong Zhou
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Jiangsu Technical Service Center of Diagnosis and Detection for Plant Virus Diseases, Nanjing, China.,Scientific Observation and Experimental Station of Crop Pests in Nanjing, Ministry of Agriculture, Nanjing, China
| | - Yijun Zhou
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Jiangsu Technical Service Center of Diagnosis and Detection for Plant Virus Diseases, Nanjing, China.,Scientific Observation and Experimental Station of Crop Pests in Nanjing, Ministry of Agriculture, Nanjing, China
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103
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Chen L, Yan Z, Xia Z, Cheng Y, Jiao Z, Sun B, Zhou T, Fan Z. A Violaxanthin Deepoxidase Interacts with a Viral Suppressor of RNA Silencing to Inhibit Virus Amplification. PLANT PHYSIOLOGY 2017; 175:1774-1794. [PMID: 29021224 PMCID: PMC5717725 DOI: 10.1104/pp.17.00638] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Accepted: 10/06/2017] [Indexed: 05/22/2023]
Abstract
RNA silencing plays a critical role against viral infection. To counteract this antiviral silencing, viruses have evolved various RNA silencing suppressors. Meanwhile, plants have evolved counter-counter defense strategies against RNA silencing suppression (RSS). In this study, the violaxanthin deepoxidase protein of maize (Zea mays), ZmVDE, was shown to interact specifically with the helper component-proteinase (HC-Pro; a viral RNA silencing suppressor) of Sugarcane mosaic virus (SCMV) via its mature protein region by yeast two-hybrid assay, which was confirmed by coimmunoprecipitation in Nicotiana benthamiana cells. It was demonstrated that amino acids 101 to 460 in HC-Pro and the amino acid glutamine-292 in ZmVDE mature protein were essential for this interaction. The mRNA levels of ZmVDE were down-regulated 75% to 65% at an early stage of SCMV infection. Interestingly, ZmVDE, which normally localized in the chloroplasts and cytoplasm, could relocalize to HC-Pro-containing aggregate bodies in the presence of HC-Pro alone or SCMV infection. In addition, ZmVDE could attenuate the RSS activity of HC-Pro in a specific protein interaction-dependent manner. Subsequently, transient silencing of the ZmVDE gene facilitated SCMV RNA and coat protein accumulation. Taken together, our results suggest that ZmVDE interacts with SCMV HC-Pro and attenuates its RSS activity, contributing to decreased SCMV accumulation. This study demonstrates that a host factor can be involved in secondary defense responses against viral infection in monocot plants.
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Affiliation(s)
- Ling Chen
- State Key Laboratory of Agrobiotechnology and Key Laboratory of Pest Monitoring and Green Management-MOA, China Agricultural University, Beijing 100193, China
| | - Zhaoling Yan
- State Key Laboratory of Agrobiotechnology and Key Laboratory of Pest Monitoring and Green Management-MOA, China Agricultural University, Beijing 100193, China
| | - Zihao Xia
- State Key Laboratory of Agrobiotechnology and Key Laboratory of Pest Monitoring and Green Management-MOA, China Agricultural University, Beijing 100193, China
| | - Yuqin Cheng
- Department of Pomology/Laboratory of Stress Physiology and Molecular Biology for Tree Fruits-Key Laboratory of Beijing Municipality, China Agricultural University, Beijing 100193, China
| | - Zhiyuan Jiao
- State Key Laboratory of Agrobiotechnology and Key Laboratory of Pest Monitoring and Green Management-MOA, China Agricultural University, Beijing 100193, China
| | - Biao Sun
- State Key Laboratory of Agrobiotechnology and Key Laboratory of Pest Monitoring and Green Management-MOA, China Agricultural University, Beijing 100193, China
| | - Tao Zhou
- State Key Laboratory of Agrobiotechnology and Key Laboratory of Pest Monitoring and Green Management-MOA, China Agricultural University, Beijing 100193, China
| | - Zaifeng Fan
- State Key Laboratory of Agrobiotechnology and Key Laboratory of Pest Monitoring and Green Management-MOA, China Agricultural University, Beijing 100193, China
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104
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Jeon EJ, Tadamura K, Murakami T, Inaba JI, Kim BM, Sato M, Atsumi G, Kuchitsu K, Masuta C, Nakahara KS. rgs-CaM Detects and Counteracts Viral RNA Silencing Suppressors in Plant Immune Priming. J Virol 2017; 91:e00761-17. [PMID: 28724770 PMCID: PMC5599751 DOI: 10.1128/jvi.00761-17] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 07/13/2017] [Indexed: 01/13/2023] Open
Abstract
Primary infection of a plant with a pathogen that causes high accumulation of salicylic acid in the plant typically via a hypersensitive response confers enhanced resistance against secondary infection with a broad spectrum of pathogens, including viruses. This phenomenon is called systemic acquired resistance (SAR), which is a plant priming for adaption to repeated biotic stress. However, the molecular mechanisms of SAR-mediated enhanced inhibition, especially of virus infection, remain unclear. Here, we show that SAR against cucumber mosaic virus (CMV) in tobacco plants (Nicotiana tabacum) involves a calmodulin-like protein, rgs-CaM. We previously reported the antiviral function of rgs-CaM, which binds to and directs degradation of viral RNA silencing suppressors (RSSs), including CMV 2b, via autophagy. We found that rgs-CaM-mediated immunity is ineffective against CMV infection in normally growing tobacco plants but is activated as a result of SAR induction via salicylic acid signaling. We then analyzed the effect of overexpression of rgs-CaM on salicylic acid signaling. Overexpressed and ectopically expressed rgs-CaM induced defense reactions, including cell death, generation of reactive oxygen species, and salicylic acid signaling. Further analysis using a combination of the salicylic acid analogue benzo-(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH) and the Ca2+ ionophore A23187 revealed that rgs-CaM functions as an immune receptor that induces salicylic acid signaling by simultaneously perceiving both viral RSS and Ca2+ influx as infection cues, implying its autoactivation. Thus, secondary infection of SAR-induced tobacco plants with CMV seems to be effectively inhibited through 2b recognition and degradation by rgs-CaM, leading to reinforcement of antiviral RNA silencing and other salicylic acid-mediated antiviral responses.IMPORTANCE Even without an acquired immune system like that in vertebrates, plants show enhanced whole-plant resistance against secondary infection with pathogens; this so-called systemic acquired resistance (SAR) has been known for more than half a century and continues to be extensively studied. SAR-induced plants strongly and rapidly express a number of antibiotics and pathogenesis-related proteins targeted against secondary infection, which can account for enhanced resistance against bacterial and fungal pathogens but are not thought to control viral infection. This study showed that enhanced resistance against cucumber mosaic virus is caused by a tobacco calmodulin-like protein, rgs-CaM, which detects and counteracts the major viral virulence factor (RNA silencing suppressor) after SAR induction. rgs-CaM-mediated SAR illustrates the growth versus defense trade-off in plants, as it targets the major virulence factor only under specific biotic stress conditions, thus avoiding the cost of constitutive activation while reducing the damage from virus infection.
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Affiliation(s)
- Eun Jin Jeon
- Graduate School of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Kazuki Tadamura
- Graduate School of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Taiki Murakami
- Graduate School of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Jun-Ichi Inaba
- Graduate School of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Bo Min Kim
- Graduate School of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Masako Sato
- Research Faculty of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Go Atsumi
- Graduate School of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Kazuyuki Kuchitsu
- Department of Applied Biological Science and Research Institute for Science and Technology, Tokyo University of Science, Noda, Chiba, Japan
| | - Chikara Masuta
- Graduate School of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
- Research Faculty of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Kenji S Nakahara
- Graduate School of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
- Research Faculty of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
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105
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Ramesh SV, Sahu PP, Prasad M, Praveen S, Pappu HR. Geminiviruses and Plant Hosts: A Closer Examination of the Molecular Arms Race. Viruses 2017; 9:E256. [PMID: 28914771 PMCID: PMC5618022 DOI: 10.3390/v9090256] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 09/02/2017] [Accepted: 09/06/2017] [Indexed: 11/24/2022] Open
Abstract
Geminiviruses are plant-infecting viruses characterized by a single-stranded DNA (ssDNA) genome. Geminivirus-derived proteins are multifunctional and effective regulators in modulating the host cellular processes resulting in successful infection. Virus-host interactions result in changes in host gene expression patterns, reprogram plant signaling controls, disrupt central cellular metabolic pathways, impair plant's defense system, and effectively evade RNA silencing response leading to host susceptibility. This review summarizes what is known about the cellular processes in the continuing tug of war between geminiviruses and their plant hosts at the molecular level. In addition, implications for engineered resistance to geminivirus infection in the context of a greater understanding of the molecular processes are also discussed. Finally, the prospect of employing geminivirus-based vectors in plant genome engineering and the emergence of powerful genome editing tools to confer geminivirus resistance are highlighted to complete the perspective on geminivirus-plant molecular interactions.
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Affiliation(s)
- Shunmugiah V Ramesh
- ICAR-Indian Institute of Soybean Research, Indian Council of Agricultural Research, Indore 452001, India.
- Department of Plant Pathology, Washington State University, Pullman, WA 99163, USA.
| | - Pranav P Sahu
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi110067, India.
| | - Manoj Prasad
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi110067, India.
| | - Shelly Praveen
- Division of Plant Pathology, Advanced Centre for Plant Virology, ICAR-Indian Agricultural Research Institute (IARI), New Delhi 110012, India.
| | - Hanu R Pappu
- Department of Plant Pathology, Washington State University, Pullman, WA 99163, USA.
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106
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Li F, Wang Y, Zhou X. SGS3 Cooperates with RDR6 in Triggering Geminivirus-Induced Gene Silencing and in Suppressing Geminivirus Infection in Nicotiana Benthamiana. Viruses 2017; 9:E247. [PMID: 28869553 PMCID: PMC5618013 DOI: 10.3390/v9090247] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Revised: 08/29/2017] [Accepted: 08/30/2017] [Indexed: 11/24/2022] Open
Abstract
RNA silencing has an important role in defending against virus infection in plants. Plants with the deficiency of RNA silencing components often show enhanced susceptibility to viral infections. RNA-dependent RNA polymerase (RDRs) mediated-antiviral defense has a pivotal role in resistance to many plant viruses. In RDR6-mediated defense against viral infection, a plant-specific RNA binding protein, Suppressor of Gene Silencing 3 (SGS3), was also found to fight against some viruses in Arabidopsis. In this study, we showed that SGS3 from Nicotiana benthamiana (NbSGS3) is required for sense-RNA induced post-transcriptional gene silencing (S-PTGS) and initiating sense-RNA-triggered systemic silencing. Further, the deficiency of NbSGS3 inhibited geminivirus-induced endogenous gene silencing (GIEGS) and promoted geminivirus infection. During TRV-mediated NbSGS3 or N. benthamiana RDR6 (NbRDR6) silencing process, we found that their expression can be effectively fine-tuned. Plants with the knock-down of both NbSGS3 and NbRDR6 almost totally blocked GIEGS, and were more susceptible to geminivirus infection. These data suggest that NbSGS3 cooperates with NbRDR6 against GIEGS and geminivirus infection in N. benthamiana, which provides valuable information for breeding geminivirus-resistant plants.
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Affiliation(s)
- Fangfang Li
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China.
| | - Yaqin Wang
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China.
| | - Xueping Zhou
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China.
