Quantitative real time PCR was used to follow the seasonal changes of the Flavescence dorée phytoplasma (FDp) titre in different grapevine tissues. FDp presence was determined in flowers and tendrils with a high concentration in berries. In tissues with symptoms a trend of an increasing FDp titre throughout the growing season was recorded. Early detection of FDp in symptomless tissues was possible and positively correlated with high infection pressure. A gene expression analysis of fourteen selected genes during the growing season revealed that statistically significant differences between healthy and FDp infected plants occur in August at the time of symptoms. At this time the gene expression was similar to previous studies on the grapevine - Bois noir phytoplasma (BNp) interaction. From gene expression profiles we could distinguish the health status of plants sampled in summer. In August we determined higher amounts of sugars, mainly sucrose and starch, in BNp and FDp infected plants compared to healthy plants. Additionaly, we determined higher activity of the sucrose synthase (SUSY) enzyme but unchanged activity of the ADP-glucose pyrophosphorylase (AGPase) and neutral invertase (nINV) enzymes in FDp infected plants. Using the GC-MS technique we determined that both phytoplasmas (BNp and FDp) cause a different metabolic fingerprint, which can be the consequence of a different grapevine cultivar used in the interaction study and/or a different phytoplasma type. The PCA analysis based on all metabolites showed a separation of healthy and phytoplasma infected samples. The main metabolites responsible for the health status separation are however different in both interactions. Both phytoplasmas induce higher levels of hexose 6-phosphates, which as the starting molecule of glycolysis could be the main energy source for phhytoplasmas. Phytoplasma pathogenicity is presumably due to a decreased sucrose loading in phloem, which slows down sugar transport to sink tissues, this leading to an insufficient sugar accumulation in berries and harvest loss.
F.02 Acquisition of new scientific knowledge
COBISS.SI-ID: 818551Scaphoideus titanus is a leafhopper, the natural vector of the phytoplasma that causes “flavescence dorée” (FD), the most important causer of grapevine yellow diseases. The most important measure for successfull prevention of FD in vineyards is timely management of Scaphoideus titanus. For this purpose we began to develop a phenology model that will contribute to predict timely application of insecticides to control larva and adult leafhoppers. The most important data which are necessary to include into phenology model are: post-dormancy egg development, patterns of egg hatching, duration of developmental stages of larvae and nymphs and development of adult leafhoppers. In the following contribution present the bionomics data of American leafhopper, which were obtained in 2012, under controlled conditions, growing chamber, as well as outdoors in vineyards. The data will contribute to development of phenology model for predict the management of American leafhopper.
F.18 Transfer of new know-how to direct users (seminars, fora, conferences)
COBISS.SI-ID: 615820In grapevine, phytoplasmas cause grapevine yellows (GY) diseases, which were identified in the majority of grapevine growing countries worldwide. Several molecularly distinct phytoplasma groups which cause the GY were identified; however, a phytoplasma from the stolbur group/16SrXII-A, associated with the GY disease Bois noir (referred herein to as BNp), is very common. In our previous study we have shown a comparison of the global transcriptome profile of healthy and BNp infected grapevine (Vitis vinifera) cv. Chardonnay. In the two-year-long field experiment a set of 17 selected genes from several differentially expressed pathways was analyzed and confirmed to be suitable for a reliable classification of infected plants and for the characterization of susceptibility features in the field conditions. Based on those results, in the following study this set was increased to 22 genes, and the experiment was prolonged to five years. Classification trees were used in order to reveal possible marker genes that may be used in new diagnostic assays.
B.04 Guest lecture
COBISS.SI-ID: 2872143Remote sensing analysis of high resolution satellite images as a support to targeted monitoring of Grapevine Flavescence dorée phytoplasma was presented.
F.18 Transfer of new know-how to direct users (seminars, fora, conferences)
COBISS.SI-ID: 3805544