IBBM   21076
INSTITUTO DE BIOTECNOLOGIA Y BIOLOGIA MOLECULAR
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
AN INOCULANT BRADYRHIZOBIUM STRAIN WITH INCREASED MOTILITY IMPROVES YIELD OF SOYBEAN CROPS
Autor/es:
COLLA, DELFINA; COVELLI, JULIETA M.; LODEIRO, ANÍBAL R.; BRIGNOLI, DAMIÁN; ALTHABEGOITI, MARÍA JULIA; PÉREZ-GIMÉNEZ, JULIETA; ITURRALDE, ESTEBAN TOMÁS; PERTICARI, ALEJANDRO
Lugar:
Online
Reunión:
Congreso; V Congreso Argentino de Microbiología Agrícola y Ambiental (V CAMAyA); 2021
Institución organizadora:
División de Microbiología Agrícola y Ambiental (DiMAyA)
Resumen:
Soybean production is very important in Argentina, where more than 20 million hectares are sowedannually with this crop. Since soybean plants possess a very high N-demand, it is crucial that thisagricultural activity is developed in a sustainable way because otherwise, this crop could deplete Nnutritionfrom the soils, leading to erosion, compaction, and flooding. Soybean roots are nodulatedby Bradyrhizobium spp., which may fix atmospheric N2 in symbiosis with the plant, thus contributingto keep the N-status of the soil. For this reason and due to their low cost, Bradyrhizobium spp. arewidely used in inoculants for soybean crops. However, the efficiency of inoculants is low due to thecompetition exerted by bradyrhizobia resident in the soil. Among factors that affect the competitionfor nodulation is the self-propelled motility of the rhizobia.Previously, we developed an artificial selection method to obtain bradyrhizobial strains with highermotility. B. japonicum E109 is the strain recommend by INTA for inoculants production. Therefore,we used E109 to increase its motility, and hereby we obtained the derived B. japonicum E109 m+strain. This strain possesses 50% more motility than its parental strain in semisolid agar medium,and has the same growth kinetics as the wild type, ruling out the possibility that the increasedspreading of E109 m+ in semisolid agar be due to faster growth.B. diazoefficiens have two flagella systems, one subpolar and another lateral, characterized byflagellins of different molecular weights. The subpolar flagellum has constitutive expression and thelateral is inducible with L-arabinose as carbon source, but not with D-mannitol as carbon source.However, E109 m+ expressed both flagella with D-mannitol, as observed with SDS-PAGE of purifiedflagellins, in agreement with previous results obtained with B. diazoefficiens USDA 110.B. japonicum E109 m+ nodulated soybean and after that, bacteria recovered from nodulesmaintained the higher motility phenotype. Field trials were performed to estimate yield when thesoybean plots were inoculated with E109 m+ or the E109 parental strain. Experiments were carriedout in San Antonio de Areco, Province of Buenos Aires, in a soil with a competitive residentBradyrhizobium spp. population, employing a randomized complete block design that includeduninoculated controls. Grain yields were compared by ANOVA, which indicated that inoculation withE109 m+ led to significantly higher yield than inoculation with E109 wild type.Our results suggested that inoculation of soybean with improved motility strains could increasesoybean yield by enhancing competition for nodulation in a sustainable way.