Progress 10/01/03 to 09/30/09
Outputs
OUTPUTS: Research on the potential role of graft-transmissible agents in the bloom delay associated with the use of Ta Tao 5 germplasm was continued. Peach latent mosaic viroid (PLMVd), Apple chlorotic leaf spot virus (ACLSV), and Asian Prunus virus 1 (APV-1) had been detected in Ta Tao 5. Heat-treatment of Ta Tao 5 germplasm eliminated both the bloom delay and PLMVd and ACLSV. APV-1 was detected in heat-treated germplasm of Ta Tao 5 but no bloom delay was observed in these trees. Earlier work indicated that bloom delay was associated with the presence of PLMVd but the presence of ACLSV was not associated with the observed bloom delay. However, sources of PLMVd other than that found in Ta Tao 5 did not produce a bloom delay suggesting the possibility that another graft-transmissible agent may be involved in the bloom delay phenomenon. The isolate of ACLSV in Ta Tao 5 was shown to be distinct from other isolates of the virus requiring a change in PCR assayed used to detect the virus. This isolate of APV-1 was completely sequenced providing the first description of the complete genome of an isolate of APV. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Identification of the graft-transmissible agent(s) controlling the bloom delay and knowledge of their epidemiology would allow growers to use selective inoculation with an individual agent to produce the bloom delay. At the same time the presence of other agents not associated with the bloom delay but which might interact with other graft-transmissible agent already present in trees in an orchard would be eliminated. Controlling virus diseases of temperate fruit tree crops is usually completed through the planting of trees propagated from virus-tested sources of budwood. As our knowledge of graft-transmissible diseases in fruit tree crops increases, it becomes clear that the presence of some agents are beneficial to the tree and the optimal yield and life expectancy of an orchard may require the presence of a particular agent. Bloom delay in SC reduces the period during which orchards are at risk from late spring freezes which have caused significant crop losses/failures over the past 5 years.
Publications
- Marini,D.B., Gibson,P.G., and Scott,S.W. 2009. The complete nucleotide sequence of an isolate of Asian prunus virus 1 from peach [Prunus persica (L) Batch]. Archives of Virology 154:1375-1377.
- Marini,D.B., Gibson,P.G., and Scott,S.W. 2008. The complete nucleotide sequence of an isolate of apple chlorotic leaf spot virus from peach (Prunus persica (L.) Batch). Archives of Virology 153: 1003-1005.
- Gibson , P.G. Reighard, G.L. Scott, S.W., and Marini, D. 2008. Phenotypical Variation in Peach Trees Inoculated with Defined Mixtures of Viruses and Peach Latent Mosaic Viroid. Acta Horticulturae 781:541-546
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: Research on the potential role of a foveavirus in the bloom delay associated with the use of Ta Tao 5 germplasm was continued. The foveavirus was identified as Asian prunus virus (APV), however, it is not yet confirmed whether it is APV 1, APV2 or APV 3. There was no bloom delay in trees which had been propagated from heat-treated germplasm of Ta Tao 5 even though APV was detected in them. Continued to serve as technical representative to NRSP-5 for the southern region experiment stations. Selected as vice-chairman of the Tier 2 committee of the Fruit Tree National Clean Plant Network one of the break-out groups and presenting the findings of the group on May 9 PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Ta Tao 5 germplasm has been reported to be infected by 3 agents: Asian prunus virus (APV), Peach latent mosaic viroid (PLMVd), and apple chlorotic leaf spot virus (ACLSV). The absence of bloom-delay in heat-treated Ta Tao 5 in which the presence of APV has been detected suggests that APV is not involved in the bloom delay. Other work relating the presence of bloom delay to the presence of Peach latent mosaic viroid (PLMVd) and apple chlorotic leaf spot virus (ACLSV) indicates that the bloom delay is associated with the presence of PLMVd. The presence of ACLSV is not associated with the observed bloom delay. Knowledge of the agent causing the bloom delay would allow growers to inoculate trees with that agent and then manage orchards to minimize the spread of the agent to adjacent plantings.
Publications
- No publications reported this period
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Progress 01/01/07 to 12/31/07
Outputs
Research on the potential role of a foveavirus in the bloom delay associated with the use of Ta Tao 5 germplasm was continued. Two trials involving the cultivars Juneprince and Springprince inoculated with mixtures of PLMVd, ACLSV, and the foveavirus have been established and data on pomological traits and the infection statuse of individual trees are being recorded. Continued to serve as technical representative to NRSP-5 for the southern region experiment stations. Participated in the work shop for the National Clean Plant Network to be held in Beltsville, May 8-9, 2007, serving as chairman of one of the break-out groups and presenting the findings of the group on May 9.
Impacts
The value of clean stock programs continues to be demonstrated. The southeastern budwood program now contains blocks of trees established with indexed budwood from the system. These blocks have been tested for 6 years and there is no indication of the presence of the 3 viruses (Prunus necrotic ringspot virus (PNRSV),Prune dwarf virus (PDV) and Plum pox virus) which are tested for under the program. This is in spite of some blocks being adjacent to other cultivars infected with PNRSV and/or PDV.
Publications
- No publications reported this period
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Progress 01/01/06 to 12/31/06
Outputs
Research on the potential role of a foveavirus in the bloom delay associated with the use of Ta Tao 5 germplasm was continued. This virus was also detected in other peach germplasm originating from China. Initial data from a trial of the cultivar Springprince inoculated with mixtures of PLMVd, ACLSV, and the foveavirus show differences among treatments but there are as yet no consistent differences. Continued to serve as technical representative to NRSP-5 for the southern region experiment stations. Participated in the discussion leading to the work shop for the National Clean Plant Network to be held in Beltsville, May 8-9, 2007.
Impacts
Establishment of a national clean stock program will be of immense value to the nursery and production industries associated with fruit crops. The value of such a program is further underlined by the discovery of Plum pox virus in 2 additional states in the US. The knowledge we have gained about the detection of ACLSV, and the foveavirus in Ta Tao 5 will allows us to establish a reliable detection system (PCR) for these two viruses in this and other germplasm.
Publications
- No publications reported this period
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Progress 01/01/05 to 12/31/05
Outputs
Attended annual meeting of NRSP-5 as technical represenative for the southern region held in Raleigh, North Carolina, May 19, 2005. Continued research on the potential role of a foveavirus (identified as Asian prunus virus 1 by Candresse) in the bloom delay associated with the use of Ta Tao 5 germplasm. This virus was also detected in other peach germplasm originating from China.
Impacts
Establishment of a national clean stock program will be of immense value to the nursery and production industries associated with fruit crops.
Publications
- No publications reported this period
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Progress 01/01/04 to 12/31/04
Outputs
Participated as Southern Region technical representative to the NRSP-5 project. Attended annual meeting on May, 20, 2004 in Davis, California. Have been working with Director Ken Eastwell in an effort to set up an alternative funding source for the project linked to other clean stock programs (CA,PA, and MD).
Impacts
Establishment of a national clean stock program will be of immense value to the nursery and production industries associated with fruit crops.
Publications
- No publications reported this period
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