Brief Summary of Minutes of Annual Meeting

The meeting was called to order by John Hu. Information on the meeting and field trip itineraries were presented and discussed.

Catherine Chan-Haldebrendt (U. of HI) provided an overview of Hawaiian agriculture. Farm revenues were estimated at about $570,000,000 with pineapple, sugarcane, and seed being the top three industries. She urged us to come back to Hawaii and spend money to help offset the recent drop in tourism!

Ralph Cavalieri, the WCC-20 Advisor, addressed the gathering via phone link from Pullman, WA. He informed us that the Committee has been renewed for 5 more years. He mentioned that moneys may become available for ?agri-security? programs, and that this is something the members should consider.

The site for next years meeting was discussed and debated. No firm plans were decided upon. Suggested sites included and University of Guelph, Colorado, and UC Davis. (After the meeting, John Hu discussed with Dr. Baozhong Meng, plant virologist at University of Guelph. Dr. Meng was interested in hosting the 2003 annual meeting.)

The minutes of last years meeting in Kearneysville, WV were distributed by Gary Kinard and accepted by the members. Jim Crosslin was selected as secretary of this year?s meeting.

Roberto Michelutti had photos from the last year?s meeting.

Field Trip, May 17, 2002, Oahu

The sites we visited included the Waimanalo Experiment Station where we observed banana bunch top virus (BBTV) symptoms. PRSV was also observed on nontransgenic papaya as compared to the excellent control of PRSV observed in transgenic ?Rainbow?. We also visited the Hawaiian Ag. Research Center, Kunia, where we say sugarcane, kava, papaya, coffee, and taro. We also visited a watercress operation not far from Pearl Harbor, where a phytoplasma disease is a problem. The next stop was a Dole pineapple production field near the north shore of Oahu where we saw the symptoms of pineapple mealybug wilt. All of us were impressed with the time and effort which is required to produce a pineapple crop.

Field Trip, May 20, 2002, Hawaii

We first visited the Pacific Basin Tropical Plant Genetic Resource Unit of USDA near Hilo. The research leader, Dr. Zee, showed us some of the collection of palm, guava, mountain apple, coffee, tea, papaya, breadfruit, ginger, and other crops. There was some ?beautiful? citrus tristeza virus too. Next stop was Mauna Kea banana plantation (no cameras allowed!!) where we saw a commercial banana operation. For a lunch stop, we went to over 6,000 feet on Mauna Kea and saw symptoms of a phytoplasma disease of the native Dodonea viscosa. A trip to Orchid Isle Dendrobiums followed where we saw a commercial orchid operation and the spotting caused by Cymbidium mosaic virus. Last stop was Volcani Isle Fruit Company, Kapoho (visit them at papayas.net) to see papaya and apple banana production fields.


Information compiled by Jim Crosslin and modified by John Hu

Steve Ferreira, U. of HI. Steve provided history of the work which produced transgenic papaya with resistance to papaya ringspot virus (PRSV). This work has allowed the continued production of papaya in areas where the virus made papaya production nearly impossible. The major cultivar now grown is ?Rainbow? and it has been well received by growers and consumers alike. He also mentioned ongoing work to identify delayed ripening genes for use in papaya and the use of consensus ?synthetic? genes in order to broaden the anti-PRSV activity.

Maureen Fitch, Pacific Basin Ag. Res. Center, HI. Maureen discussed the breeding and clonal propagation of PRSV resistant papayas other than ?Rainbow? to meet the needs of other growing areas and markets. They are working on tissue culture procedures for clonal propagation of the desirable types.

Susan Schenk, Hawaii Ag. Res. Center, HI. Sugarcane is widely infected around the world by Sugarcane Yellow Leaf Virus, a Polerovirus of the Luteoviridae family that produces leaf yellowing and plant growth reduction. It is transmitted by the sugarcane aphid, Melanaphis sacchari. A tissue blot immunoassay diagnostic technique allowed plantation surveys and determination of the extent of virus infection and the sugarcane cultivars infected. Certain cultivars were found to be resistant to infection and preliminary work indicates that resistance may be inherited. Breeding for resistance may thus be possible. The rate and spread of the virus within inoculated plants was also established. Related Saccharum species and several grain crops were also found to be susceptible to the virus, but to date no weed hosts have been found.

Doug Gaskill, U. of HI. Doug discussed banana bunchy top virus (BBTV), which is vectored by the banana aphid in a persistent manner. The virus is widespread on Oahu, but not around Hilo on the island of Hawaii yet. Work is continuing on tissue culture systems, transformation, and regeneration of transgenic plants with resistance. Currently there are two lines that have remained symptom-free for 2 years. These were produced with a mutated REP gene of BBTV.

