Bacterial isolates from strawberry plants (Fragaria x ananassa Duch.): evaluation of important traits for biological control and plant growth promotion

HIRSCH, MAILÉN; BURGES, PABLO L.; VILLARREAL, NATALIA M.; MARINA, MARÍA

Los Cocos

Congreso; XVII Congreso Argentino de Microbiología Genereal; 2022

Sociedad Argentina de Microbiología General

Many microorganisms coexist with plants and interact beneficially with them. They may confer plant protection against pathogens by different mechanisms of action and even stimulate plant growth and health. Biological control consists of the use of such beneficial organisms for the management of phytopathogens and constitutes an alternative to the use of agrochemicals. Bacteria, yeasts, and other fungi have been extensively studied and evaluated as biological control agents (BCA) and their application in agriculture. The present study focuses on beneficial bacteria, both epiphytic and endophytic, isolated from strawberry plants. Identifying possible modes of action of a strain is an important point in the selection of potential BCAs and plant growth promoters (or PGPB for plant growth-promoting bacteria). Therefore, we evaluated different characteristics related to thesebiological functions in 11 bacteria (seven epiphytes and four endophytes) isolated from leaves and strawberry fruits. We characterized lytic enzyme synthesis (cellulase, protease, and lipase), biofilm formation, and siderophores production. In addition, we measured the root length, the number of lateral roots, and fresh weight in Arabidopsis thaliana seedlings after inoculation with each bacterium. It is important to note that these bacteria inhibit the in vitro growth of Botrytis cinerea (previously evaluated). Added to this characteristic, all showed a capacity to form biofilm and synthesize at least one lytic enzyme. Also, some epiphytes were able to produce siderophores. These properties are relevant not only for phytopathogen’s antagonism but also for the colonization and establishment ofthe bacteria in the plant. On the other hand, some bacterial strains produced significant changes after inoculation into A. thaliana seedlings. These differences were observed in the number of lateral roots and fresh weight, but not in root length, comparing with control seedlings inoculated with 10 mM MgCl2. Considering all results, three epiphytes isolated from leaves (HII1, HII4, and HIII11) showed the most promising results. Through 16S rRNA gene sequencing and bioinformatic analysis, we identified that the isolates belong to the genus Bacillus. These approaches are necessary for the first step to studying possible BCAs and PGPB and provide us with valuable information to continue working on an eco-friendly strategy for disease control in strawberry plants.