title: Nitrate inhibition of nodulation can be overcome by the ethylene inhibitor aminoethoxyvinylglycine.
abstract: Previously, we reported (a) a positive correlation between the nitrate concentrations in growth medium and ethylene evolved from uninoculated and inoculated alfalfa (Medicago sativa) roots and (b) a negative correlation between ethylene evolution and nodulation. Here, we report that the inhibitory effect of NO(3) (-) on nodulation of alfalfa can be eliminated by the ethylene inhibitor aminoethoxyvinylglycine (AVG). This effect was probably related to the strong inhibition (90%) of ethylene biosynthesis caused by AVG in these inoculated and NO(3) (-)-treated roots. These results support our hypothesis that the inhibitory effect of NO(3) (-) is mediated through the phytohormone ethylene. A possible role of endogenous ethylene in the autoregulation of nodulation also is discussed. AVG at 10 micromolar significantly (P < 0.05) increased total nitrogenase activity (acetylene reduction) in 2.5 and 5 millimolar NO(3) (-)-fed plants probably as a result of the very high stimulation of nodulation.
authors: Grupo de Investigación "Fijación de Nitrógeno," Universidad de Granada, Departamento de Biología Vegetal, E-18071 Granada, Spain.
authors: F
authors: F
authors: Ligero
authors: J M
authors: JM
authors: Caba
authors: C
authors: C
authors: Lluch
authors: J
authors: J
authors: Olivares