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ARS Home » Southeast Area » Fort Pierce, Florida » U.S. Horticultural Research Laboratory » Subtropical Insects and Horticulture Research » Research » Publications at this Location » Publication #183005
Title: VARIABILITY IN TRANSMISSION OF CITRUS TRISTEZA VIRUS ISOLATES FROM FLORIDA BY TOXOPTERA CITRICIDA

Author
item LEE, L - UNIV. OF FLORIDA
item Hunter, Wayne
item DAWSON, W.O. - UNIV. OF FLORIDA
item Hilf, Mark

Submitted to: American Phytopathological Society
Publication Type: Proceedings
Publication Acceptance Date: 6/28/2005
Publication Date: 8/1/2005
Citation: Lee, L., Hunter, W.B., Dawson, W., Hilf, M.E. 2005. Variability in transmission of Citrus tristeza virus isolates from Florida by Toxoptera citricida. American Phytopathological Society. July 30-August 3, 2005. Austin, TX. Paper No. P-494.

Interpretive Summary: Citrus tristeza virus (CTV) is an aphid transmitted plant infecting virus that continues to pose serious problems in the citriculture industries. To try and identify what factors may be influencing CTV transmission in Florida citrus, fifteen Florida isolates of CTV were tested for their transmissibility by the brown citrus aphid (Toxoptera citricida Kirkaldy) (BrCA). The BrCA is the major vector of CTV and has been shown to spread multiple stains of CTV. Strains of CTV referred to as ‘Genotypes’ were therefore evaluated for the efficiency of transmission by the BrCA. The T68 genotype of CTV, which was propagated by successive plant graft inoculation for 25 years, was readily transmitted by BrCA, with 45-80% of receptor plants becoming infected. However, another CTV isolate with the T36 genotype, which was propagated by successive graft inoculation for 30 years, was poorly transmitted by BrCA (3%). Furthermore, progeny virus from an infectious clone derived from the T36 genotype was also poorly transmitted by BrCA (<1%). In contrast, two other CTV isolates with T36 genotype, propagated from field trees infected within the previous 18 months, were moderately transmitted by BrCA (25-30%). The CTV isolate with the VT genotype, which had been propagated by successive graft inoculation for 11 years, was not transmitted by BrCA, while two other CTV isolates with the VT genotype propagated from recently infected field trees, were moderately transmitted by BrCA (23-36%). These results indicate that virus transmission by BrCA is variable among CTV isolates from Florida. While our data indicates that the isolate genotype and the time spent in graft propagation without transmission by an aphid may play a role in maintaining virus spread, no single factor examined appears to be a specific indicator for virus transmission efficiency by BrCA.

Technical Abstract: Citrus tristeza virus (CTV) is an aphid transmitted plant infecting virus that continues to pose serious problems in the citriculture industries. Fifteen Florida isolates of CTV were tested for their transmissibility by the brown citrus aphid (Toxoptera citricida Kirkaldy) (BrCA). The BrCA is the major vector of CTV and has been shown to spread multiple stains of CTV. A CTV isolate with the T68 genotype, propagated by successive graft inoculation for 25 years, was readily transmitted by BrCA, with 45-80% of receptor plants becoming infected. However, another CTV isolate with the T36 genotype, which was propagated by successive graft inoculation for 30 years, was poorly transmitted by BrCA (3%). Furthermore, progeny virus from an infectious clone derived from the T36 genotype was also poorly transmitted by BrCA (<1%). In contrast, two other CTV isolates with T36 genotype, propagated from field trees infected within the previous 18 months, were moderately transmitted by BrCA (25-30%). The CTV isolate with the VT genotype, which had been propagated by successive graft inoculation for 11 years, was not transmitted by BrCA, while two other CTV isolates with the VT genotype propagated from recently infected field trees, were moderately transmitted by BrCA (23-36%). These results indicate that virus transmission by BrCA is variable among CTV isolates from Florida. While our data indicates that the isolate genotype and the time spent in graft propagation without transmission by an aphid may play a role in maintaining virus spread, no single factor examined appears to be a specific indicator for virus transmission efficiency by BrCA.