Azospirillum sp. promotes root hair development in tomato plants through a mechanism that involves ethylene

RIBAUDO CM; KRUMPHOLZ EM; CASSÁN FD; BOTTINI R; CANTORE ML; CURÁ JA

JOURNAL OF PLANT GROWTH REGULATION

Springer

Año: 2006 vol. 25 p. 175 - 185

0721-7595

Tomato seeds were inoculated with the plant growth promoting rhizobacteria Azospirillum brasilense FT326 and changes in parameters associated with plant growth were evaluated 15 days after inoculation. Azospirilla were localized on roots and within xylematic tissue. An increase in shoot and root fresh weight, main root hair length and root surface indicated that inoculation with A. brasilense FT 326 resulted in plant growth improvement. The levels of IAA and ethylene, two of the phytohormones related to plant growth, were higher in inoculated plants. Exogenously supplied 24 ethylene mimicked the effect of inoculation and the addition of an inhibitor of its synthesis or of its physiological activity completely blocked A. brasilense growth promotion. Based on our results we propose that the process of growth promotion triggered by A. brasilense inoculation involves a signaling pathway that has ethylene as a central, positive regulator.