Articles
CONTAMINATION AND ITS IMPACT IN TISSUE CULTURE
Article number
560_66
Pages
353 – 359
Language
English
Abstract
Tissue culture contamination frequently originates with the introduction into culture of explants contaminated with endophytic micro-organisms or surface sterilisation-resistant micro-organisms e.g. in biofilms.
These include pathogens of the plant and common environmental micro-organisms, both of which may become pathogenic in culture (‘vitropaths’). Heterotrophic plant tissue media are capable of supporting the growth of many common environmental micro-organisms.
The latter may provide a food source for micro-arthropods, which can act as vectors in the spread of laboratory contamination.
Cultivable micro-organisms may over-run the cultures killing the explants; or inhibited by media components, may remain latent until the medium is changed to become vitropaths; yet other expressed micro-organisms may not visibly affect the growth of the cultures.
Some micro-organisms may positively influence plant growth and development by acidification of the medium or by release of plant growth regulators.
Conversely, some micro-organisms are inhibited by acidification of culture media and by exudates from the plant tissues and may be weakly expressed or latent as endophytes in the tissues.
The release of contaminated plants in the environment brings with it the risk of large-scale disease and/or poor plant performance in the field.
The best strategy to control tissue culture contamination is to establish aseptic cultures and to maintain good laboratory practice, including routine testing for contamination by cultivable micro-organisms and micro-arthropods.
Pathogen testing should follow official guidelines, for example, as laid down by the European and Mediterranean Plant Pathology Organisation (EPPO: http://www.eppo.org). Microplants, as a consequence of a sub-optimal production process, may be prone to weaning stress and damping-off diseases post vitrum. Microplants from autotrophic tissue cultures (aseptic ‘microhydroponic cultures’) may be physiologically more mature and show greater constitutive disease-resistance than those from mixotrophic or heterotrophic culture.
Autotrophic cultures do not support high levels of contamination with micro-organisms and may be used to rescue contaminated cultures.
More importantly, they can be inoculated with selected beneficial mycorrhizal and bacterial isolates, singly and in combination, to improve microplant stress tolerance at weaning and improve resistance to damping-off diseases.
Here, the principles of microbial contamination management are discussed and the opportunities for biotization and treatment of microplants with elicitors of disease resistance to protect them against weaning stress and damping-off diseases, and against biotic and abiotic field stresses, are discussed.
These include pathogens of the plant and common environmental micro-organisms, both of which may become pathogenic in culture (‘vitropaths’). Heterotrophic plant tissue media are capable of supporting the growth of many common environmental micro-organisms.
The latter may provide a food source for micro-arthropods, which can act as vectors in the spread of laboratory contamination.
Cultivable micro-organisms may over-run the cultures killing the explants; or inhibited by media components, may remain latent until the medium is changed to become vitropaths; yet other expressed micro-organisms may not visibly affect the growth of the cultures.
Some micro-organisms may positively influence plant growth and development by acidification of the medium or by release of plant growth regulators.
Conversely, some micro-organisms are inhibited by acidification of culture media and by exudates from the plant tissues and may be weakly expressed or latent as endophytes in the tissues.
The release of contaminated plants in the environment brings with it the risk of large-scale disease and/or poor plant performance in the field.
The best strategy to control tissue culture contamination is to establish aseptic cultures and to maintain good laboratory practice, including routine testing for contamination by cultivable micro-organisms and micro-arthropods.
Pathogen testing should follow official guidelines, for example, as laid down by the European and Mediterranean Plant Pathology Organisation (EPPO: http://www.eppo.org). Microplants, as a consequence of a sub-optimal production process, may be prone to weaning stress and damping-off diseases post vitrum. Microplants from autotrophic tissue cultures (aseptic ‘microhydroponic cultures’) may be physiologically more mature and show greater constitutive disease-resistance than those from mixotrophic or heterotrophic culture.
Autotrophic cultures do not support high levels of contamination with micro-organisms and may be used to rescue contaminated cultures.
More importantly, they can be inoculated with selected beneficial mycorrhizal and bacterial isolates, singly and in combination, to improve microplant stress tolerance at weaning and improve resistance to damping-off diseases.
Here, the principles of microbial contamination management are discussed and the opportunities for biotization and treatment of microplants with elicitors of disease resistance to protect them against weaning stress and damping-off diseases, and against biotic and abiotic field stresses, are discussed.
Authors
A.C. Cassells
Keywords
Agrobacterium, biotization, in vitro culture, meristem culture, pathogen elimination
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