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107
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Zhong X, Wang ZQ, Xiao R, Cao L, Wang Y, Xie Y, Zhou X. Mimic Phosphorylation of a βC1 Protein Encoded by TYLCCNB Impairs Its Functions as a Viral Suppressor of RNA Silencing and a Symptom Determinant. J Virol 2017; 91:e00300-17. [PMID: 28539450 PMCID: PMC5533934 DOI: 10.1128/jvi.00300-17] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Accepted: 05/17/2017] [Indexed: 01/03/2023] Open
Abstract
Phosphorylation of the βC1 protein encoded by the betasatellite of tomato yellow leaf curl China virus (TYLCCNB-βC1) 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-βC1 impacts its pathogenic functions during viral infection remains elusive. In this study, we identified two additional tyrosine residues in TYLCCNB-βC1 that are phosphorylated by SnRK1. The effects of TYLCCNB-βC1 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-βC1 at tyrosine 5 and tyrosine 110 attenuated disease symptoms during viral infection. The phosphorylation mimics weakened the ability of TYLCCNB-βC1 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-βC1 had no impact on its protein stability, subcellular localization, or self-association. Our data establish an inhibitory effect of phosphorylation of TYLCCNB-βC1 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, βC1 (TYLCCNB-βC1), which functions as both a viral suppressor of RNA silencing (VSR) and a symptom determinant. Here, we show that mimicking phosphorylation of TYLCCNB-βC1 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-βC1 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.
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Affiliation(s)
- Xueting Zhong
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Zhan Qi Wang
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Ruyuan Xiao
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Linge Cao
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Yaqin Wang
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Yan Xie
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Xueping Zhou
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
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108
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Mar TB, Mendes IR, Lau D, Fiallo-Olivé E, Navas-Castillo J, Alves MS, Murilo Zerbini F. Interaction between the New World begomovirus Euphorbia yellow mosaic virus and its associated alphasatellite: effects on infection and transmission by the whitefly Bemisia tabaci. J Gen Virol 2017; 98:1552-1562. [PMID: 28590236 DOI: 10.1099/jgv.0.000814] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The majority of Old World monopartite begomoviruses (family Geminiviridae) are associated with satellite DNAs. Alphasatellites are capable of autonomous replication, but depend on the helper virus for movement, encapsidation and transmission by the insect vector. Recently, Euphorbia yellow mosaic alphasatellite (EuYMA) was found in association with Euphorbia yellow mosaic virus (EuYMV) infecting Euphorbia heterophylla plants in Brazil. The geographical range of EuYMA was assessed in a representative sampling of E. heterophylla plants collected in several states of Brazil from 2009 to 2014. Infectious clones were generated and used to assess the phenotype of viral infection in the presence or absence of the alphasatellite in tomato, E. heterophylla, Nicotiana benthamiana, Arabidopsis thaliana and Crotalaria juncea. Phenotypic differences of EuYMV infection in the presence or absence of EuYMA were observed in A. thaliana, N. benthamiana and E. heterophylla. Symptoms were more severe when EuYMV was inoculated in combination with EuYMA in N. benthamiana and E. heterophylla, and the presence of the alphasatellite was determinant for symptom development in A. thaliana. Quantification of EuYMV and EuYMA indicated that EuYMA affects the accumulation of EuYMV during infection on a host-dependent basis. Transmission assays indicated that EuYMA negatively affects the transmission of EuYMV by Bemisia tabaci MEAM1. Together, these results indicate that EuYMA is capable of modulating symptoms, viral accumulation and whitefly transmission of EuYMV, potentially interfering with virus dissemination in the field.
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Affiliation(s)
- Talita Bernardon Mar
- Dep de Fitopatologia/BIOAGRO, Universidade Federal de Viçosa, Viçosa, MG 36570-900, Brazil.,National Research Institute for Plant-Pest Interactions, Universidade Federal de Viçosa, Viçosa, MG 36570-900, Brazil
| | - Igor Rodrigues Mendes
- Dep de Fitopatologia/BIOAGRO, Universidade Federal de Viçosa, Viçosa, MG 36570-900, Brazil.,National Research Institute for Plant-Pest Interactions, Universidade Federal de Viçosa, Viçosa, MG 36570-900, Brazil
| | - Douglas Lau
- Embrapa Trigo, Rodovia BR-285, CP 3081, Passo Fundo, RS, 99001-970, Brazil
| | - Elvira Fiallo-Olivé
- National Research Institute for Plant-Pest Interactions, Universidade Federal de Viçosa, Viçosa, MG 36570-900, Brazil.,Instituto de Hortofruticultura Subtropical y Mediterránea ''La Mayora'', Universidad de Málaga - Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Estación Experimental ''La Mayora'', 29750 Algarrobo-Costa, Málaga, Spain
| | - Jesús Navas-Castillo
- National Research Institute for Plant-Pest Interactions, Universidade Federal de Viçosa, Viçosa, MG 36570-900, Brazil.,Instituto de Hortofruticultura Subtropical y Mediterránea ''La Mayora'', Universidad de Málaga - Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Estación Experimental ''La Mayora'', 29750 Algarrobo-Costa, Málaga, Spain
| | - Murilo Siqueira Alves
- Dep de Fitopatologia/BIOAGRO, Universidade Federal de Viçosa, Viçosa, MG 36570-900, Brazil.,National Research Institute for Plant-Pest Interactions, Universidade Federal de Viçosa, Viçosa, MG 36570-900, Brazil
| | - F Murilo Zerbini
- Dep de Fitopatologia/BIOAGRO, Universidade Federal de Viçosa, Viçosa, MG 36570-900, Brazil.,National Research Institute for Plant-Pest Interactions, Universidade Federal de Viçosa, Viçosa, MG 36570-900, Brazil
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109
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Ju Z, Cao D, Gao C, Zuo J, Zhai B, Li S, Zhu H, Fu D, Luo Y, Zhu B. A Viral Satellite DNA Vector (TYLCCNV) for Functional Analysis of miRNAs and siRNAs in Plants. PLANT PHYSIOLOGY 2017; 173:1940-1952. [PMID: 28228536 PMCID: PMC5373046 DOI: 10.1104/pp.16.01489] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Accepted: 02/19/2017] [Indexed: 05/11/2023]
Abstract
With experimental and bioinformatical methods, numerous small RNAs, including microRNAs (miRNAs) and short interfering RNAs (siRNAs), have been found in plants, and they play vital roles in various biological regulation processes. However, most of these small RNAs remain to be functionally characterized. Until now, only several viral vectors were developed to overexpress miRNAs with limited application in plants. In this study, we report a new small RNA overexpression system via viral satellite DNA associated with Tomato yellow leaf curl China virus (TYLCCNV) vector, which could highly overexpress not only artificial and endogenous miRNAs but also endogenous siRNAs in Nicotiana benthamiana First, we constructed basic TYLCCNV-amiRPDS(319L) vector with widely used AtMIR319a backbone, but the expected photobleaching phenotype was very weak. Second, through comparing the effect of backbones (AtMIR319a, AtMIR390a, and SlMIR159) on specificity and significance of generating small RNAs, the AtMIR390a backbone was optimally selected to construct the small RNA overexpression system. Third, through sRNA-Seq and Degradome-Seq, the small RNAs from AtMIR390a backbone in TYLCCNV-amiRPDS(390) vector were confirmed to highly overexpress amiRPDS and specifically silence targeted PDS gene. Using this system, rapid functional analysis of endogenous miRNAs and siRNAs was carried out, including miR156 and athTAS3a 5'D8(+). Meanwhile, through designing corresponding artificial miRNAs, this system could also significantly silence targeted endogenous genes and show specific phenotypes, including PDS, Su, and PCNA These results demonstrated that this small RNA overexpression system could contribute to investigating not only the function of endogenous small RNAs, but also the functional genes in plants.
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Affiliation(s)
- Zheng Ju
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China (Z.J., D.C., Ba.Z., S.L., H.Z., D.F., Y.L., Be.Z.)
- Biotechnology Research Center, Shandong Academy of Agricultural Sciences, Jinan 250100, China (C.G.); and
- National Engineering Research Center for Vegetables, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China (J.Z.)
| | - Dongyan Cao
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China (Z.J., D.C., Ba.Z., S.L., H.Z., D.F., Y.L., Be.Z.)
- Biotechnology Research Center, Shandong Academy of Agricultural Sciences, Jinan 250100, China (C.G.); and
- National Engineering Research Center for Vegetables, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China (J.Z.)
| | - Chao Gao
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China (Z.J., D.C., Ba.Z., S.L., H.Z., D.F., Y.L., Be.Z.)
- Biotechnology Research Center, Shandong Academy of Agricultural Sciences, Jinan 250100, China (C.G.); and
- National Engineering Research Center for Vegetables, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China (J.Z.)
| | - Jinhua Zuo
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China (Z.J., D.C., Ba.Z., S.L., H.Z., D.F., Y.L., Be.Z.)
- Biotechnology Research Center, Shandong Academy of Agricultural Sciences, Jinan 250100, China (C.G.); and
- National Engineering Research Center for Vegetables, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China (J.Z.)
| | - Baiqiang Zhai
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China (Z.J., D.C., Ba.Z., S.L., H.Z., D.F., Y.L., Be.Z.)
- Biotechnology Research Center, Shandong Academy of Agricultural Sciences, Jinan 250100, China (C.G.); and
- National Engineering Research Center for Vegetables, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China (J.Z.)
| | - Shan Li
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China (Z.J., D.C., Ba.Z., S.L., H.Z., D.F., Y.L., Be.Z.)
- Biotechnology Research Center, Shandong Academy of Agricultural Sciences, Jinan 250100, China (C.G.); and
- National Engineering Research Center for Vegetables, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China (J.Z.)
| | - Hongliang Zhu
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China (Z.J., D.C., Ba.Z., S.L., H.Z., D.F., Y.L., Be.Z.)
- Biotechnology Research Center, Shandong Academy of Agricultural Sciences, Jinan 250100, China (C.G.); and
- National Engineering Research Center for Vegetables, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China (J.Z.)
| | - Daqi Fu
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China (Z.J., D.C., Ba.Z., S.L., H.Z., D.F., Y.L., Be.Z.)
- Biotechnology Research Center, Shandong Academy of Agricultural Sciences, Jinan 250100, China (C.G.); and
- National Engineering Research Center for Vegetables, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China (J.Z.)
| | - Yunbo Luo
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China (Z.J., D.C., Ba.Z., S.L., H.Z., D.F., Y.L., Be.Z.)
- Biotechnology Research Center, Shandong Academy of Agricultural Sciences, Jinan 250100, China (C.G.); and
- National Engineering Research Center for Vegetables, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China (J.Z.)
| | - Benzhong Zhu
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China (Z.J., D.C., Ba.Z., S.L., H.Z., D.F., Y.L., Be.Z.);
- Biotechnology Research Center, Shandong Academy of Agricultural Sciences, Jinan 250100, China (C.G.); and
- National Engineering Research Center for Vegetables, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China (J.Z.)
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Li F, Zhao N, Li Z, Xu X, Wang Y, Yang X, Liu SS, Wang A, Zhou X. A calmodulin-like protein suppresses RNA silencing and promotes geminivirus infection by degrading SGS3 via the autophagy pathway in Nicotiana benthamiana. PLoS Pathog 2017; 13:e1006213. [PMID: 28212430 PMCID: PMC5333915 DOI: 10.1371/journal.ppat.1006213] [Citation(s) in RCA: 104] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Revised: 03/02/2017] [Accepted: 02/02/2017] [Indexed: 12/31/2022] Open
Abstract
A recently characterized calmodulin-like protein is an endogenous RNA silencing suppressor that suppresses sense-RNA induced post-transcriptional gene silencing (S-PTGS) and enhances virus infection, but the mechanism underlying calmodulin-like protein-mediated S-PTGS suppression is obscure. Here, we show that a calmodulin-like protein from Nicotiana benthamiana (NbCaM) interacts with Suppressor of Gene Silencing 3 (NbSGS3). Deletion analyses showed that domains essential for the interaction between NbSGS3 and NbCaM are also required for the subcellular localization of NbSGS3 and NbCaM suppressor activity. Overexpression of NbCaM reduced the number of NbSGS3-associated granules by degrading NbSGS3 protein accumulation in the cytoplasm. This NbCaM-mediated NbSGS3 degradation was sensitive to the autophagy inhibitors 3-methyladenine and E64d, and was compromised when key autophagy genes of the phosphatidylinositol 3-kinase (PI3K) complex were knocked down. Meanwhile, silencing of key autophagy genes within the PI3K complex inhibited geminivirus infection. Taken together these data suggest that NbCaM acts as a suppressor of RNA silencing by degrading NbSGS3 through the autophagy pathway.
