Progress 10/01/02 to 09/30/05
Outputs
The aim of this project is to develop multiple tomato virus resistance using transgenic or molecular methodologies. An Agrobacterium transgenic tomato regeneration system is being optimized for 9 tomato heirloom varieties (Roma, Gardener's Delight, Super Beefsteak, Red Brandywine, Rutgers, Red Mortgage Lifter, Prince Borghese, Long Keeper, Super Italian Paste) with TSWV (Tomato Spotted Wilt Virus) construct N5/PGA-4 (which possesses complete N gene of TSWV). Our initial kanamycin antibiotic selection rate standard for tomato, 50 mg/l, was too toxic for selecting transgenic tomato lines of all 9 varieties tested. We are now evaluating the use of lower kanamycin levels for selection and the use of incremental or stepwise increase in kanamycin levels for selection. Since virus surveys indicated that TSWV was the major virus occurring on tomatoes on Oahu and Maui, we are now focusing this project at broadening TSWV resistance (rather than including transgenic resistance to
a second virus such as PVY or TMV). We believe this will best provide for stable virus resistance in tomato in Hawaii. Previously, Cho developed and released several commercial tomato varieties with good field resistance derived from several wild relatives of tomato in Hawaii. These were successful for a number of years until different strains of TSWV capable of overcoming the resistance became prevalent. However, Gubba & Gonsalves further demonstrated the value of combining natural resistance and transgenic resistance to broaden tospovirus resistance in tomato to include TSWV and Groundnut Ringspot Virus (GRSV), a different but related tospovirus of tomato, which is not yet present in Hawaii. Hence, we will use the Sw-5 gene originally obtained from Lycopersicon peruvianum, and present in Geneva 80, by crossing the transgenic plants with Geneva 80. In addition, Cho's original lines will also be transformed for TSWV resistance and also crossed with Geneva 80 to introduce the Sw-5
gene. These lines also will be evaluated for broad TSWV resistance.
Impacts
This project should result in the development and release of tomato varieties with broad and stable resistance to all or nearly all strains of Tomato Spotted Wilt Virus and its related virus, Groundnut Spotted Wilt Virus. Thus, Hawaii's tomato growers will have a long term solution to the major tomato virus affecting tomato production and economic viability in Hawaii.
Publications
- No publications reported this period
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Progress 10/01/03 to 09/30/04
Outputs
This project was initiated in October, 2002. Last year we reported that the hurdle of regulatory approvals for the necessary virus strains, plasmids, and constructs from Dr. Gonsalves laboratory was taking longer than we had anticipated. This was necessary as Dr. Gonsalves left Cornell University to become the center director of PBARC, in Hilo. Indeed, it has taken an additional year to receive the necessary approvals from USDA/APHIS and the Hawaii DOA. We are scheduled to receive shipment of the materials (TSWV, PVY, and TEV virus strains and bacterial cultures (Agrobacterium tumefaciens and E. coli) containing plasmids/vectors and constructs from Dr. Gonsalves' previous laboratory at the NYS Agricultural Experiment Station, Cornell University in Geneva, NY) during the last week of March, 2004. Consequently, we have made no progress (and have not expended much of the funding) toward transforming tomato lines for multiple virus resistance. In the past year, we
initiated a survey of viruses occurring on tomatoes on the island of Oahu. We have obtained over 40 samples from 4 different farms on Oahu. The major virus occurring on tomato on Oahu is Tomato Spotted Wilt Virus (TSWV), followed by Potato Virus Y (PVY), which was found on 84% and 16% of the samples respectively. Tobacco Mosaic Virus (TMV) and Tobacco Etch Virus (TEV) were not observed. As reported last year, an effort is being made to break an important hybrid variety (grown by Hawaii's largest tomato grower) by our collaborator, Dr. J. Cho. He is now evaluating several 4th generation inbred lines for horticultural traits characteristic of the parental hybrid line from which they were derived. These inbreds will be some of the initial tomato lines to be transformed this next year. We expect to be able to use these lines directly as inbreds or to intercross them to produce hybrids. They will need to be compared to the parental line for horticultural performance, after being
transformed for multiple virus resistance. In addition, we are targeting some heirloom varieties that are making a come back for the vine-ripened market. We will also transform a UH inbred line, Healani, and 2 research lines, Geneva 80 and Vender, so that these lines can be used by breeders in order to utilize the resistance we develop.
Impacts
Building on the success of developing transgenic resistance in papaya to Papaya ringspot virus, we hope to develop resistance in tomato to 2 of the most important tomato viruses limiting tomato production in Hawaii, TSWV and PVY. Scientists from UH and ARS will target both viruses in a single transformation event, utilizing only a segment of the coat protein gene of each virus engineered into a single construct used to transform tomatoes. This segmented gene approach has been successfully demonstrated in a model tobacco system.
Publications
- No publications reported this period
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Progress 10/01/02 to 09/30/03
Outputs
No progress to report.
Impacts
No impact to report.
Publications
- No publications reported this period
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