Agroinfiltration of Cauliflower mosaic virus Gene VI Elicits Hypersensitive Response in Nicotiana Species

Cauliflower mosaic virus strain W260 induces hypersensitive response (HR) in Nicotiana edwardsonii and systemic cell death in N. clevelandii. In contrast, the D4 strain of Cauliflower mosaic virus evades the host defenses in Nicotiana species; it induces chlorotic primary lesions and a systemic mosaic in both hosts. Previous studies with chimeric viruses had indicated that gene VI of W260 was responsible for elicitation of HR or cell death. To prove conclusively that W260 gene VI is responsible, we inserted gene VI of W260 and D4 into the Agrobacterium tumefaciens binary vector pKYLX7. Agroinfiltration of these constructs into the leaves of N. edwardsonii and N. clevelandii revealed that gene VI of W260 elicited HR in N. edwardsonii 4 to 5 days after infiltration and cell death in N. clevelandii approximately 9 to 12 days after infiltration. In contrast, gene VI of D4 did not elicit HR or cell death in either Nicotiana species. A frameshift mutation introduced into gene VI of W260 abolished its ability to elicit HR or cell death in both Nicotiana species, demonstrating that the elicitor is the gene VI protein.

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Uncoupling Resistance from Cell Death in the Hypersensitive Response of Nicotiana Species to Cauliflower mosaic virus Infection

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi.2001.14.1.31 ◽

2001 ◽

Vol 14 (1) ◽

pp. 31-41 ◽

Cited By ~ 54

Author(s):

Anthony B. Cole ◽

Lóránt Király ◽

Kathleen Ross ◽

James E. Schoelz

Keyword(s):

Cell Death ◽

Virus Infection ◽

Mosaic Virus ◽

Hypersensitive Response ◽

Cauliflower Mosaic Virus ◽

Resistance Response ◽

Pr Protein ◽

Pathogenesis Related ◽

Lines Of Evidence ◽

Mosaic Virus Infection

Cauliflower mosaic virus strain W260 elicits a hypersensitive response (HR) in leaves of Nicotiana edwardsonii, an interspecific hybrid derived from a cross between N. glutinosa and N. clevelandii. Interestingly, we found that N. glutinosa is resistant to W260, but responds with local chlorotic lesions rather than necrotic lesions. In contrast, N. clevelandii responds to W260 with systemic cell death. The reactions of the progenitors of N. edwardsonii to W260 infection indicated that each contributed a factor toward the development of HR. In this study, we present two lines of evidence to show that the resistance and cell death that comprise the HR elicited by W260 can indeed be uncoupled. First, we showed that the non-necrotic resistance response of N. glutinosa could be converted to HR when these plants were crossed with N. clevelandii. Second, we found that cell death and resistance segregated independently in the F2 population of a cross between N. edwardsonii and N. clevelandii. We concluded that the resistance of N. edwardsonii to W260 infection was conditioned by a gene derived from N. glutinosa, whereas cell death was conditioned by a gene derived from N. clevelandii. An analysis of pathogenesis-related (PR) protein expression in response to W260 infection revealed that elicitation of PR proteins was associated with resistance rather than with the onset of cell death.

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The Plant Gene CCD1 Selectively Blocks Cell Death During the Hypersensitive Response to Cauliflower Mosaic Virus Infection

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-18-0212 ◽

2005 ◽

Vol 18 (3) ◽

pp. 212-219 ◽

Cited By ~ 23

Author(s):

John Cawly ◽

Anthony B. Cole ◽

Lóránt Király ◽

Wenping Qiu ◽

James E. Schoelz

Keyword(s):

Cell Death ◽

Mosaic Virus ◽

Hypersensitive Response ◽

Plant Pathogens ◽

Plant Viruses ◽

Cauliflower Mosaic Virus ◽

Plant Gene ◽

Cell Death Pathway ◽

Resistance Pathway ◽

Key Characteristics

The P6 protein of Cauliflower mosaic virus (CaMV) W260 elicits a hypersensitive response (HR) on inoculated leaves of Nicotiana edwardsonii. This defense response, common to many plant pathogens, has two key characteristics, cell death within the initially infected tissues and restriction of the pathogen to this area. We present evidence that a plant gene designated CCD1, originally identified in N. bigelovii, can selectively block the cell death pathway during HR, whereas the resistance pathway against W260 remains intact. Suppression of cell death was evident not only macroscopically but also microscopically. The suppression of HR-mediated cell death was specific to CaMV, as Tobacco mosaic virus was able to elicit HR in the plants that contained CCD1. CCD1 also blocks the development of a systemic cell death symptom induced specifically by the P6 protein of W260 in N. clevelandii. Introgression of CCD1 from N. bigelovii into N. clevelandii blocked the development of systemic cell death in response to W260 infection but could not prevent systemic cell death induced by Tomato bushy stunt virus. Thus, CCD1 blocks both local and systemic cell death induced by P6 of W260 but does not act as a general suppressor of cell death induced by other plant viruses. Furthermore, experiments with CCD1 provide further evidence that cell death could be uncoupled from resistance in the HR of Nicotiana edwardsonii to CaMV W260.