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Affiliation(s)
- Fangfang Li
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, Zhejiang, China
| | - Nan Zhao
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, Zhejiang, China
| | - Zhenghe Li
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, Zhejiang, China
| | - Xiongbiao Xu
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, Zhejiang, China
| | - Yaqin Wang
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, Zhejiang, China
| | - Xiuling Yang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Shu-Sheng Liu
- Ministry of Agriculture Key Laboratory of Agricultural Entomology, Institute of Insect Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Aiming Wang
- Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, London, Ontario, Canada
| | - Xueping Zhou
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, Zhejiang, China
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111
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Zhong X, Wang ZQ, Xiao R, Wang Y, Xie Y, Zhou X. iTRAQ analysis of the tobacco leaf proteome reveals that RNA-directed DNA methylation (RdDM) has important roles in defense against geminivirus-betasatellite infection. J Proteomics 2017; 152:88-101. [PMID: 27989946 DOI: 10.1016/j.jprot.2016.10.015] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 10/10/2016] [Accepted: 10/27/2016] [Indexed: 11/22/2022]
Abstract
Geminiviruses have caused serious losses in crop production. To investigate the mechanisms underlying host defenses against geminiviruses, an isobaric tags for relative and absolute quantification (iTRAQ)-based quantitative proteomic approach was used to explore the expression profiles of proteins in Nicotiana benthamiana (N. benthamiana) leaves in response to tomato yellow leaf curl China virus (TYLCCNV) with its betasatellite (TYLCCNB) at an early phase. In total, 4155 proteins were identified and 272 proteins were changed differentially in response to TYLCCNV/TYLCCNB infection. Bioinformatics analysis indicated that S-adenosyl-l-methionine cycle II was the most significantly up-regulated biochemical process during TYLCCNV/TYLCCNB infection. The mRNA levels of three proteins in S-adenosyl-l-methionine cycle II were further analyzed by qPCR, each was found significantly up-regulated in TYLCCNV/TYLCCNB-infected N. benthamiana. This result suggested a strong promotion of the biosynthesis of available methyl groups during geminivirus infections. We further tested the potential role of RdDM in N. benthamiana by virus-induced gene silencing (VIGS) and found that a disruption in RdDM resulted in more severe infectious symptoms and higher accumulation of viral DNA after TYLCCNV/TYLCCNB infection. Although the precise functions of these proteins still need to be determined, our proteomic results enhance the understanding of plant antiviral mechanisms. BIOLOGICAL SIGNIFICANCE One of the major limitations to crop growth in the worldwide is the prevalence of geminiviruses. They are able to infect food and cash crops and cause serious crop failures and economic losses worldwide, especially in Africa and Asia. Tomato yellow leaf curl China virus (TYLCCNV), which causes severe viral diseases in China, is a monopartite geminivirus associated with the betasatellite (TYLCCNB). However, the mechanisms underlying the TYLCCNV/TYLCCNB defense in plants are still not fully understood at the molecular level. In this study, the combined proteomic, bioinformatic and VIGS analyses revealed that TYLCCNV/TYLCCNB invasion caused complex proteomic alterations in the leaves of N. benthamiana involving the processes of stress and defense, energy production, photosynthesis, protein homeostasis, metabolism, cell structure, signal transduction, transcription, transportation, and cell growth/division. Promotion of available methyl groups via the S-adenosyl-l-methionine cycle II pathway in N. benthamiana appeared crucial for antiviral responses. These findings enhance our understanding in the proteomic aspects of host antiviral defenses against geminiviruses, and also demonstrate that the combination of proteomics with bioinformatics and VIGS analysis is an effective approach to investigate systemic plant responses to geminiviruses and to shed light on plant-virus interactions.
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Affiliation(s)
- Xueting Zhong
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China.
| | - Zhan Qi Wang
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China.
| | - Ruyuan Xiao
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China.
| | - Yaqin Wang
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China.
| | - Yan Xie
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China.
| | - Xueping Zhou
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China; State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
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112
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Wang Q, Zhang C, Wang C, Qian Y, Li Z, Hong J, Zhou X. Further characterization of Maize chlorotic mottle virus and its synergistic interaction with Sugarcane mosaic virus in maize. Sci Rep 2017; 7:39960. [PMID: 28059116 PMCID: PMC5216416 DOI: 10.1038/srep39960] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 11/30/2016] [Indexed: 01/24/2023] Open
Abstract
Maize chlorotic mottle virus (MCMV) was first reported in maize in China in 2009. In this study we further analyzed the epidemiology of MCMV and corn lethal necrosis disease (CLND) in China. We determined that CLND observed in China was caused by co-infection of MCMV and sugarcane mosaic virus (SCMV). Phylogenetic analysis using four full-length MCMV cDNA sequences obtained in this study and the available MCMV sequences retrieved from GenBank indicated that Chinese MCMV isolates were derived from the same source. To screen for maize germplasm resistance against MCMV infection, we constructed an infectious clone of MCMV isolate YN2 (pMCMV) and developed an Agrobacterium-mediated injection procedure to allow high throughput inoculations of maize with the MCMV infectious clone. Electron microscopy showed that chloroplast photosynthesis in leaves was significantly impeded by the co-infection of MCMV and SCMV. Mitochondria in the MCMV and SCMV co-infected cells were more severely damaged than in MCMV-infected cells. The results of this study provide further insight into the epidemiology of MCMV in China and shed new light on physiological and cytopathological changes related to CLND in maize.
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Affiliation(s)
- Qiang Wang
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou 310029, People’s Republic of China
| | - Chao Zhang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, People’s Republic of China
| | - Chunyan Wang
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou 310029, People’s Republic of China
| | - Yajuan Qian
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou 310029, People’s Republic of China
| | - Zhenghe Li
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou 310029, People’s Republic of China
| | - Jian Hong
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou 310029, People’s Republic of China
| | - Xueping Zhou
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, People’s Republic of China
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou 310029, People’s Republic of China
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113
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Mäkinen K, Lõhmus A, Pollari M. Plant RNA Regulatory Network and RNA Granules in Virus Infection. FRONTIERS IN PLANT SCIENCE 2017; 8:2093. [PMID: 29312371 PMCID: PMC5732267 DOI: 10.3389/fpls.2017.02093] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Accepted: 11/24/2017] [Indexed: 05/18/2023]
Abstract
Regulation of post-transcriptional gene expression on mRNA level in eukaryotic cells includes translocation, translation, translational repression, storage, mRNA decay, RNA silencing, and nonsense-mediated decay. These processes are associated with various RNA-binding proteins and cytoplasmic ribonucleoprotein complexes many of which are conserved across eukaryotes. Microscopically visible aggregations formed by ribonucleoprotein complexes are termed RNA granules. Stress granules where the translationally inactive mRNAs are stored and processing bodies where mRNA decay may occur present the most studied RNA granule types. Diverse RNP-granules are increasingly being assigned important roles in viral infections. Although the majority of the molecular level studies on the role of RNA granules in viral translation and replication have been conducted in mammalian systems, some studies link also plant virus infection to RNA granules. An increasing body of evidence indicates that plant viruses require components of stress granules and processing bodies for their replication and translation, but how extensively the cellular mRNA regulatory network is utilized by plant viruses has remained largely enigmatic. Antiviral RNA silencing, which is an important regulator of viral RNA stability and expression in plants, is commonly counteracted by viral suppressors of RNA silencing. Some of the RNA silencing suppressors localize to cellular RNA granules and have been proposed to carry out their suppression functions there. Moreover, plant nucleotide-binding leucine-rich repeat protein-mediated virus resistance has been linked to enhanced processing body formation and translational repression of viral RNA. Many interesting questions relate to how the pathways of antiviral RNA silencing leading to viral RNA degradation and/or repression of translation, suppression of RNA silencing and viral RNA translation converge in plants and how different RNA granules and their individual components contribute to these processes. In this review we discuss the roles of cellular RNA regulatory mechanisms and RNA granules in plant virus infection in the light of current knowledge and compare the findings to those made in animal virus studies.
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114
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Makiyama RK, Fernandes CAH, Dreyer TR, Moda BS, Matioli FF, Fontes MRM, Maia IG. Structural and thermodynamic studies of the tobacco calmodulin-like rgs-CaM protein. Int J Biol Macromol 2016; 92:1288-1297. [PMID: 27514444 DOI: 10.1016/j.ijbiomac.2016.08.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 07/08/2016] [Accepted: 08/07/2016] [Indexed: 11/23/2022]
Abstract
The tobacco calmodulin-like protein rgs-CaM is involved in host defense against virus and is reported to possess an associated RNA silencing suppressor activity. Rgs-CaM is also believed to act as an antiviral factor by interacting and targeting viral silencing suppressors for autophagic degradation. Despite these functional data, calcium interplay in the modulation of rgs-CaM is still poorly understood. Here we show that rgs-CaM displays a prevalent alpha-helical conformation and possesses three functional Ca2+-binding sites. Using computational modeling and molecular dynamics simulation, we demonstrate that Ca2+ binding to rgs-CaM triggers expansion of its tertiary structure with reorientation of alpha-helices within the EF-hands. This conformational change leads to the exposure of a large negatively charged region that may be implicated in the electrostatic interactions between rgs-CaM and viral suppressors. Moreover, the kd values obtained for Ca2+ binding to the three functional sites are not within the affinity range of a typical Ca2+ sensor.
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Affiliation(s)
- Rodrigo K Makiyama
- Universidade Estadual Paulista (UNESP), Instituto de Biociências, Departamento de Genética, Botucatu, SP, Brazil
| | - Carlos A H Fernandes
- Universidade Estadual Paulista (UNESP), Instituto de Biociências, Departamento de Física e Biofísica, Botucatu, SP, Brazil
| | - Thiago R Dreyer
- Universidade Estadual Paulista (UNESP), Instituto de Biociências, Departamento de Física e Biofísica, Botucatu, SP, Brazil
| | - Bruno S Moda
- Universidade Estadual Paulista (UNESP), Instituto de Biociências, Departamento de Genética, Botucatu, SP, Brazil
| | - Fabio F Matioli
- Universidade Estadual Paulista (UNESP), Instituto de Biociências, Departamento de Física e Biofísica, Botucatu, SP, Brazil
| | - Marcos R M Fontes
- Universidade Estadual Paulista (UNESP), Instituto de Biociências, Departamento de Física e Biofísica, Botucatu, SP, Brazil
| | - Ivan G Maia
- Universidade Estadual Paulista (UNESP), Instituto de Biociências, Departamento de Genética, Botucatu, SP, Brazil.
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115
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Palma-Martínez I, Guerrero-Mandujano A, Ruiz-Ruiz MJ, Hernández-Cortez C, Molina-López J, Bocanegra-García V, Castro-Escarpulli G. Active Shiga-Like Toxin Produced by Some Aeromonas spp., Isolated in Mexico City. Front Microbiol 2016; 7:1552. [PMID: 27757103 PMCID: PMC5048074 DOI: 10.3389/fmicb.2016.01552] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 09/16/2016] [Indexed: 12/29/2022] Open
Abstract
RNA silencing is a conserved mechanism that utilizes small RNAs (sRNAs) to direct the regulation of gene expression at the transcriptional or post-transcriptional level. Plants utilizing RNA silencing machinery to defend pathogen infection was first identified in plant–virus interaction and later was observed in distinct plant–pathogen interactions. RNA silencing is not only responsible for suppressing RNA accumulation and movement of virus and viroid, but also facilitates plant immune responses against bacterial, oomycete, and fungal infection. Interestingly, even the same plant sRNA can perform different roles when encounters with different pathogens. On the other side, pathogens counteract by generating sRNAs that directly regulate pathogen gene expression to increase virulence or target host genes to facilitate pathogen infection. Here, we summarize the current knowledge of the characterization and biogenesis of host- and pathogen-derived sRNAs, as well as the different RNA silencing machineries that plants utilize to defend against different pathogens. The functions of these sRNAs in defense and counter-defense and their mechanisms for regulation during different plant–pathogen interactions are also discussed.
