Maintenance of mycoplasma‐like organisms occurring in Pyrus species by micropropagation and their elimination by tetracycline therapy

Pear explants ( Pyrus communis cv. Pine) infected with mycoplasma‐like organisms (MLOs) were maintained for more than 3 years by micropropagation on Murashige and Skoog medium supplemented with gibberellic acid, indole butyric acid and benzyl amino purine. MLOs reached consistently higher concentrations in micropropagated explants than in samples from field‐grown plants, although explants remained free from symptoms. MLOs could be eliminated by incorporation of 100/μg/ml oxytetracycline into the growth medium for a period of 4 weeks. These results have implications for plant propagation schemes of symptomless MLO‐infected explants raised by micropropagation.