COMPARATIVE TRANSCRIPTOME ANALYSIS OF FOUR OLIVE CULTIVARS IN RESPONSE TO INFECTION BY XYLELLA FASTIDIOSA

The recent outbreak of Olive Quick Decline Syndrome (OQDS) caused by the bacterium Xylella fastidiosa subsp. pauca is radically changing agriculture on the Salento peninsula in the Apulia Region, in Southern Italy. Despite great efforts, it has not yet been possible to bring the disease under control, so a better knowledge of the mechanisms of disease ethiology is needed. The main focus of this project was a comparative transcriptome analysis of four olive cultivars known for their different susceptibilityto Xylella: Leccino and Donna Francesca as tolerant, and Oliva Rossa and Cellina as susceptible. Olive samples were grown in certified screenhouseat DiSSPA- University of Bari Aldo Moro, and for each cultivar, three replicates from healthy plants and three replicates infected with X.f. were analysed. The total RNA was extracted from leaf and pidicel tissue using a commercial kit, the RNA-seq libraries were synthesized and sequenced on Illumina platform Novaseq 6000. The analysis revealed genes with differential expression in the two resistant and the two susceptible varieties. Data analysis revealed a complex pattern of gene expression with more than 800 differentially expressed genes (DEGs) including a number of defense-related genes.