Interacciones pre-simbióticas y simbióticas entre Glomus intraradices y dos especies de Paenibacillus aisladas de propágulos MA. Ensayos in vitro e in vivo con soja (AG043RG) como planta hospedante

FERNÁNDEZ BIDONDO LAURA; VANESA SILVANI; ROXANA COLOMBO; PERGOLA MARIANA; JOSEFINA BOMPADRE; ALICIA GODEAS

Buenos Aires

Jornada; 1as. Jornada Temática del INBA: “La investigación científico-técnica en soja“; 2011

inba

Two indole-producing Paenibacillus, known to be associated with propagules of arbuscular mycorrhizal (AM) fungi, were examined for their mycorrhization helper bacteria activity at pre-symbiotic and symbiotic stages of the AM association. Effects were tested under in vitro and in vivo conditions using an axenically propagated strain of Glomus intraradices and soybean as host plant. Spore germination and re-growth of intraradical mycelium were not affected by inoculation with Paenibacillus strains in spite of the variation of indole production measured in the bacterial supernatants. However, a significant promotion in pre-symbiotic mycelium development occurred after inoculation of both bacteria under in vitro conditions. P. rhizosphaerae TGX5E significantly increased the extraradical mycelium network, sporulation, and root colonization in the in vitro symbiotic association. These results were also observed in the rhizosphere of soybean plants grown under greenhouse conditions, when P. rhizosphaerae was co-inoculated with G. intraradices. However, soybean dry biomass production was not associated with the increased development and infectivity values of G. intraradices. P. favisporus strain TG1R2 caused suppression of the parameters evaluated for G. intraradices during in vitro symbiotic stages, but not under in vivo conditions. In addition, dual inoculation had a promoting effect on soybean biomass production. Species of Paenibacillus associated with AM structures, may have a promoting effect on short term pre-symbiotic mycelium, and little impact on AM propagule germination. These findings could explain the associations found between some bacterial strains and AM fungus propagules.