ISHS Acta Horticulturae 530: International Symposium on Methods and Markers for Quality Assurance in Micropropagation
QUALITY ASSURANCE SYSTEMS FOR PLANT CELL AND TISSUE CULTURE; THE PROBLEM OF LATENT PERSISTENCE OF BACTERIAL PATHOGENS AND AGROBACTERIUM-BASED TRANSFORMATION VECTOR SYSTEMS |
| Author: | C. Leifert |
| Abstract:
Contaminants may be introduced with the explant or during manipulations in the laboratory or by animal vectors (Leifert et al., 1994a; 1991a; Berger et al., 1992). Contaminants may express themselves immediately or can remain latent for long periods of time (Leifert et al., 1994a; Leifert and Waites, 1992; Cooke et al., 1992). This often makes it difficult to identify the source of contamination. It is extremely difficult to eliminate bacterial and fungal pathogens from established plant tissue cultures using antibiotics, fungicides and other biocides. In many cases treatments only inhibit contaminants and low levels of contamination persist. In particular, the use of antibiotics against Gram negative bacteria (including Agrobacterium tumefaciens vector systems used in genetic engineering) was frequently shown to be extremely difficult or unsuccessful. Hazard Analysis Critical Control Point (HACCP) systems are therefore now used in many commercial plant tissue culture and micropropagation laboratories (Leifert and Woodward, 1998; Leifert et al., 1994a) which aim at preventing contamination at sources. Detection of latent contamination may involve the use of general and semi-selective microbial growth media or serological and PCR-based molecular techniques for specific pathogens. It is often impossible to detect low numbers of latent bacterial contaminants (e.g. levels present following antibiotic treatment or when acidified plant media are used). This poses a particular risk in the production of transgenic plants where neither the elimination or detection of Agrobacterium tumefaciens-based vector systems can be guaranteed with the currently available methodologies. | |
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