Articles
PLANT TISSUE CULTURES UBIQUITOUSLY HARBOR ENDOPHYTIC MICROORGANISMS
Article number
865_29
Pages
231 – 239
Language
English
Abstract
Plant tissue cultures are normally considered to be aseptic, which literally means freedom from all microorganisms.
Contrary to this basic assumption, evidence is now emerging that in vitro plant cultures almost ubiquitously harbor endophytic microorganisms, particularly bacteria that are not detected through general visual examination.
Investigating the cause of the unexplained degeneration and decline in the performance of in vitro cultures of different horticultural crops including banana, grape, papaya, watermelon, capsicum, eggplant, chrysanthemum, gerbera, etc. we have elucidated the rampant association of diverse bacteria covertly associated with such stocks.
A three-step screening procedure was developed for the detection of such unsuspecting but covert bacteria-harboring cultures, including diligent visual examination, indexing of medium and of tissue.
Further studies aimed at identifying cultures that are clean by resorting to systematic monitoring of freshly initiated apparently clean stocks through regular indexing revealed the presence of endophytic bacteria that are not normally amenable for cultivation as brought out through molecular screening with microscopic validation.
The observations with the in vitro stocks of diverse plants, substantiated by the findings reported from other laboratories now suggest that the so called axenic cultures ubiquitously harbor endophytic bacteria in covert or non-cultivable forms and that the cultures are at best free from obviously hazardous organisms.
Such associations, however, may have varying effects on the performance of the in vitro stocks, morphogenesis, long-term maintainability of stocks, in vitro conservation, and plant performance during acclimatization and post acclimatization.
These findings have implications in all aspects of plant biology and various tissue culture applications.
Contrary to this basic assumption, evidence is now emerging that in vitro plant cultures almost ubiquitously harbor endophytic microorganisms, particularly bacteria that are not detected through general visual examination.
Investigating the cause of the unexplained degeneration and decline in the performance of in vitro cultures of different horticultural crops including banana, grape, papaya, watermelon, capsicum, eggplant, chrysanthemum, gerbera, etc. we have elucidated the rampant association of diverse bacteria covertly associated with such stocks.
A three-step screening procedure was developed for the detection of such unsuspecting but covert bacteria-harboring cultures, including diligent visual examination, indexing of medium and of tissue.
Further studies aimed at identifying cultures that are clean by resorting to systematic monitoring of freshly initiated apparently clean stocks through regular indexing revealed the presence of endophytic bacteria that are not normally amenable for cultivation as brought out through molecular screening with microscopic validation.
The observations with the in vitro stocks of diverse plants, substantiated by the findings reported from other laboratories now suggest that the so called axenic cultures ubiquitously harbor endophytic bacteria in covert or non-cultivable forms and that the cultures are at best free from obviously hazardous organisms.
Such associations, however, may have varying effects on the performance of the in vitro stocks, morphogenesis, long-term maintainability of stocks, in vitro conservation, and plant performance during acclimatization and post acclimatization.
These findings have implications in all aspects of plant biology and various tissue culture applications.
Publication
Authors
P. Thomas
Keywords
endophytic bacteria, micropropagation, microbial contamination, bacterial identification, indexing, banana, grape, papaya, watermelon, chrysanthemum
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