Submitted to: International Society of Citriculture Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 12/15/2000
Publication Date: 7/15/2003
Citation: KRUEGER, R., BALLANCE, P.M., KAHN, T.L., BIER, O.J., GUMPF, D.J., BASH, J.A. SHOOT-TIP MICRO-GRAFTING FOR RESCUE OR THERAPY OF FIELD-GROWN CITRUS GERMPLASM ACCESSIONS. INTERNATIONAL SOCIETY OF CITRICULTURE PROCEEDINGS. 2003. Interpretive Summary: Germplasm accessions for perennial crops are often maintained in field collections and are thus vulnerable to loss from environmental and phytopathological factors. This necessitates re-propagation. If a protected back-up accession is not available, the propagative material must often be taken from a field tree. Sometimes propagative materials obtained in this way are not of high quality and re-propagation is difficult. This paper describes the use of shoot-tip micrografting for re-propagation of a declining field tree that it was not possible to repropagate by conventional means. The micrografting procedure is somewhat skill-intensive and is thus not normally used for propagation except in cases where elimination of pathogens is desired (its main utilization). However, in this case it proved to be the only way to save the accession and its use for this purpose should be considered when appropriate.
Technical Abstract: Shoot-tip micro-grafting (STG) is a well-established technique for the potential elimination of virus and viroid pathogens from citrus germplasm. It is generally utilized in quarantine and certification programs using small trees maintained under glass or screen. A modified STG procedure utilizing shoot-tips from a declining field-grown tree was used to produce a replacement tree. It had not been possible to propagate the tree by budding or other conventional techniques. Since the source tree subsequently died, the modified STG procedure allowed the rescue of an accession that would otherwise have been lost. An additional benefit was the apparent elimination of a viral pathogen: the source tree had previously tested positive for Citrus Tristeza Virus, while the replacement tree tested negative.