Diversity of bacterial endophytes in 3 and 15 year-old grapevines of Vitis vinifera cv. Corvina and their potential for plant growth promotion and phytopathogen control

tThis study represents the first investigation on ecology of endophytic bacteria isolated from 3 and 15 year-old vine stems of Vitis vinifera cv. Corvina. The analysis was performed by means of culture-dependenttechniques. The obtained results showed that new grapevine endophytic genera are being discovered.Moreover, Bacilli and Actinobacteria are frequently isolated from 3 year-old plants, whereas Alpha- andGamma- Proteobacteria classes are more prevalent in the 15 year-old plants. Shannon–Wiener (H) indexand analysis of rarefaction curves revealed greater genus richness in young grapevine plants. Further-more, results evidenced an increase of genotypic group number within specific genera (e.g., Rhizobiumand Pantoea).Among isolated strains from 3 and 15 year-old stems, respectively, 34 and 39% produce siderophores;22 and 15% secrete ammonia; 22 and 21% produce indole-3-acetic acid; 8.7 and 41% solubilize phosphate.Besides, two strains isolated from 15 year-old grapevines showed 1-aminocyclopropane-1-carboxylatedeaminase activity. Antifungal activity analysis evidenced that two Bacillus strains possess growth antag-onistic effect toward all the tested fungal strains. Therefore, the present study extends our knowledge ofthe diversity of the endophytic bacteria by providing new insights into the complexity of the grapevinemicrobiome.