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Affiliation(s)
- Ingrid Palma-Martínez
- Laboratorio de Bacteriología Médica, Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional Mexico City, Mexico
| | - Andrea Guerrero-Mandujano
- Laboratorio de Bacteriología Médica, Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional Mexico City, Mexico
| | - Manuel J Ruiz-Ruiz
- Laboratorio de Bacteriología Médica, Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico NacionalMexico City, Mexico; Laboratorio Central de Análisis Clínicos Unidad Médica de Alta Especialidad Hospital de Pediatría "Silvestre Frenk Freund," Centro Médico Nacional Siglo XXIMexico City, Mexico
| | - Cecilia Hernández-Cortez
- Laboratorio de Bacteriología Médica, Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico NacionalMexico City, Mexico; Laboratorio de Bioquímica Microbiana, Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico NacionalMexico City, Mexico
| | - José Molina-López
- Departamento de Salud Pública, Facultad de Medicina, Universidad Nacional Autónoma de México Mexico City, Mexico
| | | | - Graciela Castro-Escarpulli
- Laboratorio de Bacteriología Médica, Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional Mexico City, Mexico
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116
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Fang YY, Zhao JH, Liu SW, Wang S, Duan CG, Guo HS. CMV2b-AGO Interaction Is Required for the Suppression of RDR-Dependent Antiviral Silencing in Arabidopsis. Front Microbiol 2016; 7:1329. [PMID: 27605926 PMCID: PMC4995204 DOI: 10.3389/fmicb.2016.01329] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Accepted: 08/11/2016] [Indexed: 12/02/2022] Open
Abstract
Using a transient plant system, it was previously found that the suppression of Cucumber mosaic virus (CMV) 2b protein relies on its double-strand (ds) RNA binding capacity, but it is independent of its interaction with ARGONAUTE (AGO) proteins. Thus, the biological meaning of the 2b-AGO interaction in the context of virus infection remains elusive. In this study, we created infectious clones of CMV mutants that expressed the 2b functional domains of dsRNA or AGO binding and tested the effect of these CMV mutants on viral pathogenicity. We found that the mutant CMV2b(1–76) expressing the 2b dsRNA-binding domain exhibited the same virulence as wild-type CMV in infection with either wild-type Arabidopsis or rdr1/6 plants with RDR1- and RDR6-deficient mutations. However, remarkably reduced viral RNA levels and increased virus (v)siRNAs were detected in CMV2b(1–76)-infected Arabidopsis in comparison to CMV infection, which demonstrated that the 2b(1–76) deleted AGO-binding domain failed to suppress the RDR1/RDR6-dependent degradation of viral RNAs. The mutant CMV2b(8–111) expressing mutant 2b, in which the N-terminal 7 amino acid (aa) was deleted, exhibited slightly reduced virulence, but not viral RNA levels, in both wild-type and rdr1/6 plants, which indicated that 2b retained the AGO-binding activity acquired the counter-RDRs degradation of viral RNAs. The deletion of the N-terminal 7 aa of 2b affected virulence due to the reduced affinity for long dsRNA. The mutant CMV2b(18–111) expressing mutant 2b lacked the N-terminal 17 aa but retained its AGO-binding activity greatly reduced virulence and viral RNA level. Together with the instability of both 2b(18–111)-EGFP and RFP-AGO4 proteins when co-expressed in Nicotiana benthamiana leaves, our data demonstrates that the effect of 2b-AGO interaction on counter-RDRs antiviral defense required the presence of 2b dsRNA-binding activity. Taken together, our findings demonstrate that the dsRNA-binding activity of the 2b was essential for virulence, whereas the 2b-AGO interaction was necessary for interference with RDR1/6-dependent antiviral silencing in Arabidopsis.
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Affiliation(s)
- Yuan-Yuan Fang
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences Beijing, China
| | - Jian-Hua Zhao
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences Beijing, China
| | - Shang-Wu Liu
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of SciencesBeijing, China; Virus-free Seedling Research Institute, Heilongjiang Academy of Agricultural SciencesHarbin, China
| | - Sheng Wang
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences Beijing, China
| | - Cheng-Guo Duan
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences Beijing, China
| | - Hui-Shan Guo
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of SciencesBeijing, China; College of Life Sciences, University of Chinese Academy of SciencesBeijing, China
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117
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Jackel JN, Storer JM, Coursey T, Bisaro DM. Arabidopsis RNA Polymerases IV and V Are Required To Establish H3K9 Methylation, but Not Cytosine Methylation, on Geminivirus Chromatin. J Virol 2016. [PMID: 27279611 DOI: 10.1128/jvi.00656-616] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/30/2023] Open
Abstract
UNLABELLED In plants, RNA-directed DNA methylation (RdDM) employs small RNAs to target enzymes that methylate cytosine residues. Cytosine methylation and dimethylation of histone 3 lysine 9 (H3K9me2) are often linked. Together they condition an epigenetic defense that results in chromatin compaction and transcriptional silencing of transposons and viral chromatin. Canonical RdDM (Pol IV-RdDM), involving RNA polymerases IV and V (Pol IV and Pol V), was believed to be necessary to establish cytosine methylation, which in turn could recruit H3K9 methyltransferases. However, recent studies have revealed that a pathway involving Pol II and RNA-dependent RNA polymerase 6 (RDR6) (RDR6-RdDM) is likely responsible for establishing cytosine methylation at naive loci, while Pol IV-RdDM acts to reinforce and maintain it. We used the geminivirus Beet curly top virus (BCTV) as a model to examine the roles of Pol IV and Pol V in establishing repressive viral chromatin methylation. As geminivirus chromatin is formed de novo in infected cells, these viruses are unique models for processes involved in the establishment of epigenetic marks. We confirm that Pol IV and Pol V are not needed to establish viral DNA methylation but are essential for its amplification. Remarkably, however, both Pol IV and Pol V are required for deposition of H3K9me2 on viral chromatin. Our findings suggest that cytosine methylation alone is not sufficient to trigger de novo deposition of H3K9me2 and further that Pol IV-RdDM is responsible for recruiting H3K9 methyltransferases to viral chromatin. IMPORTANCE In plants, RNA-directed DNA methylation (RdDM) uses small RNAs to target cytosine methylation, which is often linked to H3K9me2. These epigenetic marks silence transposable elements and DNA virus genomes, but how they are established is not well understood. Canonical RdDM, involving Pol IV and Pol V, was thought to establish cytosine methylation that in turn could recruit H3K9 methyltransferases, but recent studies compel a reevaluation of this view. We used BCTV to investigate the roles of Pol IV and Pol V in chromatin methylation. We found that both are needed to amplify, but not to establish, DNA methylation. However, both are required for deposition of H3K9me2. Our findings suggest that cytosine methylation is not sufficient to recruit H3K9 methyltransferases to naive viral chromatin and further that Pol IV-RdDM is responsible.
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Affiliation(s)
- Jamie N Jackel
- Department of Molecular Genetics, Center for Applied Plant Sciences, Center for RNA Biology, and Graduate Program in Molecular, Cellular, and Developmental Biology, The Ohio State University, Columbus, Ohio, USA
| | - Jessica M Storer
- Department of Molecular Genetics, Center for Applied Plant Sciences, Center for RNA Biology, and Graduate Program in Molecular, Cellular, and Developmental Biology, The Ohio State University, Columbus, Ohio, USA
| | - Tami Coursey
- Department of Molecular Genetics, Center for Applied Plant Sciences, Center for RNA Biology, and Graduate Program in Molecular, Cellular, and Developmental Biology, The Ohio State University, Columbus, Ohio, USA
| | - David M Bisaro
- Department of Molecular Genetics, Center for Applied Plant Sciences, Center for RNA Biology, and Graduate Program in Molecular, Cellular, and Developmental Biology, The Ohio State University, Columbus, Ohio, USA
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118
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Arabidopsis RNA Polymerases IV and V Are Required To Establish H3K9 Methylation, but Not Cytosine Methylation, on Geminivirus Chromatin. J Virol 2016; 90:7529-7540. [PMID: 27279611 DOI: 10.1128/jvi.00656-16] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 06/01/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED In plants, RNA-directed DNA methylation (RdDM) employs small RNAs to target enzymes that methylate cytosine residues. Cytosine methylation and dimethylation of histone 3 lysine 9 (H3K9me2) are often linked. Together they condition an epigenetic defense that results in chromatin compaction and transcriptional silencing of transposons and viral chromatin. Canonical RdDM (Pol IV-RdDM), involving RNA polymerases IV and V (Pol IV and Pol V), was believed to be necessary to establish cytosine methylation, which in turn could recruit H3K9 methyltransferases. However, recent studies have revealed that a pathway involving Pol II and RNA-dependent RNA polymerase 6 (RDR6) (RDR6-RdDM) is likely responsible for establishing cytosine methylation at naive loci, while Pol IV-RdDM acts to reinforce and maintain it. We used the geminivirus Beet curly top virus (BCTV) as a model to examine the roles of Pol IV and Pol V in establishing repressive viral chromatin methylation. As geminivirus chromatin is formed de novo in infected cells, these viruses are unique models for processes involved in the establishment of epigenetic marks. We confirm that Pol IV and Pol V are not needed to establish viral DNA methylation but are essential for its amplification. Remarkably, however, both Pol IV and Pol V are required for deposition of H3K9me2 on viral chromatin. Our findings suggest that cytosine methylation alone is not sufficient to trigger de novo deposition of H3K9me2 and further that Pol IV-RdDM is responsible for recruiting H3K9 methyltransferases to viral chromatin. IMPORTANCE In plants, RNA-directed DNA methylation (RdDM) uses small RNAs to target cytosine methylation, which is often linked to H3K9me2. These epigenetic marks silence transposable elements and DNA virus genomes, but how they are established is not well understood. Canonical RdDM, involving Pol IV and Pol V, was thought to establish cytosine methylation that in turn could recruit H3K9 methyltransferases, but recent studies compel a reevaluation of this view. We used BCTV to investigate the roles of Pol IV and Pol V in chromatin methylation. We found that both are needed to amplify, but not to establish, DNA methylation. However, both are required for deposition of H3K9me2. Our findings suggest that cytosine methylation is not sufficient to recruit H3K9 methyltransferases to naive viral chromatin and further that Pol IV-RdDM is responsible.
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Hedil M, Kormelink R. Viral RNA Silencing Suppression: The Enigma of Bunyavirus NSs Proteins. Viruses 2016; 8:v8070208. [PMID: 27455310 PMCID: PMC4974542 DOI: 10.3390/v8070208] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Revised: 07/18/2016] [Accepted: 07/19/2016] [Indexed: 12/21/2022] Open
Abstract
The Bunyaviridae is a family of arboviruses including both plant- and vertebrate-infecting representatives. The Tospovirus genus accommodates plant-infecting bunyaviruses, which not only replicate in their plant host, but also in their insect thrips vector during persistent propagative transmission. For this reason, they are generally assumed to encounter antiviral RNA silencing in plants and insects. Here we present an overview on how tospovirus nonstructural NSs protein counteracts antiviral RNA silencing in plants and what is known so far in insects. Like tospoviruses, members of the related vertebrate-infecting bunyaviruses classified in the genera Orthobunyavirus, Hantavirus and Phlebovirus also code for a NSs protein. However, for none of them RNA silencing suppressor activity has been unambiguously demonstrated in neither vertebrate host nor arthropod vector. The second part of this review will briefly describe the role of these NSs proteins in modulation of innate immune responses in mammals and elaborate on a hypothetical scenario to explain if and how NSs proteins from vertebrate-infecting bunyaviruses affect RNA silencing. If so, why this discovery has been hampered so far.
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Affiliation(s)
- Marcio Hedil
- Laboratory of Virology, Department of Plant Sciences, Wageningen University, Wageningen, 6708PB, The Netherlands.
| | - Richard Kormelink
- Laboratory of Virology, Department of Plant Sciences, Wageningen University, Wageningen, 6708PB, The Netherlands.
