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Poster: Biology & Disease Mgmt: Virology


Correlation of endogenous pararetrovirus with symptoms of citrus blight disease
A. ROY (1), J. Hartung (2), A. Stone (1), J. Sharo (2), R. Brlansky (3), W. Schneider (1) (1) USDA-ARS-FDWSRU, U.S.A.; (2) USDA-ARS-MPPL, U.S.A.; (3) University of Florida, CREC, U.S.A.

Citrus blight (CB) is a major economic problem in citrus groves in Florida. Even though the disease was first described in Florida in 1894 the causal agent of CB is still unknown. A number of biotic and abiotic agents have been postulated as potential causes of CB. CB occurs in a wide variety of locations with diverse environments and is root graft transmissible, suggesting that the disease is caused by a systemic infectious biotic agent. Recently, we documented a population of endogenous pararetrovirus (EPRV) sequences in a root stock susceptible to CB, carrizo citrange. Five EPRV sequences were obtained from healthy, huanglongbing (HLB)-infected and blight-affected carrizo citrange, but only one pararetrovirus sequence, termed Citrus blight associated pararetrovirus (CBaPRV), was found as RNA in all CB affected plants but not in any of the HLB diseased or healthy plants. To assess the correlation between active CBaPRV RNA and CB, samples from 8 healthy trees and 42 citrus trees diagnosed as blighted using the syringe injection technique were collected from four locations in Florida. Reverse transcription-PCR with primers specific to CBaPRV amplified the active RNA from CB affected roots, leaves, bark and flowers, but not from any healthy or HLB infected tissues. While there is no direct evidence that CBaPRV is the causal agent of blight, the presence of viral RNA is tightly correlated with CB symptoms.