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Title: Mild strain cross protection of tristeza: A review of research to protect against decline on sour orange in Florida and a look at the future

Author
item Lee, Richard
item Keremane, Manjunath

Submitted to: Frontiers in Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/14/2013
Publication Date: 9/6/2013
Citation: Lee, R.F., Keremane, M.L. 2013. Mild strain cross protection of tristeza: A review of research to protect against decline on sour orange in Florida and a look at the future. Frontiers in Virology. 4:259. DOI: 10.3389/frmicb.2013.00259.

Interpretive Summary: Florida has been the only location where Citrus tristeza virus (CTV) isolates have been selected for use to cross protect against the CTV decline occurring on sour orange rootstock. This article reviews the history of CTV in Florida, the value of sour orange rootstock, and summarizes the research directed towards selection of mild strains to slow or prevent loss of existing trees due to CTV induced decline on sour orange rootstock. The recent development of new technologies offers possibilities for better and quicker selection of desirable mild isolates of CTV for cross protection in the future, and this will be discussed.

Technical Abstract: Tristeza, caused by Citrus tristeza virus (CTV), has long been present in Florida, but outbreaks of decline on sour orange rootstock were occasional events until the late 1970s. Sour orange rootstock was valued for the high quality of fruit produced. Research was directed towards the selection and screening mild strains of CTV which could protect against sour orange decline strains. Following the introduction of Toxoptera citricida (also known as the brown citrus aphid [BrCA] in 1995, there was a greater concern for maintaining production of existing blocks of citrus on sour orange rootstock. Availability of the CTV genome sequence around the same time as well as molecular characterization of in planta CTV populations led to the selection of mild CTV isolates which, when inoculated into existing field trees, extended the productive life of the groves and enabled a more gradual replanting of trees on CTV-tolerant rootstocks. The history of CTV in Florida and the methods developed to select mild isolates for use for mild strain cross protection will be reviewed.