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Shen Q, Hu T, Bao M, Cao L, Zhang H, Song F, Xie Q, Zhou X. Tobacco RING E3 Ligase NtRFP1 Mediates Ubiquitination and Proteasomal Degradation of a Geminivirus-Encoded βC1. MOLECULAR PLANT 2016; 9:911-25. [PMID: 27018391 DOI: 10.1016/j.molp.2016.03.008] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Revised: 02/17/2016] [Accepted: 03/03/2016] [Indexed: 05/19/2023]
Abstract
The βC1 protein encoded by the Tomato yellow leaf curl China virus-associated betasatellite functions as a pathogenicity determinant. To better understand the molecular basis whereby βC1 functions in pathogenicity, a yeast two-hybrid screen of a tobacco cDNA library was carried out using βC1 as the bait. The screen revealed that βC1 interacts with a tobacco RING-finger protein designated NtRFP1, which was further confirmed by the bimolecular fluorescence complementation and co-immunoprecipitation assays in Nicotiana benthamiana cells. Expression of NtRFP1 was induced by βC1, and in vitro ubiquitination assays showed that NtRFP1 is a functional E3 ubiquitin ligase that mediates βC1 ubiquitination. In addition, βC1 was shown to be ubiquitinated in vivo and degraded by the plant 26S proteasome. After viral infection, plants overexpressing NtRFP1 developed attenuated symptoms, whereas plants with silenced expression of NtRFP1 showed severe symptoms. Other lines of evidence showed that NtRFP1 attenuates βC1-induced symptoms through promoting its degradation by the 26S proteasome. Taken together, our results suggest that tobacco RING E3 ligase NtRFP1 attenuates disease symptoms by interacting with βC1 to mediate its ubiquitination and degradation via the ubiquitin/26S proteasome system.
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Affiliation(s)
- Qingtang Shen
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Tao Hu
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Min Bao
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China; State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Linge Cao
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Huawei Zhang
- State Key Laboratory of Plant Genomics, National Center for Plant Gene Research, Chinese Academy of Sciences, Beijing 100101, China
| | - Fengmin Song
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Qi Xie
- State Key Laboratory of Plant Genomics, National Center for Plant Gene Research, Chinese Academy of Sciences, Beijing 100101, China
| | - Xueping Zhou
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China; State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
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Nath A, Subbiah K. Probing an optimal class distribution for enhancing prediction and feature characterization of plant virus-encoded RNA-silencing suppressors. 3 Biotech 2016; 6:93. [PMID: 28330163 PMCID: PMC4801844 DOI: 10.1007/s13205-016-0410-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Accepted: 03/03/2016] [Indexed: 10/28/2022] Open
Abstract
To counter the host RNA silencing defense mechanism, many plant viruses encode RNA silencing suppressor proteins. These groups of proteins share very low sequence and structural similarities among them, which consequently hamper their annotation using sequence similarity-based search methods. Alternatively the machine learning-based methods can become a suitable choice, but the optimal performance through machine learning-based methods is being affected by various factors such as class imbalance, incomplete learning, selection of inappropriate features, etc. In this paper, we have proposed a novel approach to deal with the class imbalance problem by finding the optimal class distribution for enhancing the prediction accuracy for the RNA silencing suppressors. The optimal class distribution was obtained using different resampling techniques with varying degrees of class distribution starting from natural distribution to ideal distribution, i.e., equal distribution. The experimental results support the fact that optimal class distribution plays an important role to achieve near perfect learning. The best prediction results are obtained with Sequential Minimal Optimization (SMO) learning algorithm. We could achieve a sensitivity of 98.5 %, specificity of 92.6 % with an overall accuracy of 95.3 % on a tenfold cross validation and is further validated using leave one out cross validation test. It was also observed that the machine learning models trained on oversampled training sets using synthetic minority oversampling technique (SMOTE) have relatively performed better than on both randomly undersampled and imbalanced training data sets. Further, we have characterized the important discriminatory sequence features of RNA-silencing suppressors which distinguish these groups of proteins from other protein families.
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Jia Q, Liu N, Xie K, Dai Y, Han S, Zhao X, Qian L, Wang Y, Zhao J, Gorovits R, Xie D, Hong Y, Liu Y. CLCuMuB βC1 Subverts Ubiquitination by Interacting with NbSKP1s to Enhance Geminivirus Infection in Nicotiana benthamiana. PLoS Pathog 2016; 12:e1005668. [PMID: 27315204 PMCID: PMC4912122 DOI: 10.1371/journal.ppat.1005668] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Accepted: 05/10/2016] [Indexed: 11/21/2022] Open
Abstract
Viruses interfere with and usurp host machinery and circumvent defense responses to create a suitable cellular environment for successful infection. This is usually achieved through interactions between viral proteins and host factors. Geminiviruses are a group of plant-infecting DNA viruses, of which some contain a betasatellite, known as DNAβ. Here, we report that Cotton leaf curl Multan virus (CLCuMuV) uses its sole satellite-encoded protein βC1 to regulate the plant ubiquitination pathway for effective infection. We found that CLCuMu betasatellite (CLCuMuB) βC1 interacts with NbSKP1, and interrupts the interaction of NbSKP1s with NbCUL1. Silencing of either NbSKP1s or NbCUL1 enhances the accumulation of CLCuMuV genomic DNA and results in severe disease symptoms in plants. βC1 impairs the integrity of SCFCOI1 and the stabilization of GAI, a substrate of the SCFSYL1 to hinder responses to jasmonates (JA) and gibberellins (GA). Moreover, JA treatment reduces viral accumulation and symptoms. These results suggest that CLCuMuB βC1 inhibits the ubiquitination function of SCF E3 ligases through interacting with NbSKP1s to enhance CLCuMuV infection and symptom induction in plants.
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Affiliation(s)
- Qi Jia
- MOE Key Laboratory of Bioinformatics, Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Na Liu
- MOE Key Laboratory of Bioinformatics, Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Ke Xie
- MOE Key Laboratory of Bioinformatics, Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Yanwan Dai
- MOE Key Laboratory of Bioinformatics, Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China
- College of Biological Sciences, China Agricultural University, Beijing, China
| | - Shaojie Han
- MOE Key Laboratory of Bioinformatics, Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Xijuan Zhao
- MOE Key Laboratory of Bioinformatics, Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Lichao Qian
- MOE Key Laboratory of Bioinformatics, Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Yunjing Wang
- MOE Key Laboratory of Bioinformatics, Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Jinping Zhao
- MOE Key Laboratory of Bioinformatics, Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China
- Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
| | - Rena Gorovits
- Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot, Israel
| | - Daoxin Xie
- MOE Key Laboratory of Bioinformatics, Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Yiguo Hong
- Research Centre for Plant RNA Signaling, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Yule Liu
- MOE Key Laboratory of Bioinformatics, Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China
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Huang J, Yang M, Zhang X. The function of small RNAs in plant biotic stress response. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2016; 58:312-27. [PMID: 26748943 DOI: 10.1111/jipb.12463] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 01/07/2016] [Indexed: 05/18/2023]
Abstract
Small RNAs (sRNAs) play essential roles in plants upon biotic stress. Plants utilize RNA silencing machinery to facilitate pathogen-associated molecular pattern-triggered immunity and effector-triggered immunity to defend against pathogen attack or to facilitate defense against insect herbivores. Pathogens, on the other hand, are also able to generate effectors and sRNAs to counter the host immune response. The arms race between plants and pathogens/insect herbivores has triggered the evolution of sRNAs, RNA silencing machinery and pathogen effectors. A great number of studies have been performed to investigate the roles of sRNAs in plant defense, bringing in the opportunity to utilize sRNAs in plant protection. Transgenic plants with pathogen-derived resistance ability or transgenerational defense have been generated, which show promising potential as solutions for pathogen/insect herbivore problems in the field. Here we summarize the recent progress on the function of sRNAs in response to biotic stress, mainly in plant-pathogen/insect herbivore interaction, and the application of sRNAs in disease and insect herbivore control.
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Affiliation(s)
- Juan Huang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Meiling Yang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Xiaoming Zhang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
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Zhang T, Xu X, Huang C, Qian Y, Li Z, Zhou X. A Novel DNA Motif Contributes to Selective Replication of a Geminivirus-Associated Betasatellite by a Helper Virus-Encoded Replication-Related Protein. J Virol 2016; 90:2077-89. [PMID: 26656709 PMCID: PMC4734014 DOI: 10.1128/jvi.02290-15] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 12/02/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Rolling-circle replication of single-stranded genomes of plant geminiviruses is initiated by sequence-specific DNA binding of the viral replication-related protein (Rep) to its cognate genome at the replication origin. Monopartite begomovirus-associated betasatellites can be trans replicated by both cognate and some noncognate helper viruses, but the molecular basis of replication promiscuity of betasatellites remains uncharacterized. Earlier studies showed that when tomato yellow leaf curl China virus (TYLCCNV) or tobacco curly shoot virus (TbCSV) is coinoculated with both cognate and noncognate betasatellites, the cognate betasatellite dominates over the noncognate one at the late stages of infection. In this study, we constructed reciprocal chimeric betasatellites between tomato yellow leaf curl China betasatellite and tobacco curly shoot betasatellite and assayed their competitiveness against wild-type betasatellite when coinoculated with TYLCCNV or TbCSV onto plants. We mapped a region immediately upstream of the conserved rolling-circle cruciform structure of betasatellite origin that confers the cognate Rep-mediated replication advantage over the noncognate satellite. DNase I protection and in vitro binding assays further identified a novel sequence element termed Rep-binding motif (RBM), which specifically binds to the cognate Rep protein and to the noncognate Rep, albeit at lower affinity. Furthermore, we showed that RBM-Rep binding affinity is correlated with betasatellite replication efficiency in protoplasts. Our data suggest that although strict specificity of Rep-mediated replication does not exist, betasatellites have adapted to their cognate Reps for efficient replication during coevolution. IMPORTANCE Begomoviruses are numerous circular DNA viruses that cause devastating diseases of crops worldwide. Monopartite begomoviruses are frequently associated with betasatellites which are essential for induction of typical disease symptoms. Coexistence of two distinct betasatellites with one helper virus is rare in nature. Our previous research showed that begomoviruses can trans replicate cognate betasatellites to higher levels than noncognate ones. However, the molecular mechanisms of betasatellites selective replication remain largely unknown. We investigated the interaction between the begomovirus replication-associated protein and betasatellite DNA. We found that the replication-associated protein specifically binds to a motif in betasatellites, with higher affinity for the cognate motif than the noncognate motif. This preference for cognate motif binding determines the selective replication of betasatellites. We also demonstrated that this motif is essential for betasatellite replication. These findings shed new light on the promiscuous yet selective replication of betasatellites by helper geminiviruses.
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Affiliation(s)
- Tong Zhang
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, People's Republic of China
| | - Xiongbiao Xu
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, People's Republic of China
| | - Changjun Huang
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, People's Republic of China
| | - Yajuan Qian
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, People's Republic of China
| | - Zhenghe Li
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, People's Republic of China
| | - Xueping Zhou
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, People's Republic of China State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, People's Republic of China
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Dong K, Wang Y, Zhang Z, Chai LX, Tong X, Xu J, Li D, Wang XB. Two amino acids near the N-terminus of Cucumber mosaic virus 2b play critical roles in the suppression of RNA silencing and viral infectivity. MOLECULAR PLANT PATHOLOGY 2016; 17:173-83. [PMID: 25893424 PMCID: PMC6638393 DOI: 10.1111/mpp.12270] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Cucumber mosaic virus (CMV) 2b suppresses RNA silencing primarily through the binding of double-stranded RNA (dsRNA) of varying sizes. However, the biologically active form of 2b remains elusive. Here, we demonstrate that the single and double alanine substitution mutants in the N-terminal 15th leucine and 18th methionine of CMV 2b exhibit drastically attenuated virulence in wild-type plants, but are efficiently rescued in mutant plants defective in RNA-dependent RNA polymerase 6 (RDR6) and Dicer-like 4 (DCL4). Moreover, the transgenic plants of 2b, but not 2blm (L15A/M18A), rescue the high infectivity of CMV-Δ2b through the suppression of antiviral silencing. L15A, M18A or both weaken 2b suppressor activity on local and systemic transgene silencing. In contrast with the high affinity of 2b to short and long dsRNAs, 2blm is significantly compromised in 21-bp duplex small interfering RNA (siRNA) binding ability, but maintains a strong affinity for long dsRNAs. In cross-linking assays, 2b can form dimers, tetramers and oligomers after treatment with glutaraldehyde, whereas 2blm only forms dimers, rather than tetramers and oligomers, in vitro. Together, these findings suggest that L15 and M18 of CMV 2b are required for high affinity to ds-siRNAs and oligomerization activity, which are essential for the suppression activity of 2b on antiviral silencing.
