Characterization and screening of plant probiotic traits of bacteria isolated from rice seeds cultivated in Argentina

RUIZ D; AGARAS B; DE WERRA, P; WALL LG; VALVERDE C

JOURNAL MICROBIOLOGY

MICROBIOLOGICAL SOCIETY KOREA

Lugar: Korea ; Año: 2011

1225-8873

Many seeds carry endophytes, which ensure good chances of seedling colonization. In this study, we have studied the seed-borne bacterial flora of rice varieties cultivated in the northeast of Argentina. Surface sterilized husked seeds of rice cultivars CT6919, El Paso 144, CAMBA and IRGA 417 contained an average of 5  106 CFU/g of mesophylic and copiotrophic bacteria. Microbiological, physiological, and molecular characterization of a set of 39 fast growing isolates from CT6919 seeds revealed an important diversity of seed-borne mesophyles and potential plant probiotic activities including diazotrophy and antagonism of fungal pathogens. In fact, the seed-borne bacterial flora protected rice seedlings against Curvularia sp. infection. The root colonization pattern of two Pantoea isolates from seeds was studied by fluorescence microscopy of inoculated axenic rice seedlings. Both isolates strongly colonized the site of emergence of lateral roots, and lenticels, which may represent entry sites for endophytic spreading. These findings suggest that rice plants allow grain colonization by bacterial species that may act as natural biofertilizers and bioprotectives early from seed germination.