Effect of altered levels of oxygen and carbon dioxide on phytoplasma abundance in Oenothera leaftip cultures

• Published in: Physiological and molecular plant pathology 1997-04, Vol.50 (4), p.275-287
• Main Authors: SEARS, B. B, KLOMPARENS, K. L, WOOD, J. I, SCHEWE, G
• Format: Article
• Language: English
• Subjects: Bacterial plant pathogens; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Pathology. Damages, economic importance; Phytopathology. Animal pests. Plant and forest protection
• ISSN: 0885-5765; 1096-1178
• DOI: 10.1006/pmpp.1997.0086

Phytoplasmas reach higher titres in leaftip cultures of Oenothera elata, than in infected field or greenhouse grown plants. Differences in the physiology of the host are probably responsible for the differential proliferation of the phytoplasma. Investigations were undertaken to determine if reduced photosynthetic activity, resulting in a reduction in internal levels of oxygen, was responsible for the high titres of phytoplasma in the Oenothera leaftip cultures. To test whether phytoplasmas are sensitive to oxygen concentration, healthy and phytoplasma infected Oenothera cultures were grown under conditions of varying levels of O sub(2) or CO sub(2) mixed in air. Southern blots failed to show a consistent correlation between atmospheric conditions and phytoplasma abundance, as measured using a genomic probe. Variations in plasmid band stoichiometry were observed in one strain in the different atmospheric conditions, but similar variability was found for the air-grown controls. To determine if the O sub(2) generated by photosynthesis would affect phytoplasma growth, photosynthetic mutants of phytoplasma infected Oenothera leaftip culture plants were isolated and compared with photosynthetically-competent controls. Southern hybridizations indicated that the photosynthetic mutants tended to have higher titres of phytoplasma, indicating that the pathogen is more successful in non-photosynthetic tissue.