Diane Sether, U. of HI. Diane discussed the dreaded pineapple mealy bug wilt and the associated viruses (PMWaV) and the impact of this disease on the pineapple industry in Hawaii. Two closteroviruses have been associated with this disorder, which also requires the presence of the vector mealy bug for development of severe symptoms. Axillary and apical buds could be a source of virus-free plants for in vitro propagation and establishment of clean pineapple fields.

Eden Perez, U. of HI. Eden?s research focus is on the production of transgenic pineapple with resistance to PMWaV. Agrobacterium and gene gun-mediated approaches have been used. She also works on the evaluation of nematode resistance.

Mike Melzer, U. of HI. Mike presented information on the molecular characterization of PMWaV 1 and 2. Double-stranded RNA served as source material for RT-PCR amplifications and cloning. The viruses show some sequence similarities to other mealybug-transmitted closteroviruses, such as grapevine leafroll associated virus 3.

Wayne Borth, U. of HI. Wayne discussed his work on phytoplasma diseases of Dodonea and watercress. The Dodonea phytoplasma is related to Western X and the watercress yellows agent to aster yellows. Aster yellows phytoplasma has been detected infecting watercress on 11 farms on the island of Oahu. The aster leafhopper, M. quadrilineatus, has also been found at these farms. Both are recent introductions to the state of Hawaii, and together pose a significant threat to agriculture here.

Jim Crosslin, Washington State Univ.-Prosser. Jim discussed the work in Washington on peach latent mosaic viroid, grapevine viruses, and virus diseases of sweet cherry. Cherry leafroll virus and little cherry viruses 1, 2, and 3 are of increasing importance. The testing and therapy services of NRSP-5 for phytoplasmas and viroids were discussed.

Joseph Postman, USDA-ARS, Corvallis OR. The research Joseph discussed included evaluation of pear as a host of apple mosaic virus. The virus was not detected. Medlar was also tested as a host of apple chlorotic leafspot virus (ACLSV). Symptoms were produced on graft inoculated indicators. Other plants tested for viruses included Hawaiian strawberries, raspberries, and blueberries. Genetic resources of the collection being maintained at Corvallis were discussed. The virus indexing, virus therapy, and in vitro culture work we do at the USDA/ARS National Clonal Germplasm Repository helps to promote the improved national and international exchange of temperate fruit germplasm. Virus tested plant material is better able to obtain phytosanitary certification and meet the quarantine import regulations for the states and countries of germplasm requestors.

Annemiek Schilder, Michigan State Univ.

1) Virus screening of table grapes (T. Zabadal, A. Schilder, and J. Gillett [MSU]).
Tomato ringspot virus was found in declining table grape vines ?Marquis? and ?Vanessa? at the Southwest Michigan Research and Extension Center in Benton Harbor, MI, in 2000. The infection was confirmed with indicator plants and Ouchterlony double diffusion tests. These varieties were not known to be susceptible before. Dagger nematodes, Xiphinema spp., were also found in the soil at the site. An isolated mother block was established with selected vines from a noninfected site. Repeated testing has failed to detect any viruses in these plants and they now used for production of planting material. At the original site, experiments with ?Marquis? and ?Vanessa? on nematode-resistant rootstocks are underway. These vines are anticipated to remain virus-free.

2) Virus-tested blueberry program (P. Sood and R. Zinn [MDA]), and J. Gillett [MSU]).
Two blueberry nurseries in Michigan are participating in the virus-free certification program for blueberries. Under this program, mother blocks were screened by ELISA for five viruses (blueberry shoestring virus, blueberry leaf mottle virus, tomato ringspot virus, tobacco ringspot virus, and peach rosette virus). All samples were negative and the plants were certified to be virus-free.

3) Virus-tested tree fruit program (P. Sood and R. Zinn [MDA])
The MDA is also actively involved in improving the quality of pome and stone fruit trees in MI through indexing of nursery stock at Hilltop Nurseries, Inc. in Hartford, MI. The nursery maintains 12,600 stone and pome fruit trees in four scion-wood orchards for certification of bud wood for virus-free status. All trees were indexed or ELISA-tested or both for apple chlorotic leaf spot, apple stem grooving, apple stem pitting, green ring mottle, prune dwarf, and prunus necrotic spot viruses.

4) Survey for blueberry scorch and shock viruses (P. Sood and R. Zinn [MDA])
Leaf samples (200 total) from fifty blueberry fields in Michigan were tested by ELISA for the presence of blueberry scorch virus and blueberry shock ilarvirus, which are at present only known to occur in blueberry-growing areas in OR, WA, and BC, Canada. All samples turned out to be negative and it is therefore assumed that these viruses are not present in Michigan. A quarantine program was established for all blueberry planting stock coming into MI to help protect the Michigan blueberry industry from these viruses.

