Bacteria isolated from roots and rhizosphere of Vitis vinifera retarded water losses via production of abscisic acid and induced synthesis of defense-related terpenes in in vitro cultured grapevine

SALOMON MV; BOTTINI R; COHEN A; MORENO D; PICCOLI P

Shanghai

Conferencia; the 21st Conference of the International Plant Growth Substances Association (IPGSA); 2013

International plant growth substances association

Eleven bacterial strains were isolated at different soil depths from roots and rizhosphere of grapevines from a commercial vineyard. By 16S rRNA gene sequencing 9 strains were identified, among them Bacillus licheniformis RtM10 and Pseudomonas fluorescens RtM10 were selected according to their characteristics as plant growth promoting rizhobacteria (PGPR). Both produced abscisic acid (ABA), indol-3-acetic acid (IAA) and the gibberellins A1 and A3 in chemically-defined medium. They also colonized roots of in vitro-grown Vitis vinifera cv. Malbec plants. As result of bacterization ABA levels in 45 days-old in vitro plants were increased 76-fold by B. licheniformis and 40-fold by P. fluorescens as compared to controls. Both bacteria diminished plants water loss rate in correlation with increments of ABA. Twenty and 30 days post bacterization the plants incremented terpenes. The monoterpenes α-pinene, terpinolene, 4-carene, limonene, eucalyptol and lilac aldehyde A, and the sesquiterpenes α-bergamotene, α-farnesene, nerolidol and farnesol were assessed by gas chromatography-electron impact mass spectrometry analysis. α-pinene and nerolidol were the most abundant (µg per g of tissue in plants bacterized with P. fluorescens). Only α-pinene, eucalyptol and farnesol were identified at low concentration in non-bacterized plants treated with ABA, while no terpenes were detected in controls. The results obtained along with others from literature suggest that B. licheniformis and P. fluorescens act as stress alleviators by inducing ABA synthesis so diminishing water losses. These bacteria also elicit synthesis of compounds of plant defense via an ABA independent mechanism.Conclusion. B. licheniformis and P. fluorescens operate as PGPR in the interaction with the grapevines at least by two different mechanisms, one by producing and inducing synthesis of ABA that alleviates plants from drought conditions and, by inducing synthesis of terpenes as defense compounds, other via an ABA independent mechanism. It is also clear that P. fluorescens induce most strongly the synthesis of terpenes since the plants bacterized with this bacterium showed significantly high