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Systemic Cell Death Is Elicited by the Interaction of a Single Gene in Nicotiana clevelandii and Gene VI of Cauliflower Mosaic Virus

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi.1999.12.10.919 ◽

1999 ◽

Vol 12 (10) ◽

pp. 919-925 ◽

Cited By ~ 50

Author(s):

Lóránt Király ◽

Anthony B. Cole ◽

June E. Bourque ◽

James E. Schoelz

Keyword(s):

Cell Death ◽

Mosaic Virus ◽

Hypersensitive Response ◽

Single Gene ◽

Cauliflower Mosaic Virus ◽

Host Gene ◽

Mosaic Symptom ◽

Single Host ◽

Cell Death Gene ◽

Nicotiana Clevelandii

Cauliflower mosaic virus (CaMV) strains D4 and W260 can be distinguished by the type of symptoms they induce in Nicotiana clevelandii and N. edwardsonii. W260 induces systemic cell death in addition to a mosaic symptom in N. clevelandii and a hypersensitive response (HR) in N. edwardsonii, whereas D4 induces a systemic mosaic in both hosts. To determine which W260 genes are responsible for systemic cell death, chimeric viruses were constructed between the D4 and W260 strains. It was found that W260 gene VI was responsible for the elicitation of systemic cell death; previous studies had shown that this same gene elicited HR in N. edwardsonii. An immunological analysis of plants infected with W260 or D4 indicated that the systemic cell death symptom was not associated with enhanced levels of either W260 virions or the W260 gene VI product. To investigate the inheritance of systemic cell death, crosses were made between N. clevelandii and N. bigelovii, a host that reacts with a systemic mosaic symptom upon infection with W260. All F1 plants developed a systemic mosaic after inoculation with W260, whereas the F2 generation segregated 3:1 for systemic mosaic versus cell death. The plant gene responsible for cell death was designated ccd1, for CaMV cell death gene. These results demonstrate that the systemic cell death symptom in N. clevelandii is induced by the interaction between a single host gene and gene VI of CaMV.

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Physical map of DNA from a new cauliflower mosaic virus strain

Gene ◽

10.1016/0378-1119(78)90019-7 ◽

1978 ◽

Vol 4 (3) ◽

pp. 213-226 ◽

Cited By ~ 20

Author(s):

Geneviève Lebeurier ◽

Odile Whitechurch ◽

Agnès Lesot ◽

Léon Hirth

Keyword(s):

Mosaic Virus ◽

Virus Strain ◽

Physical Map ◽

Cauliflower Mosaic Virus

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Pathogen-induced programmed cell death in tobacco

Journal of Cell Science ◽

10.1242/jcs.110.11.1333 ◽

1997 ◽

Vol 110 (11) ◽

pp. 1333-1344 ◽

Cited By ~ 1

Author(s):

R. Mittler ◽

L. Simon ◽

E. Lam

Keyword(s):

Cell Death ◽

Programmed Cell Death ◽

Tobacco Mosaic Virus ◽

Chloroplast Dna ◽

Mosaic Virus ◽

Hypersensitive Response ◽

Nuclear Periphery ◽

Death Process ◽

Tobacco Plants ◽

Systemic Spread

Sacrificing an infected cell or cells in order to prevent systemic spread of a pathogen appears to be a conserved strategy in both plants and animals. We studied some of the morphological and biochemical events that accompany programmed cell death during the hypersensitive response of tobacco plants infected with tobacco mosaic virus. Certain aspects of this cell death process appeared to be similar to those that take place during apoptosis in animal cells. These included condensation and vacuolization of the cytoplasm and cleavage of nuclear DNA to 50 kb fragments. In contrast, internucleosomal fragmentation, condensation of chromatin at the nuclear periphery and apoptotic bodies were not observed in tobacco plants during tobacco mosaic virus-induced hypersensitive response. A unique aspect of programmed cell death during the hypersensitive response of tobacco to tobacco mosaic virus involved an increase in the amount of monomeric chloroplast DNA. Morphological changes to the chloroplast and cytosol of tobacco cells and increase in monomeric chloroplast DNA occurred prior to gross changes in nuclear morphology and significant chromatin cleavage. Our findings suggest that certain aspects of programmed cell death may have been conserved during the evolution of plants and animals.

