Small RNA analysis reveals different profiles among ‘Candidatus Phytoplasma mali’ strains in Malus x domestica cultivar Golden Delicious in vitro plants

In plant hosts phytoplasmas were shown to affect the expression of a broad range of genes and RNA regulatory molecules acting at a post-transcriptional level and leading to changes in several metabolic pathways. Effector proteins secreted by phytoplasmas play a paramount role in the metabolic changes resulting in disease symptoms development. It is shown here that in ‘Candidatus Phytoplasma mali’-infected in vitro plants of Malus x domestica cultivar Golden Delicious another class of pathogen-derived molecules represented by small RNA can be detected through specific sequencing. The profiles obtained from seven different phytoplasma strains revealed differences that could be associated to their capacity to multiply in the plant host or due to differences in the expression level of the phytoplasma transcripts.