INVESTIGADORES
SANNAZZARO Analia Ines
congresos y reuniones científicas
Título:
Pantoea eucalypti M91: Here, there and everywhere
Autor/es:
CASTAGNO, LUIS NAZARENO; SANNAZZARO, ANALIA INÉS; CUMPA VELÁZQUEZ, LIZ; PIECKENSTAIN, FERNANDO L; ESTRELLA, MARIA JULIA
Lugar:
La Falda
Reunión:
Taller; II Taller Latinoamericano sobre Rizobacterias Promotoras del Desarrollo Vegetal; 2014
Resumen:
Introduction Pantoea eucalypti M91 is a P-solubilizing bacteria (PSB), isolated from soils of the Salado River Basin. A field experiment showed that accumulated biomass production of Lotus tenuis plants was increased by inoculation with P. eucalypti M91 in a similar degree to triple superphosphate (TSP) and phosphate rock fertilization. Moreover, the combination of M91 inoculation and TSP fertilization increased P accumulation in shoot tissues and also led to a significant increase in shoot-N concentration. In view of these results we consider that potential of P. eucalypti M91 as a biofertilizer is worth to be explored. Thus, in a first experimental approach, we analyzed the ability of P. eucalypti M91 to colonize plant tissues and survive to environmental conditions, in both in vitro and field assays. Materials and Methods In vitro experiment: For these assays we used P. eucalypti M91 expressing RFP and gentamicin resistance, which was generated by four-parental mating conjugation. Suspensions serially diluted in 10-fold increments obtained from the bulk soil, rhizosphere and superficially disinfected plant tissues were cultured on TY plates containing gentamicin (10 µg/ml) in order to quantify M91´s viable bacterial number in these different locations. Field experiment: In order to confirm the endophytic colonization at field conditions, endophytic PSB bacteria were isolated from roots and shoots of second harvest´s plants (23 weeks). BOX-PCR patterns of the isolated strains were obtained and compared with those of P. eucalypti M91. Results The in vitro experiment was used to evaluate the survival, dissemination and localization of P. eucalypti M91 after inoculation of L. tenuis seedlings. Viable bacterial number was constant through time both in the soil bulk and the rizosphere, being more abundant in the rhizospheric soil. M91 was also found endophytically colonizing shoot and root tissues of L. tenuis plants. It is worth to be noted that a surprisingly high number of bacterial counts were obtained from both organs only a few days after inoculation. Furthermore, the endophytic behaviour of P. eucalypti M91 was confirmed to occur in an inoculation experiment under field conditions, where the inoculant was detected in shoot tissue after L. tenuis second harvest. Interestingly, a higher number of other endophytic isolates was found in shoots and roots of M91-inoculated plants, as compared to non-inoculated controls. Moreover, no endophytic bacteria were recovered from leaves of non-inoculated plants. Conclusions A desirable condition for a good quality biofertilizer is the long-term survival of the involved microorganisms. P. eucalypti M91 is an interesting candidate to be used as a biofertilizer, not only because of its P-solubilizing capability, but also given the prevalence of this strain in soil, rhizosphere and the different plant organs, which may constitute an advantage over competitive indigenous populations. The presence of a higher number of other endophytic PSB in P. eucalypti M91-inoculated plants, as compared to non-inoculated ones, suggests that inoculation with M91 strain may somehow enable plant colonization by other beneficial microorganisms.