Recovery - complete remission of disease symptoms - has been reported in plants affected by phytoplasmas. The physiological basis for this phenomenon is not yet understood, but it seems associated to ultrastructural and biochemical modification of the phloem, the tissue where phytoplasmas live and spread. In this work we compared asymptomatic, phytoplasma-infected and recovered apple and grapevine leaf tissues by means of ultrastructural and gene-expression analyses, focusing on a possible role of specific phloem proteins in the plant defense-related processes. Preliminary results indicate that different occlusion mechanisms could interact in the phloem during phytoplasma symptomatic status and/or recovery.
