Date September 4, 1991

Title of Project Control of Tomato Spotted Wilt Virus in Floral Crops

Institution where work is being conducted North Carolina State University

Amount of Endowment Grant $ 35, 000
Covering Period Jan. ‘91 to Dec. ‘91

Anticipated Date of Project Completion/Final Report December 1992

Individual(s) Conducting Project:

(List Project Leader First)

James Moyer - Title Professor

Telephone Number 919-515-2735

Fax 919-515-7716

Margaret Daub - Title Associate Professor

Ronald Jones - Title Professor

Control of Tomato Spotted Wilt Virus in Floral Crops

J. W. Moyer, M. E. Daub, and R. K. Jones

North Carolina State University

Progress Report to the American Floral Endowment, 9/4/91

A. Project Objectives:

The original proposal contained four objectives:

1) To

collect TSWV-like isolates from different floral crop hosts and geographic

regions.

2) Develop biological and biochemical assays for these virus-host

combinations.

3) Compare the biological and biochemical properties of floral

crop-specific isolates with each other and with standard isolates of TSWV.

4)

To develop resistance to these viruses in floral Crops.

B. Overall Summary:

Our early research focused on the identification and

characterization of the TSWV-like viruses found in floral crops. We identified

a new virus which has been named Impatiens necrotic spot virus (formerly

TSWV-I). This was the first report of serological diversity in the TSWV group

of viruses and was recently cited in a review of the highlights of virology

(plant and animal) for 1990. Antiserum was made for diagnostic and research

purposes. We have also collected approximately twenty TSWV-like isolates from

floral crops from all over the United States. These played an important role in

improving our diagnostic tools, in providing an accurate representation of the

TSWV-Iike isolates in the floral crop industry and will be invaluable in testing

resistant cultivars. We have tested diagnostic approaches, both biological and

serological, developed in our lab and those developed and recommended by others

for use in routine diagnosis and for clean stock programs. Much of this

information has been put to use not only by ourselves, but also by

diagnosticians in public and private plant disease clinics. We have also

conducted a thorough comparison of the different isolates. Host range studies

have been completed and a student (not supported by this grant) is currently

conducting a detailed serological analysis with polyclonal and monoclonal

antibodies. A significant finding of his research is that a mcnoclonal antibody

which reacts with both L and I types has been identified which will hopefully

lead to a single test for all TSWV-like isolates. we have also completed the

biochemical characterization of the TSWV isolate and isolated viral genes from

both serotypes which can be used to impart resistance to these viruses. Thus,

we have essentially completed Objectives 1 - 3. Manuscript status is attached.

C. Recent Results and Future Activity:

During the past few months the emphasis in

our research has moved from biochemical characterization and isolation of

specific viral genes to the development of resistant plants. Since it would be

impractical to attempt to identify a source of resistance for each of the floral

crops, we have chosen to take advantage of the newly emerging technique of

genetically engineered cross-protection which is explained in our proposal. As

we have the necessary genes isolated we are currently developing the

regeneration and transformation Protocols for the introduction of the genes into

the specific floral crops. We are currently working on chrysanthemum and intend

to extend this research to other sensitive floral crops. Chrysanthemum was

chosen because of the availability of sensitive cultivars, tissue culture

information and sensitivity to the bacterium used to carry the transformation

vector. In short, we chose chrysanthemum because it was the crop which had the

highest probability of our being able to develop resistant plants by these

procedures. We have identified several critical factors which have allowed us

to extend the range of cultivars capable of being regenerated by existing

techniques. Regeneration of plants from leaf pieces is necessary for the

transformation step. We have now begun investigations of factors which will

allow us to introduce the virus genes into the plants genes (transformation)

thus imparting the resistance to the viruses.

C. Anticipated Benefits for Floral Industry:

Our research on the nature of these viruses

has provided the basis for diagnosis. The antisera, in a kit format, is

commercially available through Agdia, Inc. Research underway way is anticipated

to lead to one kit for all TSWV-like viruses. Our current research is directed

at developing procedures for the introduction of virus resistance genes into

important floral crops. These techniques will also be applicable for the

introduction of other genes such as resistance to other viruses, herbicide

tolerance, insect resistance and control of ethylene production.

D. Status of research publications supported all or in part by the American Floral Endowment:

Law, M. D., and J. W. Moyer. 1989. Physicochemical analysis of a serologically

distinct tomato spotted wilt virus strain. Phytopathology 79: 1157 (abstract).

*Law, M. D. and J. W. Moyer. 1990. A tomato spotted wilt-like virus with a

serologically distinct N protein. J. General Virology 71:933-938. (cited in

highlights in virology for 1990 covers both plant and animal viruses).

**Urban, L., Huang, P., and J. W. Moyer. 1991 Cytoplasmic inclusions in

cells infected with isolates of the L- and I- serogroups of tomato spotted wilt

virus. Phytopathology 81:

***Law, M. D., Speck, J., and J. W. Moyer. 1991. Nucleotide sequence of the 3′

non-coding region and N gene of the S RN11, of a serologically distinct

tospovirus. J. of Gen. Virol. In Press.

* Original description of TSWV-I type virus.

** Part of the comparison of TSWV-Iike viruses. This aspect has been given to a

student on state support and will be published soon. AFE support will be

acknowledged.

*** This paper describes the gene to be used for resistance to the I type virus.

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