Seasonal dynamics of kiwifruit microbiome: A case study in a KVDS-affected orchard.

Over the past decade, Italian kiwifruit orchards and overall production have faced a significant threat from Kiwifruit Vine Decline Syndrome (KVDS). Despite the insights gained from metagenomics studies into the microbial communities associated with the disease, unanswered questions still remain. In this study, the evolution of bacterial, fungal, and oomycetes communities in soil and root endosphere at three different time points during the vegetative season was investigated for the first time in a KVDS-affected orchard in the Lazio Region. The fungal and oomycetes genera previously associated with the syndrome, including Fusarium, Ilyonectria, Thelonectria, Phytophthora, Pythium and Globisporangium, were identified in both groups. In contrast, the characterization of bacterial communities revealed the first instance of the presence of the genus Ralstonia in soil and root samples. The microbiome composition shifts between KVDS-affected and asymptomatic plants were significant as evidenced by the results, particularly after a temperature increase. This temperature change coincided with the onset of severe disease symptoms and may indicate a key role in the progression of KVDS.