Characterization of beneficial bacteria isolated from grapevine leaves

Bacterial endophytes are plant-associated bacteria that affect the plant life cycles in different manners such as nitrogen fixation or the biocontrol of plant pathogens (Lugtemberg and Kamilova 2009). A basic point for the success of sustainable management of plant diseases based on biocontrol agents is the study of endophytic bacterial community associated with plants. Recently endophytic bacteria associated with healthy, grapevine yellows (GY)-diseased and recovered grapevine plants have been described suggesting some putative biocontrol agents (Bulgari et al., 2009; 2011). In the present work, endophytic bacteria isolated from healthy diseased and recovered grapevine plants were characterized for five beneficial traits related to mineral nutrition (phosphate solubilization, siderophores), development (indolacetic acid-IAA synthesis), stress relief (1-amino-cyclopropane-1-carboxylate deaminase and catalase activity), disease control (chitinase activity, siderophores). In detail, five bacterial isolates showed the ability to solubilize phosphate, react to stress and to synthesize IAA. In addition, some of these strains are able to produce siderophores. Furthermore, the distribution of three bacterial genera was analyzed in healthy, GY-diseased and recovered grapevine plants sampled from June to October. At the genus level we found a different bacterial distribution related to the season and to sanitary status. In conclusion, we have characterized and detected beneficial bacterial strains from grapevine leaves which have the potential to enhance plant growth and suppress diseases.