Phytoplasmas: bacteria that manipulate plants and insects.
Saskia A Hogenhout1, Kenro Oshima, El-Desouky Ammar
1Department of Disease and Stress Biology, The John Innes Centre, Norwich Research Park, Colney Lane, Colney, Norwich, Norfolk NR4 7UH, UK. saskia.hogenhout@bbsrc.ac.uk
Molecular Plant Pathology
|August 19, 2008
Summary
Phytoplasmas are plant pathogens transmitted by insects, causing significant agricultural damage. Current control methods like insecticides and plant removal are insufficient, with limited resistant cultivars available.
Area of Science:
- Plant Pathology
- Insect-borne Diseases
- Microbiology
Background:
- Phytoplasmas are obligate intracellular bacteria within the genus Candidatus (Ca.) Phytoplasma.
- They belong to the phylum Firmicutes and are characterized by their lack of a cell wall.
- Phytoplasmas are primarily transmitted by insect vectors and infect a wide range of plant species.
Purpose of the Study:
- To provide a comprehensive overview of phytoplasmas, including their taxonomy, host range, and disease symptoms.
- To discuss current disease control strategies and their limitations.
- To highlight the impact of phytoplasmas on agriculture and plant health.
Main Methods:
- Phylogenetic analysis based on 16S rRNA gene sequences to classify phytoplasmas into distinct clades.
- Review of literature on phytoplasma life cycles, transmission by insect vectors, and plant-insect interactions.
- Compilation of documented disease symptoms in plants and effects on insect vectors.
Main Results:
- Approximately 30 phytoplasma clades have been identified, with Ca. Phytoplasma asteris (16SrI group) being widespread.
- Phytoplasmas infect over 80 monocot and dicot plant species and are transmitted by around 30 insect species.
- Observed plant symptoms include witches' broom, phyllody, virescence, stunting, and phloem necrosis.
Conclusions:
- Phytoplasmas pose a significant threat to global agriculture due to their broad host range and effective insect transmission.
- Current control measures, including insecticide application and removal of infected plants, are often inadequate.
- The development of phytoplasma-resistant plant cultivars is crucial for effective long-term disease management.
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