Phytoplasma effectors and pathogenicity factors

For the study and the management of phytoplasma-associated diseases, the most relevant knowledge needed is the one related to their pathogenicity. After the availability of full and draft genome sequences of some of the phytoplasmas, a mining search allowed identifying a number of possible virulence factors. Their possible pathogenic action was verified mainly by their expression in transgenic plants such as Arabidopsis spp. and Nicotiana spp. Several possible pathogenicity factors such as TENGU and SAP11 and/or effector molecules were shown to be related to metabolic and or phenotypic modifications indistinguishable from those present in the phytoplasma-infected plants such as phyllody and witches\u2019 broom. The possible pathogenicity factors or disease effectors studied enclosing extrachromosomal DNAs, phloem structural modifications, and very recently miRNAs are also described