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Affiliation(s)
- Kai Dong
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Ying Wang
- Department of Plant Pathology, China Agricultural University, Beijing, 100193, China
| | - Zhen Zhang
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Long-Xiang Chai
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Xin Tong
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Jin Xu
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Dawei Li
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Xian-Bing Wang
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
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The battle for survival between viruses and their host plants. Curr Opin Virol 2016; 17:32-38. [PMID: 26800310 DOI: 10.1016/j.coviro.2015.12.001] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Revised: 12/17/2015] [Accepted: 12/22/2015] [Indexed: 12/21/2022]
Abstract
Evolution has equipped plants with defense mechanisms to counterattack virus infections. However, some viruses have acquired the capacity to escape these defense barriers. In their combats, plants use mechanisms such as antiviral RNA silencing that viruses fight against using silencing-repressors. Plants could also resist by mutating a host factor required by the virus to complete a particular step of its infectious cycle. Another successful mechanism of resistance is the hypersensitive response, where plants engineer R genes that recognize specifically their assailants. The recognition is followed by the triggering of a broad spectrum resistance. New understanding of such resistance mechanisms will probably helps to propose new means to enhance plant resistance against viruses.
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127
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Sun YW, Tee CS, Ma YH, Wang G, Yao XM, Ye J. Attenuation of Histone Methyltransferase KRYPTONITE-mediated transcriptional gene silencing by Geminivirus. Sci Rep 2015; 5:16476. [PMID: 26602265 PMCID: PMC4658475 DOI: 10.1038/srep16476] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 10/06/2015] [Indexed: 01/07/2023] Open
Abstract
Although histone H3K9 methylation has been intensively studied in animals and a model plant Arabidopsis thaliana, little is known about the evolution of the histone methyltransferase and its roles in plant biotic stress response. Here we identified a Nicotiana benthamiana homolog of H3K9 histone methyltransferase KRYPTONITE (NbKYP) and demonstrated its fundamental roles on methylation of plant and virus, beside of leading to the suppression of endogenous gene expression and virus replication. NbKYP and another gene encoding DNA methyltransferase CHROMOMETHYLTRANSFERASE 3 (NbCMT3-1) were further identified as the key components of maintenance of transcriptional gene silencing, a DNA methylation involved anti-virus machinery. All three types of DNA methylations (asymmetric CHH and symmetric CHG/CG) were severely affected in NbKYP-silenced plants, but only severe reduction of CHG methylation found in NbCMT3-1-silenced plants. Attesting to the importance of plant histone H3K9 methylation immunity to virus, the virulence of geminiviruses requires virus-encoded trans-activator AC2 which inhibits the expression of KYP via activation of an EAR-motif-containing transcription repressor RAV2 (RELATED TO ABI3 and VP1). The reduction of KYP was correlated with virulence of various similar geminiviruses. These findings provide a novel mechanism of how virus trans-activates a plant endogenous anti-silencing machinery to gain high virulence.
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Affiliation(s)
- Yan-Wei Sun
- State Key Laboratory of Plant Genomics, Institute of
Microbiology, Chinese Academy of Sciences, Beijing
100101, China
| | - Chuan-Sia Tee
- Temasek Life Sciences Laboratory, National University of
Singapore, Singapore
117604, Singapore
| | - Yong-Huan Ma
- State Key Laboratory of Plant Genomics, Institute of
Microbiology, Chinese Academy of Sciences, Beijing
100101, China
| | - Gang Wang
- Temasek Life Sciences Laboratory, National University of
Singapore, Singapore
117604, Singapore
| | - Xiang-Mei Yao
- State Key Laboratory of Plant Genomics, Institute of
Microbiology, Chinese Academy of Sciences, Beijing
100101, China
| | - Jian Ye
- State Key Laboratory of Plant Genomics, Institute of
Microbiology, Chinese Academy of Sciences, Beijing
100101, China
- Temasek Life Sciences Laboratory, National University of
Singapore, Singapore
117604, Singapore
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Kumar RV, Singh AK, Singh AK, Yadav T, Basu S, Kushwaha N, Chattopadhyay B, Chakraborty S. Complexity of begomovirus and betasatellite populations associated with chilli leaf curl disease in India. J Gen Virol 2015; 96:3143-3158. [PMID: 26251220 DOI: 10.1099/jgv.0.000254] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023] Open
Abstract
Chilli, which encompasses several species in the genus Capsicum, is widely consumed throughout the world. In the Indian subcontinent, production of chilli is constrained due to chilli leaf curl disease (ChiLCD) caused by begomoviruses. Despite the considerable economic consequences of ChiLCD on chilli cultivation in India, there have been scant studies of the genetic diversity and structure of the begomoviruses that cause this disease. Here we report on a comprehensive survey across major chilli-growing regions in India. Analysis of samples collected in the survey indicates that ChiLCD-infected plants are associated with a complex of begomoviruses (including one previously unreported species) with a diverse group of betasatellites found in crops and weeds. The associated betasatellites neither enhanced the accumulation of the begomovirus components nor reduced the incubation period in Nicotiana benthamiana. The ChiLCD-associated begomoviruses induced mild symptoms on Capsicum spp., but both the level of helper virus that accumulated and the severity of symptoms were increased in the presence of cognate betasatellites. Interestingly, most of the begomoviruses were found to be intra-species recombinants. The betasatellites possess high nucleotide variability, and recombination among them was also evident. The nucleotide substitution rates were determined for the AV1 gene of begomoviruses (2.60 × 10- 3 substitutions site- 1 year- 1) and the βC1 gene of betasatellites [chilli leaf curl betasatellite (ChiLCB), 2.57 × 10- 4 substitution site- 1 year- 1; tomato leaf curl Bangladesh betasatellite (ToLCBDB), 5.22 × 10- 4 substitution site- 1 year- 1]. This study underscores the current understanding of Indian ChiLCD-associated begomoviruses and also demonstrates the crucial role of betasatellites in severe disease development in Capsicum spp.
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Affiliation(s)
- R Vinoth Kumar
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi- 110 067, India
| | - Achuit Kumar Singh
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi- 110 067, India
| | - Ashish Kumar Singh
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi- 110 067, India
| | - Tribhuwan Yadav
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi- 110 067, India
- Department of Molecular Biophysics and Biochemistry, School of Medicine, Yale University, USA
| | - Saumik Basu
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi- 110 067, India
- Department of Entomology, University of Nebraska, Lincoln, USA
| | - Nirbhay Kushwaha
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi- 110 067, India
| | - Brotati Chattopadhyay
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi- 110 067, India
| | - Supriya Chakraborty
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi- 110 067, India
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Li F, Wang W, Zhao N, Xiao B, Cao P, Wu X, Ye C, Shen E, Qiu J, Zhu QH, Xie J, Zhou X, Fan L. Regulation of Nicotine Biosynthesis by an Endogenous Target Mimicry of MicroRNA in Tobacco. PLANT PHYSIOLOGY 2015; 169:1062-71. [PMID: 26246450 PMCID: PMC4587456 DOI: 10.1104/pp.15.00649] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 08/03/2015] [Indexed: 05/22/2023]
Abstract
The interaction between noncoding endogenous target mimicry (eTM) and its corresponding microRNA (miRNA) is a newly discovered regulatory mechanism and plays pivotal roles in various biological processes in plants. Tobacco (Nicotiana tabacum) is a model plant for studying secondary metabolite alkaloids, of which nicotine accounts for approximately 90%. In this work, we identified four unique tobacco-specific miRNAs that were predicted to target key genes of the nicotine biosynthesis and catabolism pathways and an eTM, novel tobacco miRNA (nta)-eTMX27, for nta-miRX27 that targets QUINOLINATE PHOSPHORIBOSYLTRANSFERASE2 (QPT2) encoding a quinolinate phosphoribosyltransferase. The expression level of nta-miRX27 was significantly down-regulated, while that of QPT2 and nta-eTMX27 was significantly up-regulated after topping, and consequently, nicotine content increased in the topping-treated plants. The topping-induced down-regulation of nta-miRX27 and up-regulation of QPT2 were only observed in plants with a functional nta-eTMX27 but not in transgenic plants containing an RNA interference construct targeting nta-eTMX27. Our results demonstrated that enhanced nicotine biosynthesis in the topping-treated tobacco plants is achieved by nta-eTMX27-mediated inhibition of the expression and functions of nta-miRX27. To our knowledge, this is the first report about regulation of secondary metabolite biosynthesis by an miRNA-eTM regulatory module in plants.
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Affiliation(s)
- Fangfang Li
- Institute of Crop Science and Research Center for Air Pollution and Health (F.L., W.W., N.Z., C.Y., E.S., J.Q., L.F.) and Institute of Biotechnology (F.L., N.Z., X.Z.), Zhejiang University, Hangzhou 310058, China;Yunnan Academy of Tobacco Agricultural Sciences and China Tobacco Breeding Research Center at Yunnan, Yuxi 653100, China (B.X., X.W.);National Center of Tobacco Genes, Zhengzhou 450001, China (P.C.);Commonwealth Scientific and Industrial Research Organization Agriculture Flagship, Canberra, Australian Capital Territory 2601, Australia (Q.-H.Z.); andDepartment of Pharmaceutical Sciences, North Carolina Central University, Durham, North Carolina 27707 (J.X.)
| | - Weidi Wang
- Institute of Crop Science and Research Center for Air Pollution and Health (F.L., W.W., N.Z., C.Y., E.S., J.Q., L.F.) and Institute of Biotechnology (F.L., N.Z., X.Z.), Zhejiang University, Hangzhou 310058, China;Yunnan Academy of Tobacco Agricultural Sciences and China Tobacco Breeding Research Center at Yunnan, Yuxi 653100, China (B.X., X.W.);National Center of Tobacco Genes, Zhengzhou 450001, China (P.C.);Commonwealth Scientific and Industrial Research Organization Agriculture Flagship, Canberra, Australian Capital Territory 2601, Australia (Q.-H.Z.); andDepartment of Pharmaceutical Sciences, North Carolina Central University, Durham, North Carolina 27707 (J.X.)
| | - Nan Zhao
- Institute of Crop Science and Research Center for Air Pollution and Health (F.L., W.W., N.Z., C.Y., E.S., J.Q., L.F.) and Institute of Biotechnology (F.L., N.Z., X.Z.), Zhejiang University, Hangzhou 310058, China;Yunnan Academy of Tobacco Agricultural Sciences and China Tobacco Breeding Research Center at Yunnan, Yuxi 653100, China (B.X., X.W.);National Center of Tobacco Genes, Zhengzhou 450001, China (P.C.);Commonwealth Scientific and Industrial Research Organization Agriculture Flagship, Canberra, Australian Capital Territory 2601, Australia (Q.-H.Z.); andDepartment of Pharmaceutical Sciences, North Carolina Central University, Durham, North Carolina 27707 (J.X.)
