Major cereal crops benefit from biological nitrogen fixation when inoculated with the nitrogen-fixing bacterium Pseudomonas protegens Pf-5 X940.

ANA ROMINA FOX; GABRIELA SOTO; CLAUDIO VALVERDE; DANIELA RUSSO; ANTONIO LAGARES; ANGELES ZORREGUIETA; KARINA ALLEVA; CECILIA PASCUAN; ROMINA FRARE; JESÚS MERCADO BLANCO; RAY DIXON; NICOLAS AYUB

ENVIRONMENTAL MICROBIOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2016

1462-2912

A main goal of biological nitrogen fixation (BNF) research has been to expand the nitrogen fixingability to major cereal crops. In this work, we demonstrate the use of the efficientnitrogen-fixing rhizobacterium Pseudomonas protegens Pf-5 X940 as a chassis to engineerthe transfer of nitrogen fixed by BNF to maize and wheat under non-gnotobiotic conditions.Inoculation of maize and wheat with Pf-5 X940 largely improved nitrogen content andbiomass accumulation in both vegetative and reproductive tissues, and this beneficial effectwas positively associated with high nitrogen fixation rates in roots. 15N isotope dilutionanalysis showed that maize and wheat plants obtained substantial amounts of fixed nitrogenfrom the atmosphere. Pf-5 X940-GFP-tagged cells were always reisolated from the maize andwheat root surface but never from the inner root tissues. Confocal laser scanning microscopyconfirmed root surface colonization of Pf-5 X940-GFP in wheat plants, and microcolonieswere mostly visualized at the junctions between epidermal root cells. Genetic analysis usingbiofilm formation-related Pseudomonas mutants confirmed the relevance of bacterial rootadhesion in the increase in nitrogen content, biomass accumulation and nitrogen fixation ratesin wheat roots. To our knowledge, this is the first report of robust BNF in major cereal crops.