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Identification of the domains of cauliflower mosaic virus protein P6 responsible for suppression of RNA silencing and salicylic acid signalling

Journal of General Virology ◽

10.1099/vir.0.057729-0 ◽

2013 ◽

Vol 94 (12) ◽

pp. 2777-2789 ◽

Cited By ~ 31

Author(s):

Janet Laird ◽

Carol McInally ◽

Craig Carr ◽

Sowjanya Doddiah ◽

Gary Yates ◽

...

Keyword(s):

Cell Death ◽

Salicylic Acid ◽

Mosaic Virus ◽

Virus Replication ◽

Nuclear Export ◽

Rna Silencing ◽

Nuclear Export Signal ◽

Genetically Modified Crops ◽

Cauliflower Mosaic Virus ◽

Virus Protein

Cauliflower mosaic virus (CaMV) encodes a 520 aa polypeptide, P6, which participates in several essential activities in the virus life cycle including suppressing RNA silencing and salicylic acid-responsive defence signalling. We infected Arabidopsis with CaMV mutants containing short in-frame deletions within the P6 ORF. A deletion in the distal end of domain D-I (the N-terminal 112 aa) of P6 did not affect virus replication but compromised symptom development and curtailed the ability to restore GFP fluorescence in a GFP-silenced transgenic Arabidopsis line. A deletion in the minimum transactivator domain was defective in virus replication but retained the capacity to suppress RNA silencing locally. Symptom expression in CaMV-infected plants is apparently linked to the ability to suppress RNA silencing. When transiently co-expressed with tomato bushy stunt virus P19, an elicitor of programmed cell death in Nicotiana tabacum, WT P6 suppressed the hypersensitive response, but three mutants, two with deletions within the distal end of domain D-I and one involving the N-terminal nuclear export signal (NES), were unable to do so. Deleting the N-terminal 20 aa also abolished the suppression of pathogen-associated molecular pattern-dependent PR1a expression following agroinfiltration. However, the two other deletions in domain D-I retained this activity, evidence that the mechanisms underlying these functions are not identical. The D-I domain of P6 when expressed alone failed to suppress either cell death or PR1a expression and is therefore necessary but not sufficient for all three defence suppression activities. Consequently, concerns about the biosafety of genetically modified crops carrying truncated ORFVI sequences appear unfounded.

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Genome-Wide Identification Reveals That Nicotiana benthamiana Hypersensitive Response (HR)-Like Lesion Inducing Protein 4 (NbHRLI4) Mediates Cell Death and Salicylic Acid-Dependent Defense Responses to Turnip Mosaic Virus

Frontiers in Plant Science ◽

10.3389/fpls.2021.627315 ◽

2021 ◽

Vol 12 ◽

Author(s):

Xinyang Wu ◽

Yuchao Lai ◽

Shaofei Rao ◽

Lanqing Lv ◽

Mengfei Ji ◽

...

Keyword(s):

Cell Death ◽

Salicylic Acid ◽

Mosaic Virus ◽

Hypersensitive Response ◽

Nicotiana Benthamiana ◽

Defense Responses ◽

Turnip Mosaic Virus ◽

Genome Wide ◽

Transient Overexpression ◽

Basal Immunity

Hypersensitive response (HR)-like cell death is an important mechanism that mediates the plant response to pathogens. In our previous study, we reported that NbHIR3s regulate HR-like cell death and basal immunity. However, the host genes involved in HR have rarely been studied. Here, we used transcriptome sequencing to identify Niben101Scf02063g02012.1, an HR-like lesion inducing protein (HRLI) in Nicotiana benthamiana that was significantly reduced by turnip mosaic virus (TuMV). HRLIs are uncharacterized proteins which may regulate the HR process. We identified all six HRLIs in N. benthamiana and functionally analyzed Niben101Scf02063g02012.1, named NbHRLI4, in response to TuMV. Silencing of NbHRLI4 increased TuMV accumulation, while overexpression of NbHRLI4 conferred resistance to TuMV. Transient overexpression of NbHRLI4 caused cell death with an increase in the expression of salicylic acid (SA) pathway genes but led to less cell death level and weaker immunity in plants expressing NahG. Thus, we have characterized NbHRLI4 as an inducer of cell death and an antiviral regulator of TuMV infection in a SA-mediated manner.

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