Plant and Cell Physiology, 2001, Vol. 42, No. 7 763-767
© 2001 Oxford University Press
Azospirillum spp. metabolize [17,17-2H2]gibberellin A20 to [17,17-2H2]gibberellin A1 in vivo in dy rice mutant seedlings
1 Laboratorio de Fisiología Vegetal, Departamento de Ciencias Naturales, Universidad Nacional de Río Cuarto, Campus Universitario, 5800 Río Cuarto, Argentina
Azospirillum spp. are endophytic bacteria with beneficial effects on cereals — effects partially attributed to gibberellin production by the microorganisms. Azospirillum lipoferum and Azospirillum brasilense inoculated to rice dy mutant reversed dwarfism in seedlings incubated with [17,17-2H2]GA20 with formation of [17,17-2H2]GA1, showing the in vivo capacity to perform the 3ß-hydroxylation. When Prohexadione-Ca, an inhibitor of late steps in gibberellin biosynthesis, was added to the culture medium, no complementation was observed and no [17,17-2H2]GA1 was produced. The latter suggests that the bacterial operating enzyme may be a 2-oxoglutarate-dependent dioxygenase, similar to those of plants.
2 Present address: Estación Experimental Agropecuaria San Pedro, Instituto Nacional de Tecnología Agropecuaria, 3290 San Pedro, Argentina.
3 Corresponding author: E-mail, rbottini@exa.unrc.edu.ar; Fax, +54-358-4676230.