Stable symbiotic nitrogen fixation under water-deficit field conditions by a stress-tolerant alfalfa microsymbiont and its complete genome sequence.

JOZEFKOWICZ C; BRAMBILLA S; FRARE R; STRITZLER M; PICCINETTI C; PUENTE M; BERINI C; REYES PÉREZ P; SOTO G; AYUB N

JOURNAL OF BIOTECHNOLOGY

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2017

0168-1656

We characterized the stress-tolerant alfalfa microsymbiont Sinorhizobium meliloti B401. B401-treated plants showed high nitrogen fixation rates under humid and semiarid environments. The production of glycine betaine in isolated bacteroids positively correlated with low precipitation levels, suggesting that this compound acts as a critical osmoprotectant under field conditions. Genome analysis showed that strain B401 contains chromosomal genes related to the biosynthesis and uptake of glycine betaine and its precursors, and an additional gene cluster situated within a non-chromosomal autonomous replicon megaplasmid A, putatively involved in glycine betaine and choline uptake, and probably acquired by horizontal transfer. Such genomic information will offer substantial insight into the environmental physiology of this biotechnologically valuable nitrogen-fixing bacterium.