| | - Bingguang Xiao
- Institute of Crop Science and Research Center for Air Pollution and Health (F.L., W.W., N.Z., C.Y., E.S., J.Q., L.F.) and Institute of Biotechnology (F.L., N.Z., X.Z.), Zhejiang University, Hangzhou 310058, China;Yunnan Academy of Tobacco Agricultural Sciences and China Tobacco Breeding Research Center at Yunnan, Yuxi 653100, China (B.X., X.W.);National Center of Tobacco Genes, Zhengzhou 450001, China (P.C.);Commonwealth Scientific and Industrial Research Organization Agriculture Flagship, Canberra, Australian Capital Territory 2601, Australia (Q.-H.Z.); andDepartment of Pharmaceutical Sciences, North Carolina Central University, Durham, North Carolina 27707 (J.X.)
| | - Peijian Cao
- Institute of Crop Science and Research Center for Air Pollution and Health (F.L., W.W., N.Z., C.Y., E.S., J.Q., L.F.) and Institute of Biotechnology (F.L., N.Z., X.Z.), Zhejiang University, Hangzhou 310058, China;Yunnan Academy of Tobacco Agricultural Sciences and China Tobacco Breeding Research Center at Yunnan, Yuxi 653100, China (B.X., X.W.);National Center of Tobacco Genes, Zhengzhou 450001, China (P.C.);Commonwealth Scientific and Industrial Research Organization Agriculture Flagship, Canberra, Australian Capital Territory 2601, Australia (Q.-H.Z.); andDepartment of Pharmaceutical Sciences, North Carolina Central University, Durham, North Carolina 27707 (J.X.)
| | - Xingfu Wu
- Institute of Crop Science and Research Center for Air Pollution and Health (F.L., W.W., N.Z., C.Y., E.S., J.Q., L.F.) and Institute of Biotechnology (F.L., N.Z., X.Z.), Zhejiang University, Hangzhou 310058, China;Yunnan Academy of Tobacco Agricultural Sciences and China Tobacco Breeding Research Center at Yunnan, Yuxi 653100, China (B.X., X.W.);National Center of Tobacco Genes, Zhengzhou 450001, China (P.C.);Commonwealth Scientific and Industrial Research Organization Agriculture Flagship, Canberra, Australian Capital Territory 2601, Australia (Q.-H.Z.); andDepartment of Pharmaceutical Sciences, North Carolina Central University, Durham, North Carolina 27707 (J.X.)
| | - Chuyu Ye
- Institute of Crop Science and Research Center for Air Pollution and Health (F.L., W.W., N.Z., C.Y., E.S., J.Q., L.F.) and Institute of Biotechnology (F.L., N.Z., X.Z.), Zhejiang University, Hangzhou 310058, China;Yunnan Academy of Tobacco Agricultural Sciences and China Tobacco Breeding Research Center at Yunnan, Yuxi 653100, China (B.X., X.W.);National Center of Tobacco Genes, Zhengzhou 450001, China (P.C.);Commonwealth Scientific and Industrial Research Organization Agriculture Flagship, Canberra, Australian Capital Territory 2601, Australia (Q.-H.Z.); andDepartment of Pharmaceutical Sciences, North Carolina Central University, Durham, North Carolina 27707 (J.X.)
| | - Enhui Shen
- Institute of Crop Science and Research Center for Air Pollution and Health (F.L., W.W., N.Z., C.Y., E.S., J.Q., L.F.) and Institute of Biotechnology (F.L., N.Z., X.Z.), Zhejiang University, Hangzhou 310058, China;Yunnan Academy of Tobacco Agricultural Sciences and China Tobacco Breeding Research Center at Yunnan, Yuxi 653100, China (B.X., X.W.);National Center of Tobacco Genes, Zhengzhou 450001, China (P.C.);Commonwealth Scientific and Industrial Research Organization Agriculture Flagship, Canberra, Australian Capital Territory 2601, Australia (Q.-H.Z.); andDepartment of Pharmaceutical Sciences, North Carolina Central University, Durham, North Carolina 27707 (J.X.)
| | - Jie Qiu
- Institute of Crop Science and Research Center for Air Pollution and Health (F.L., W.W., N.Z., C.Y., E.S., J.Q., L.F.) and Institute of Biotechnology (F.L., N.Z., X.Z.), Zhejiang University, Hangzhou 310058, China;Yunnan Academy of Tobacco Agricultural Sciences and China Tobacco Breeding Research Center at Yunnan, Yuxi 653100, China (B.X., X.W.);National Center of Tobacco Genes, Zhengzhou 450001, China (P.C.);Commonwealth Scientific and Industrial Research Organization Agriculture Flagship, Canberra, Australian Capital Territory 2601, Australia (Q.-H.Z.); andDepartment of Pharmaceutical Sciences, North Carolina Central University, Durham, North Carolina 27707 (J.X.)
| | - Qian-Hao Zhu
- Institute of Crop Science and Research Center for Air Pollution and Health (F.L., W.W., N.Z., C.Y., E.S., J.Q., L.F.) and Institute of Biotechnology (F.L., N.Z., X.Z.), Zhejiang University, Hangzhou 310058, China;Yunnan Academy of Tobacco Agricultural Sciences and China Tobacco Breeding Research Center at Yunnan, Yuxi 653100, China (B.X., X.W.);National Center of Tobacco Genes, Zhengzhou 450001, China (P.C.);Commonwealth Scientific and Industrial Research Organization Agriculture Flagship, Canberra, Australian Capital Territory 2601, Australia (Q.-H.Z.); andDepartment of Pharmaceutical Sciences, North Carolina Central University, Durham, North Carolina 27707 (J.X.)
| | - Jiahua Xie
- Institute of Crop Science and Research Center for Air Pollution and Health (F.L., W.W., N.Z., C.Y., E.S., J.Q., L.F.) and Institute of Biotechnology (F.L., N.Z., X.Z.), Zhejiang University, Hangzhou 310058, China;Yunnan Academy of Tobacco Agricultural Sciences and China Tobacco Breeding Research Center at Yunnan, Yuxi 653100, China (B.X., X.W.);National Center of Tobacco Genes, Zhengzhou 450001, China (P.C.);Commonwealth Scientific and Industrial Research Organization Agriculture Flagship, Canberra, Australian Capital Territory 2601, Australia (Q.-H.Z.); andDepartment of Pharmaceutical Sciences, North Carolina Central University, Durham, North Carolina 27707 (J.X.)
| | - Xueping Zhou
- Institute of Crop Science and Research Center for Air Pollution and Health (F.L., W.W., N.Z., C.Y., E.S., J.Q., L.F.) and Institute of Biotechnology (F.L., N.Z., X.Z.), Zhejiang University, Hangzhou 310058, China;Yunnan Academy of Tobacco Agricultural Sciences and China Tobacco Breeding Research Center at Yunnan, Yuxi 653100, China (B.X., X.W.);National Center of Tobacco Genes, Zhengzhou 450001, China (P.C.);Commonwealth Scientific and Industrial Research Organization Agriculture Flagship, Canberra, Australian Capital Territory 2601, Australia (Q.-H.Z.); andDepartment of Pharmaceutical Sciences, North Carolina Central University, Durham, North Carolina 27707 (J.X.)
| | - Longjiang Fan
- Institute of Crop Science and Research Center for Air Pollution and Health (F.L., W.W., N.Z., C.Y., E.S., J.Q., L.F.) and Institute of Biotechnology (F.L., N.Z., X.Z.), Zhejiang University, Hangzhou 310058, China;Yunnan Academy of Tobacco Agricultural Sciences and China Tobacco Breeding Research Center at Yunnan, Yuxi 653100, China (B.X., X.W.);National Center of Tobacco Genes, Zhengzhou 450001, China (P.C.);Commonwealth Scientific and Industrial Research Organization Agriculture Flagship, Canberra, Australian Capital Territory 2601, Australia (Q.-H.Z.); andDepartment of Pharmaceutical Sciences, North Carolina Central University, Durham, North Carolina 27707 (J.X.)
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Mungbean yellow mosaic Indian virus encoded AC2 protein suppresses RNA silencing by inhibiting Arabidopsis RDR6 and AGO1 activities. Virology 2015; 486:158-72. [PMID: 26433748 DOI: 10.1016/j.virol.2015.08.015] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 02/14/2015] [Accepted: 08/15/2015] [Indexed: 12/25/2022]
Abstract
RNA silencing refers to a conserved RNA-directed gene regulatory mechanism in a wide range of eukaryotes. It plays an important role in many processes including growth, development, genome stability, and antiviral defense in the plants. Geminivirus encoded AC2 is identified as an RNA silencing suppressor protein, however, the mechanism of action has not been characterized. In this paper, we elucidate another mechanism of AC2-mediated suppression activity of Mungbean Yellow Mosaic India Virus (MYMIV). The AC2 protein, unlike many other suppressors, does not bind to siRNA or dsRNA species and its suppression activity is mediated through interaction with key components of the RNA silencing pathway, viz., RDR6 and AGO1. AC2 interaction inhibits the RDR6 activity, an essential component of siRNA and tasi-RNA biogenesis and AGO1, the major slicing factor of RISC. Thus the study identifies dual sites of MYMIV-AC2 interference and probably accounts for its strong RNA silencing suppression activity.
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Li F, Xu X, Huang C, Gu Z, Cao L, Hu T, Ding M, Li Z, Zhou X. The AC5 protein encoded by Mungbean yellow mosaic India virus is a pathogenicity determinant that suppresses RNA silencing-based antiviral defenses. THE NEW PHYTOLOGIST 2015; 208:555-69. [PMID: 26010321 DOI: 10.1111/nph.13473] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2014] [Accepted: 04/16/2015] [Indexed: 06/04/2023]
Abstract
It is generally accepted that begomoviruses in the family Geminiviridae encode four proteins (from AC1/C1 to AC4/C4) using the complementary-sense DNA as template. Although AC5/C5 coding sequences are increasingly annotated in databases for many begomoviruses, the evolutionary relationships and functions of this putative protein in viral infection are obscure. Here, we demonstrate several important functions of the AC5 protein of a bipartite begomovirus, Mungbean yellow mosaic India virus (MYMIV). Mutational analyses and transgenic expression showed that AC5 plays a critical role in MYMIV infection. Ectopic expression of AC5 from a Potato virus X (PVX) vector resulted in severe mosaic symptoms followed by a hypersensitive-like response in Nicotiana benthamiana. Furthermore, MYMIV AC5 effectively suppressed post-transcriptional gene silencing induced by single-stranded but not double-stranded RNA. AC5 was also able to reverse transcriptional gene silencing of a green fluorescent protein transgene by reducing methylation of promoter sequences, probably through repressing expression of a CHH cytosine methyltransferase (DOMAINS REARRANGED METHYLTRANSFERASE2) in N. benthamiana. Our results demonstrate that MYMIV AC5 is a pathogenicity determinant and a potent RNA silencing suppressor that employs novel mechanisms to suppress antiviral defenses, and suggest that the AC5 function may be conserved among many begomoviruses.
