Actinomycetes: The Causative Agents of Plant Diseases
Actinomycetes are a group of microorganisms that were previously thought to be fungi, but are now classified as bacteria due to their unique features. They have a thin branching mycelium and can produce antibiotics. However, some species of actinomycetes are also able to cause plant diseases, such as the common scab of potato tubers and scab of beet roots. This article discusses the structure, development, and consequences of actinomycetes as causative agents of plant diseases.
Actinomycetes are unique microorganisms that have characteristics of both bacteria and fungi. They have a thin branching mycelium that resembles the mycelium of some fungi, but unlike fungi, they do not have partitions and their cells do not have a pronounced nucleus, making them resemble bacteria. In addition, some species of actinomycetes have the ability to produce antibiotics.
However, not all species of actinomycetes are beneficial. Some have adapted to a parasitic existence on plants and animals, causing diseases like actinomycosis. Among the phytopathogenic actinomycetes, species of the genus Streptomyces are of great interest as they cause scab in plants.
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The most well-known plant disease caused by actinomycetes is the common scab of potato tubers and scab of beet roots. Potato scab caused by Streptomyces scabies develops on tubers during the growing season of potatoes, resulting in cracks, small warts, corking of the affected tissue, and ulcers formation. In severe cases, the ulcers merge, and the entire tuber is covered with scab. These actinomycetes accumulate in the soil and remain on the affected tubers, cracks, and ulcers.
To protect crops from actinomycosis, it is important to implement techniques that prevent the accumulation of phytopathogenic species in the soil. Crop rotation with the removal of the affected crop from the field for several years and alternation of crops in crop rotation are effective measures to regulate the quantitative composition of actinomycetes. These methods reduce the amount of infection in the soil due to the effect of root secretions on its microflora.
In conclusion, actinomycetes have both beneficial and harmful effects on plants. While some species can produce antibiotics and are used for various purposes, others can cause plant diseases such as the common scab of potato tubers and scab of beet roots. Effective techniques such as crop rotation and alternation of crops can help to prevent the accumulation of phytopathogenic actinomycetes in the soil, thus reducing the incidence of plant diseases.