Agricultural and horticultural crops worldwide are threatened by various diseases, from which several important ones are caused by bacteria. Bacterial infections can result in a great variety of symptoms such as wilting, leaf spot, cankers and bacterial rot.
Bacterial diseases are feared especially by propagators because the pathogen can be symptomless present in plant material,till the environment becomes suitable for multiplication of the pathogen and symptom expression In addition, few possibilities are available to combat bacterial infections in plants. Prevention therefore plays an important role in the control of bacterial diseases. For this purpose, diagnostic methods are needed so that bacteria can be detected at an early stage. In addition, knowledge of the biology of the pathogen is required to prevent contamination of plant material and spread of the disease.
For the development of the diagnostic methods, the newest DNA/RNA technologies are used. Entire genome sequences are studied, and specific sequences are selected for the development of molecular tests, such as on-site assays with which the pathogen can be quickly and reliably identified in the field. Molecular methods are also being developed which can distinguish dead bacteria from living ones. This is important to ascertain the effect of treatments intended to kill bacteria in plant material.
Biology of the pathogen
Research into the biology of the pathogen focuses on the way in which it spreads: airborne, via tools and machinery, or in the soil. To answer the question of how the pathogens enter and colonise the plant, bacteria are labelled with a green fluorescent protein (GFP) to make them visible under the microscope. Research is also being conducted into possibilities for improving hygiene protocols. This research looks at the efficacy of biocides for decontaminating materials and for controlling pathogens on and in materials and in the plant itself.
Effective control agents
To control pathogens in the plant, a search is being conducted for bacteria that colonise plants systemically (known as endophytes). Research is also being conducted into indicators for the resilience of cultivation systems. This involves the analysis of not only the physicochemical properties but also of populations of microorganisms (the microbiome) of substrates and plant material.
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