5) Plum pox virus detection and diagnostics (P. Sood and R. Zinn (MDA), and A. Jones [MSU]).
There are approximately 7,000 acres of stone fruit crops, excluding cherries, in MI. To help growers and crop consultants recognize plum pox virus, a Plum Pox Detection Guide was published and distributed. Inspections of peach, nectarine, apricot and plum orchards were carried out by the MDA as part of the National Plum Pox Virus Survey. Production, nursery, and research orchards were surveyed in 22 counties in Michigan in 2000 and 27 counties in 2001. In 2000, leaf samples from 34,638 trees were tested by USDA-approved ELISA for PPV strain D and other strains. In 2001, leaf samples from 92,484 trees were tested. All samples have been negative so far. Additional commercial orchards and nursery budwood trees will be tested for PPV in 2002. The MDA is currently working on a strategy to keep Michigan PPV-free.

6) Breeding cherries with resistance to viruses (A. Iezzoni [MSU], W. Howell [Washington]).
Selections from the MSU cherry dwarfing rootstock breeding program have been screened for resistance to prunus necrotic ringspot virus and prune dwarf virus in Prosser, WA. Several resistant genotypes have been identified.

7) Isolation and characterization of a transcriptional promoter from blueberry red ringspot virus (R. Allison, C. Mecey-Smith, and J. Gillett [MSU]).
The goal of this project is to isolate a promoter sequence from the DNA plant virus blueberry red ringspot virus (BRRV) for genetic modification of plants. The BRRV genome was cloned and sequenced. Seven promoter-like sequences were identified in the BRRV genome. Three of these were able to drive GFP expression in transgenic Arabidopsis thaliana, and one looked particularly promising. Currently, the other sequences are being tested for promoter activity. Assuming the promoter is functional as anticipated, it will be useful to University researches and licencees.

8) New fruit virology position
The Department of Plant Pathology at MSU has requested a faculty position with an emphasis on applied research with an emphasis on small and tree fruit viruses. It is expected that this position will be filled in the next two years.

Dennis Gonsalves, USDA, Pacific Basin Ag. Res. Center, HI. Dennis discussed the PPV survey currently underway in New York state, and evaluations of grape accessions for resistance to grapevine fanleaf virus (GFLV) and grapevine leafroll associated virus 3. Dennis has recently received a large grant for making transgenic papaya available to Third-world countries, such as Bangladesh, as a way of improving nutrition.

Gary Kinard, USDA, Beltsville, MD. Gary discussed the work of the Plant Germplasm Quarantine Office. In the last year the facility has intercepted numerous pathogens including several apple viruses and phytoplasmas. Some Prunus samples were also infected with peach latent mosaic viroid (PLMVd) and Prunus necrotic ringspot (PNRSV) and prune dwarf (PDV) viruses. Numerous Prunus, Malus, and Pyrus samples are currently undergoing therapy at the facility.

Dan Thompson, CFIA, Sydney, B.C. Dan?s presentation included information on host range studies of Canadian isolates of PPV. Prunus grandulosa was found to be a host. Tests were conducted to determine the best method of sampling for PPV detection in orchards. Distribution of PPV in infected trees was found to be erratic in some plum and peach trees. The national survey for PPV involved testing approximately 142,000 samples.

Roberto Michelutti, Ag. Canada, Harrow, Ont. Roberto discussed the detection of numerous viruses of strawberries and raspberries. Raspberry bushy dwarf (RBDV) and tobacco streak (TSV) viruses were found. Several latent viruses were detected in apples, including ACLSV, apple stem grooving (ASGV), and apple stem pitting (ASPV) viruses. Biological and serological detection methodologies were compared. The survey for viruses infecting soybeans was discussed. Bean pod mottle virus (BPMV) was found for the first time.

Deborah Golino, UC Davis. Deborah discussed the National Grapevine Importation Program and other activities of the Foundation Plant Materials Service (FPMS). The program includes stocks of grape, strawberry, pistachio, sweet potato, roses, and some Prunus. Grapes are tested and certified for GVFLV, TomRSV, GVLR, and corky bark, among other viruses. Custom PCR testing for several grape viruses are available. Tested and certified materials are available on a fee basis to nurseries, etc.

Adib Rowhani, UC Davis. Adib presented information on the detection of a new grapevine leafroll associated virus (GVLRaV-9). The presence of new graft-transmissible agents (GTAs) in the grape collection was discussed. Information on almond union mild etch (AUME), a genetic disorder, was presented. His research projects are focusing on characterizing of new viruses in grapevine or those which are partially characterized. This information will help in classification of the viruses under investigation and understanding of their etiology and epidemiology and their possible natural vectors. In addition, development of sensitive and reliable molecular methodologies for their detection will greatly facilitate their detection and elimination in commercially valuable material.

Bruce Kirkpatrick, UC Davis. Bruce discussed a wide range of research efforts on phytoplasmas and phytoplasma-induced diseases. Included were the genomic sequencing efforts on phytoplasmas and the Pierce?s disease organism, Xylella. The biology of vector species of leafhoppers was discussed.