Practice Abstract 17

Plant pathogens are identified in very different ways – visually, based on expert experience and knowledge, and in the laboratory – by performing morphological analyses of the pest, or using biotechnological tools, more often used for fungal and bacterial pathogens, but possible also for pests. The simplest and oldest laboratory method is to cultivate the pathogen on the medium, followed by microscopic analysis of the medium and identification of the pathogen by its morphological characteristics. In recent decades, with the development of biotechnology, molecular methods have been introduced in the diagnosis of plant pathogens. Nucleic acid (NA) analysis methods are the most accurate and fastest. They are most often based on polymerase chain reaction (PCR), a highly sensitive technology where DNA detection is possible even from a few pathogen spores. During the PCR, specific fragments of the sample genome unique to the pathogen are amplified. Visualization of molecular reactions is performed using electrophoresis to separate DNA fragments on an agarose gel, followed by DNA luminescence and comparison with specific markers. This method is usually the most accurate and relatively fast, but its technological complexity makes it expensive due to the need to use advanced laboratory equipment as well as expensive reagents. In addition, these analyses require specific knowledge and experience.