|1461-1||METABOLISM OF INDOLE-3-ACETIC ACID IN Burkholderia xenovorans LB400 AND ITS EFFECT ON Vitis vinifera GROWTH|
|Autores:||Paulina Vega-celedón (UTFSM - Universidad Técnica Federico Santa María) ; Hayron Canchignia (UTFSM - Universidad Técnica Federico Santa María) ; Myriam González (UTFSM - Universidad Técnica Federico Santa María) ; Michael Seeger (UTFSM - Universidad Técnica Federico Santa María) |
Plant growth-promoting rhizobacteria (PGPR) are able to stimulate the plant growth by different mechanisms including the production of phytohormones. Indole-3-acetic acid (IAA) is the main auxin in plants, controlling diverse important physiological processes including cell enlargement and division, tissue differentiation, and responses to light and gravity. Burkholderia xenovorans LB400 is a nonpathogenic soil bacterium well known for its metabolism of aromatic compounds. The objective of this study was to analyze the metabolism of IAA in B. xenovorans LB400 and its effect on the Vitis vinifera growth. The synthesis and degradation of IAA and their possible metabolic routes were analyzed by HPLC quantification and RT-PCR assays. Burkholderia xenovorans LB400 is capable to synthesize IAA in minimal and rich media in presence of tryptophan and an additional carbon source. Under both growth conditions, B. xenovorans LB400 expressed the ipdC gene that encodes the indole-3-pyruvate decarboxylase, suggesting the use of the indol-3-pyruvate (IPA) pathway for the IAA synthesis. Resting cells of strain LB400 were also able to degrade this phytohormone. In presence of IAA, strain LB400 transcribed the iacC gene that encodes a dioxygenase involved in the catabolism of IAA. The growth-promoting activity of B. xenovorans LB400 on the plant Vitis vinifera cvs. Thompson Seedless was evaluated. LB400 cells (109 CFU mL-1) were applied on Vitis vinifera cuttings in agar (3 g L-1) at 25 °C. The presence of bacterial cells increased significantly the number of plant roots after an incubation of thirty days (p<0,05). In conclusion, this study showed that Burkholderia xenovorans strain LB400 is capable to degrade and synthesize the phytohormone IAA and also promotes the growth of Vitis vinifera.
Palavras-chave: Indole-3-acetic acid, Burkholderia xenovorans LB400, Vitis vinifera, Metabolism