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Title: TRANSMISSION OF PRUNUS NECROTIC RINGSPOT VIRUS INTO THREE PEACH CULTIVARS, MEASURED BY RNA HYBRIDIZATION FOLLOWING IN VITRO MICROGRAFTING

Author
item HEUSS, K - UNIV OF NEBRASKA
item LIU, Q - CHINA
item Hammond, Rosemarie
item HAMMERSCHLAG, FREDDI

Submitted to: Acta Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/30/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Prunus necrotic ringspot ilarvirus (PNRSV) is common in many Prunus species and causes substantial reduction in growth and yield in peach. Certain cultivar-region combinations have a higher incidence of PNRSV than others, suggesting that some cultivars may be more susceptible to the virus than others because of their genetic background. Previous studies in our laboratories have demonstrated that in vitro micrografting of cultured peach shoots was a reliable and efficient method for transmission of PNRSV across grafts and suggested that such a system could be used to measure resistance of germplasm, including germplasm engineered for resistance to PNRSV, to virus infection. In this study, we have extended our prior results to include evaluation of the resistance of mutiple cultivars to PNRSV infection. All cultivars tested appeared to be equally susceptible to the virus. The technique will be of value to scientists interested in rapid method for the year-round screening of peach germplasm for resistance to PNRSV.

Technical Abstract: As part of our program to develop transgenic peach cultivars with improved disease resistance, we showed that grafting of in vitro cultured "Suncrest" peach [Prunus persica (L.) Batsch] tips onto decapitated stems of prunus necrotic ringspot virus (PNRSV)-infected "Suncrest" shoot cultures, resulted in consistent transfer of virus across grafts as demonstrated by RNA hybridization analysis, suggesting that such a system could be useful for measuring resistance to PNRSV in peach shoot cultures (Huess-LaRosa et al., 1995). We have extended these studies to include grafts of "Springcrest" and "Nemaguard" test tips onto "Suncrest" stocks. RNA hybridization analysis showed that PNRSV persists in shoot cultures for 18 months after initiation from PNRSV-infected "Suncrest" trees and after 16 weeks of treatment at 4 C in the dark, suggesting that a supply of infected shoot cultures could be maintained for repeated use. Graft success for grafts of "Springcrest" onto "Suncrest" and "Nemaguard" onto "Suncrest", equalled or exceeded success rates for "Suncrest" onto "Suncrest". Virus was transmitted from infected stocks to "Suncrest", "Springcrest", and "Nemaguard" test tips by two weeks in most successful micrografts. There was no significant difference in the virus concentrations among the three scions at two, four, and six weeks after grafting, suggesting that there is equal efficacy of virus transfer through grafts from "Suncrest" to the three cultivars, and that no differences in resistance to PNRSV exist among these cultivars.