Bacillus licheniformis increases growth and induces synthesis of defense-related terpenes in grape plants

SALOMON M.V.; GIL M.; INZIRILLO G.; BOTTINI R.; PICCOLI P.

Tucumán

Congreso; XVII Congreso Argentino de Microbiología General; 2011

Sociedad Argentina de Microbiología General

Plant growth promoting bacteria (PGPR) are bacteria that improve growth and yield in plants, but also help to protect the host against several abiotic and biotic stresses. The mechanisms by which bacteria produce such a benefit for the plant include production of phytohormones, which act as chemical signals that may induce metabolic changes in the host. We have previously isolated and characterized by 16S rRNA gene sequences analysis several bacterial strains from roots and adjacent soil of grape plants, among them Bacillus licheniformis. We also found that some of the isolates produce abscisic acid (ABA), indole acetic acid (IAA) and gibberellins (GAs) in chemically-defined medium. The aim of this study was to evaluate growth differences and defense-related terpenes in grape plants inoculated or not with this indigenous bacterium. Roots of 15 days in vitro grown grape plants were inoculated with 100 ul of B. licheniformis culture (2x107 CFUml-1). After 45 days the plants were removed, growth parameters were measured, and the leaves were extracted for ABA, GAs, IAA and terpene profile determination by capillary gas chromatography coupled with electron impact mass spectrometry (GC-EIMS). Inoculation with B. licheniformis increased stem and root length, and enhanced the defense-related terpenes; e.g. the monoterpenes pinene, terpinolene and cineole, as well as the sesquiterpenes farnesol, trans-á bergamotene, á-farnesene and nerolidol. In leaves of control plants only pinene and nerolidol were detected but in trace amounts. The results suggest that B. licheniformis promotes the plant growth by increasing ABA, IAA and GA levels and induces the synthesis of defense-related compounds against potential pathogens.