Europe is the world’s main producer and exporter of grapevine planting material and wine. This very important sector for Slovene and Austrian economy is facing epidemic threats of several GYs caused by taxonomically unrelated phytoplasmas. In Europe, the main GYs are the widespread “bois noir” associated with the presence of ‘CandidatusPhytoplasma solani’ (BNp) from the ribosomal group 16SrXIIA and “flavescence dorée”,associated with the presence of quarantine phytoplasmas belonging to 16SrV (FDp). BN became one of the most important grapevine diseases, with the infection rates reaching 50–80% in some areas during the last 15 years. In addition, because BNp causes the same symptoms on the grapevine as FDp, presumably by similar mechanisms, we will use it as a working model to avoid research problems associated with the quarantine status of FDp.

Specific objectives of the proposed project

  • to determine a possible route of propagation of BNp strains and the influence of various ecological conditions in vineyards on the presence and fluctuation of particularstrain, as well as disease development in Slovenia and Austria;
  • to prepare a collection of FDp strains in C. roseus in addition to an expanding existed BNp strain collection for following and comparison of symptom development in host plant at the phenotypic, genome, transcriptome and metabolome level and to establish the axenic cultures of FDp and BNp;
  • to gain knowledge on the overall BNp strain and corresponding effector variability by performing highthroughput sequencing of grapevine and C. roseus infected with different strains of BNp;
  • to find potential effector proteins secreted through the Sec protein translocation system, in line with the presence of a functional Sec dependent secretion system in phytoplasma; and to reveal their potential role in manipulating host metabolism;
  • to evaluate the expression of potential phytoplasma effector candidates in different BN strains in different hosts;to evaluate the effect of BNp and its effectors on plant phenotype and gene expression;
  • to develop functional approaches for developing strategies for resistance breeding based on a modulation of carbohydrate and cytokinin hormone status in transgenic plants;
  • to construct an improved model of the phytoplasma/host system, which will assist in biological interpretation of the results.