Diagnostic Techniques for early detection of phytoplasmas diseases

Abstract

Phytoplasmas are wall-less, non-culturable, phloem-limited bacterial pathogens that belong to the Mollicutes. They cause many diseases in lots of plant species (wild and cultivated) belonging to many different plant families, resulting in significant losses in important crops, and economically damaging epidemics worldwide. Phytoplasmas infect major cultivated crops such as many annual crops, fruit trees, grapevines and palms, which makes control of these diseases a priority, and the first important step for management is efficient and effective phytoplasma diagnosis. Detection of phytoplasmas is difficult because of their irregular distribution within the diseased plants and low concentration inside infected plants. In the last two decades most research toward the detection of phytoplasmas has used nucleic acid-based techniques such as PCR, which is used to amplify regions of phytoplasma genomes existing inside infected plants. However, most routine diagnostics has moved from general PCR to real-time PCR, due to the improved sensitivity and reduced risk of contamination due to the use of a closed system for product detection. Also the method can be developed into a semi-quantitative method.