Date August 26, 1992

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 1/92 to 12/92

Anticipated Date of Project Completion/Final Report 12/92

Individual(s) Conducting Project:

(List Project Leader First)

James Moyer - Title Professor

TelephoneNumber (919) 515-7984

Margaret Daub - (919)515-6986 Title Associate Professor

Ronald Jones - Title Professor

Control of Tomato Spotted Wilt Virus in Floral Crops

James Moyer, Margaret Daub, and Ronald Jones

North Carolina State University

Progress Report to the American Floral Endowment, 8/26/92

A. Project Objectives:

The original proposal contained four objectives:

1) to collect

TSWV-Iike isolates from different floral crop hosts and geographic regions,

2) to

develop biological and biochemical assays for these virus-host combinations,

3) to

compare the properties of floral crop isolates with each other and with standard

isolates of TSWV, and

4) to develop resistance to TSWV-like viruses in floral crops.

B. Overall Summary:

Objectives 1-3 were completed prior to our March 1992 report,

and details of our accomplishments were outlined in that report. Briefly, isolation and

characterization of TSWV isolates from floral crops led to the identification of a new

virus, impatiens necrotic spot virus (formerly TSWV-1). Antisera were developed and

are used world-wide for accurate identification of INSV-infected material. Biological

and serological diagnostic assays have been developed for use by others. Host range

studies have been completed, the results of which are being used to develop a series of

monoclonal antibodies useful for strain diagnosis and identification. Our current

efforts are directed toward objective 4, the development of resistance in major floral

crops by genetically-engineered cross protection, i.e. the transfer of genes from the

virus into plants which protects them against virus infection.

C. Results to Date:

Our work to date on objective 4 has focused on the development of

techniques to transfer virus genes into chrysanthemum. Protocols were developed for

regenerating whole plants from cultured cells for three cultivars of chrysanthemum,

Iridon, Hekla, and Polaris. The gene coding for the nucleocapsid gene from TSWV

was isolated and successfully transferred into Iridon cells, and whole plants containing

the gene have been recovered. These plants are not adversely affected by the presence

of the gene and appear normal in phenotype. Current efforts are directed at

determining the levels of TSWV resistance expressed by these plants.

D. Future Plans Covered by the Endowment Grant:

Our goal for the remaining period covered by the Endowment grant is

to accurately determine the levels of resistance expressed by our transformed plants.

In addition, we are working to develop methods for virus gene transfer into Polaris.

E. Anticipated Benefits for Floral Industry:

Characterization of INSV as a distinct TSWV-like

virus and development of antisera has led to useful diagnostic tools for this virus in

floral crops. The antisera is available in kit format through Agdia, Inc. It is hoped

that current efforts on developing monoclonal antibodies will lead to development of

kits for diagnosis of all TSWV-like viruses. Our work on chrysanthemums engineered

with genes from TSWV, if successful, will be the first example of an ornamental crop

genetically engineered to resist virus infection. Further, the protocols developed for

gene transfer and whole plant regeneration will be applicable for the introduction of

other genes affecting traits such as color, senescence, and tolerance to other pathogens

and insects.

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