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Affiliation(s)
- Fangfang Li
- State Key Laboratory of Rice Biology, Zhejiang University, Hangzhou, Zhejiang, 310058, China
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Xiongbiao Xu
- State Key Laboratory of Rice Biology, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Changjun Huang
- State Key Laboratory of Rice Biology, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Zhouhang Gu
- State Key Laboratory of Rice Biology, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Linge Cao
- State Key Laboratory of Rice Biology, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Tao Hu
- State Key Laboratory of Rice Biology, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Ming Ding
- Institute of Plant Protection, Yunnan Provincial Academy of Agricultural Sciences, Kunming, Yunnan, 650205, China
| | - Zhenghe Li
- State Key Laboratory of Rice Biology, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Xueping Zhou
- State Key Laboratory of Rice Biology, Zhejiang University, Hangzhou, Zhejiang, 310058, China
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
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Sharma VK, Basu S, Chakraborty S. RNAi mediated broad-spectrum transgenic resistance in Nicotiana benthamiana to chilli-infecting begomoviruses. PLANT CELL REPORTS 2015; 34:1389-99. [PMID: 25916177 DOI: 10.1007/s00299-015-1795-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Revised: 03/23/2015] [Accepted: 04/11/2015] [Indexed: 06/04/2023]
Abstract
KEY MESSAGE Two RNAi constructs were designed targeting chilli-infecting begomoviruses and associated betasatellites. Broad-spectrum resistance was achieved against multiple begomoviruses associated with leaf curl disease of chillies in India. Chilli leaf curl disease (ChiLCD) caused by begomoviruses (family: Geminiviridae) has emerged as one of the most devastating viral diseases of chilli, especially in the Indian sub-continent. The severity of disease incidence is expanding at an alarming rate due to the emergence of new begomoviruses with greater ability to infect this crop in almost all the major chilli producing regions of India. In this study, we applied the RNA interference (RNAi) based strategies to control infection of chilli-infecting begomoviruses (CIBs). For this, we have generated transgenic Nicotiana benthamiana plants harboring two different intron hairpin RNAi constructs [designated as TR1 (AC1/AC2) and TR2 (AC1/AC2/βC1)] using conserved regions of viral genome and associated betasatellite. During our study, we observed that, two lines harboring TR1 construct (13-1 and 2-4) and one line harboring TR2 construct (5-1) have shown resistance to the most predominant Indian CIBs like Chilli leaf curl virus-Pakistan isolate Varanasi, Tomato leaf curl New Delhi virus-isolate chilli, and a newly identified begomovirus species, Chilli leaf curl Vellanad virus. Resistant lines accumulated transgene-specific siRNAs, confirming RNAi-mediated resistance against these viruses. Furthermore, these resistant lines also displayed delayed symptom appearance and milder symptoms, as compared to virus-inoculated non-transgenic plants. Average viral DNA accumulation in the resistant lines was reduced up to 90% as compared to non-transgenic plants. Thus, our study demonstrated the application of RNAi-mediated approach in providing resistance against diverse monopartite and bipartite begomoviruses associated with ChiLCD.
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Affiliation(s)
- Veerandra Kumar Sharma
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India
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Hong W, Qian D, Sun R, Jiang L, Wang Y, Wei C, Zhang Z, Li Y. OsRDR6 plays role in host defense against double-stranded RNA virus, Rice Dwarf Phytoreovirus. Sci Rep 2015; 5:11324. [PMID: 26165755 PMCID: PMC4499934 DOI: 10.1038/srep11324] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Accepted: 05/13/2015] [Indexed: 11/29/2022] Open
Abstract
RNAi is a major antiviral defense response in plant and animal model systems. RNA-dependent RNA polymerase 6 (RDR6) is an essential component of RNAi, which plays an important role in the resistance against viruses in the model plants. We found previously that rice RDR6 (OsRDR6) functioned in the defense against Rice stripe virus (RSV), and Rice Dwarf Phytoreovirus (RDV) infection resulted in down-regulation of expression of RDR6. Here we report our new findings on the function of OsRDR6 against RDV. Our result showed that down-regulation of OsRDR6 through the antisense (OsRDR6AS) strategy increased rice susceptibility to RDV infection while over-expression of OsRDR6 had no effect on RDV infection. The accumulation of RDV vsiRNAs was reduced in the OsRDR6AS plants. In the OsRDR6 over-expressed plants, the levels of OsRDR6 RNA transcript and protein were much higher than that in the control plants. Interestingly, the accumulation level of OsRDR6 protein became undetectable after RDV infection. This finding indicated that the translation and/or stability of OsRDR6 protein were negatively impacted upon RDV infection. This new finding provides a new light on the function of RDR6 in plant defense response and the cross-talking between factors encoded by host plant and double-stranded RNA viruses.
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Affiliation(s)
- Wei Hong
- State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China
| | - Dan Qian
- State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China
| | - Runhong Sun
- 1] State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China [2] Institute of Plant Protection, Henan Academy of Agricultural Sciences, Henan Key Laboratory of Crop Pest Control, Zhengzhou 450002, China
| | - Lin Jiang
- State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China
| | - Yu Wang
- State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China
| | - Chunhong Wei
- State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China
| | - Zhongkai Zhang
- Ministry of Agriculture Key Lab of Southwestern Crop Gene Resources and Germplasm Innovation, Yunnan Provincial Key Lab of Agricultural Biotechnology, Biotechnology and Germplasm Resources Institute, Yunnan Academy of Agricultural Sciences, Kunming 650223, China
| | - Yi Li
- State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China
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Patil BL, Fauquet CM. Studies on differential behavior of cassava mosaic geminivirus DNA components, symptom recovery patterns, and their siRNA profiles. Virus Genes 2015; 50:474-86. [PMID: 25724177 DOI: 10.1007/s11262-015-1184-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 02/18/2015] [Indexed: 11/28/2022]
Abstract
Cassava mosaic disease caused by cassava mosaic geminiviruses (CMGs) with bipartite genome organization is a major constraint for production of cassava in the African continent and the Indian sub-continent. Currently, there are eleven recognized species of CMGs, and several diverse isolates represent them, with vast amount of sequence variability, reflecting into diversity of symptom severity/phenotypes. Here, we make a systematic effort to study the infection dynamics of several species of CMGs and their isolates. Further, we try to identify the genomic component of CMGs contributing to the manifestation of diverse patterns of symptoms and the molecular basis for the differential behavior of CMGs. The pseudo-recombination studies carried out by swapping of DNA-A and DNA-B components of the CMGs revealed that the DNA-B component significantly contributes to the symptom severity. Past studies had shown that the DNA-A component of Sri Lankan cassava mosaic virus shows monopartite feature. Thus, the ability of DNA-A component alone, to replicate and move systemically in the host plant with inherent monopartite features was investigated for all the CMGs. Geminiviruses are known to trigger gene silencing and are also its target, resulting in recovery of the host plant from viral infection. In the collection of several different CMG species and isolates we had, there was a vast variability in their recovery and non-recovery phenotypes. To understand the molecular basis of this, the origin and distribution of virus-derived small interfering RNAs were mapped across their genome and across the CMG-infected symptomatic Nicotiana benthamiana.
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Csorba T, Kontra L, Burgyán J. viral silencing suppressors: Tools forged to fine-tune host-pathogen coexistence. Virology 2015; 479-480:85-103. [DOI: 10.1016/j.virol.2015.02.028] [Citation(s) in RCA: 368] [Impact Index Per Article: 40.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Revised: 01/31/2015] [Accepted: 02/16/2015] [Indexed: 12/27/2022]
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136
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Viral factors involved in plant pathogenesis. Curr Opin Virol 2015; 11:21-30. [DOI: 10.1016/j.coviro.2015.01.001] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 01/06/2015] [Indexed: 12/31/2022]
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Ammara UE, Mansoor S, Saeed M, Amin I, Briddon RW, Al-Sadi AM. RNA interference-based resistance in transgenic tomato plants against Tomato yellow leaf curl virus-Oman (TYLCV-OM) and its associated betasatellite. Virol J 2015; 12:38. [PMID: 25890080 PMCID: PMC4359554 DOI: 10.1186/s12985-015-0263-y] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Accepted: 02/10/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Tomato yellow leaf curl virus (TYLCV), a monopartite begomovirus (family Geminiviridae) is responsible for heavy yield losses for tomato production around the globe. In Oman at least five distinct begomoviruses cause disease in tomato, including TYLCV. Unusually, TYLCV infections in Oman are sometimes associated with a betasatellite (Tomato leaf curl betasatellite [ToLCB]; a symptom modulating satellite). RNA interference (RNAi) can be used to develop resistance against begomoviruses at either the transcriptional or post-transcriptional levels. RESULTS A hairpin RNAi (hpRNAi) construct to express double-stranded RNA homologous to sequences of the intergenic region, coat protein gene, V2 gene and replication-associated gene of Tomato yellow leaf curl virus-Oman (TYLCV-OM) was produced. Initially, transient expression of the hpRNAi construct at the site of virus inoculation was shown to reduce the number of plants developing symptoms when inoculated with either TYLCV-OM or TYLCV-OM with ToLCB-OM to Nicotiana benthamiana or tomato. Solanum lycopersicum L. cv. Pusa Ruby was transformed with the hpRNAi construct and nine confirmed transgenic lines were obtained and challenged with TYLCV-OM and ToLCB-OM by Agrobacterium-mediated inoculation. For all but one line, for which all plants remained symptomless, inoculation with TYLCV-OM led to a proportion (≤25%) of tomato plants developing symptoms of infection. For inoculation with TYLCV-OM and ToLCB-OM all lines showed a proportion of plants (≤45%) symptomatic. However, for all infected transgenic plants the symptoms were milder and virus titre in plants was lower than in infected non-transgenic tomato plants. CONCLUSIONS These results show that RNAi can be used to develop resistance against geminiviruses in tomato. The resistance in this case is not immunity but does reduce the severity of infections and virus titer. Also, the betasatellite may compromise resistance, increasing the proportion of plants which ultimately show symptoms.
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Affiliation(s)
- Um e Ammara
- Department of Crop Sciences, College of Agriculture and Marine Sciences, Sultan Qaboos University, P.O. Box-34, 123, Al-Khod, Oman.
| | - Shahid Mansoor
- Agricultural Biotechnology Division, National Institute for Biotechnology and Genetic Engineering (NIBGE), P O Box 577, Jhang Road, Faisalabad, Pakistan.
| | - Muhammad Saeed
- Agricultural Biotechnology Division, National Institute for Biotechnology and Genetic Engineering (NIBGE), P O Box 577, Jhang Road, Faisalabad, Pakistan.
| | - Imran Amin
- Agricultural Biotechnology Division, National Institute for Biotechnology and Genetic Engineering (NIBGE), P O Box 577, Jhang Road, Faisalabad, Pakistan.
| | - Rob W Briddon
- Agricultural Biotechnology Division, National Institute for Biotechnology and Genetic Engineering (NIBGE), P O Box 577, Jhang Road, Faisalabad, Pakistan.
| | - Abdullah Mohammed Al-Sadi
- Department of Crop Sciences, College of Agriculture and Marine Sciences, Sultan Qaboos University, P.O. Box-34, 123, Al-Khod, Oman.
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Nicaise V. Crop immunity against viruses: outcomes and future challenges. FRONTIERS IN PLANT SCIENCE 2014; 5:660. [PMID: 25484888 PMCID: PMC4240047 DOI: 10.3389/fpls.2014.00660] [Citation(s) in RCA: 176] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Accepted: 11/04/2014] [Indexed: 05/02/2023]
Abstract
Viruses cause epidemics on all major cultures of agronomic importance, representing a serious threat to global food security. As strict intracellular pathogens, they cannot be controlled chemically and prophylactic measures consist mainly in the destruction of infected plants and excessive pesticide applications to limit the population of vector organisms. A powerful alternative frequently employed in agriculture relies on the use of crop genetic resistances, approach that depends on mechanisms governing plant-virus interactions. Hence, knowledge related to the molecular bases of viral infections and crop resistances is key to face viral attacks in fields. Over the past 80 years, great advances have been made on our understanding of plant immunity against viruses. Although most of the known natural resistance genes have long been dominant R genes (encoding NBS-LRR proteins), a vast number of crop recessive resistance genes were cloned in the last decade, emphasizing another evolutive strategy to block viruses. In addition, the discovery of RNA interference pathways highlighted a very efficient antiviral system targeting the infectious agent at the nucleic acid level. Insidiously, plant viruses evolve and often acquire the ability to overcome the resistances employed by breeders. The development of efficient and durable resistances able to withstand the extreme genetic plasticity of viruses therefore represents a major challenge for the coming years. This review aims at describing some of the most devastating diseases caused by viruses on crops and summarizes current knowledge about plant-virus interactions, focusing on resistance mechanisms that prevent or limit viral infection in plants. In addition, I will discuss the current outcomes of the actions employed to control viral diseases in fields and the future investigations that need to be undertaken to develop sustainable broad-spectrum crop resistances against viruses.
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Affiliation(s)
- Valérie Nicaise
- Fruit Biology and Pathology, Virology Laboratory, Institut National de la Recherche Agronomique, University of BordeauxUMR 1332, Villenave d’Ornon, France
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