Influence of arbuscular Mycorrhizae and Rhizobium on free polyamines and proline levels in water-stressed alfalfa

The objective of this research was to study the effect of drought on polyam ine and proline levels in alfalfa (Medicago sativa L. cv. Aragon) plants in oculated with a mycorrhizal fungus and/or Rhizobium compared with non-inocu lated ones. The four treatments were: a) plants inoculated with Glomus fasc iculatum (Taxter sensu Gerd.) Gerdemann and Trappe and Rhizobium meliloti 1 02 F51 strain (MR), b) plants inoculated with Rhizobium only (R), c) plants inoculated with Glomus only (M), and d) non-inoculated plants (N). Plants were drought stressed during two cycles of moisture stress and recovery. Al though proline concentrations increased and free polyamine (spermidine and spermine) contents decreased in leaves and roots of alfalfa under water str ess, symbiotic R, M and MR plants maintained higher free polyamine concentr ations than non-symbiotic N ones. Results suggest that symbiotic alfalfa pl ants are better adapted than non-symbiotic ones to cope with water deficit.