Azospirillum

Abstract

Genus Azospirillum is one of the plant growth promoting rhizobacteria (PGPR) best studied and most used for the agricultural production. Although more than 20 species have been described within the genus at present (DSMZ 2018, Bashan and De-Bashan, 2010, Hungary et al, 2010, 2011, Fukami et al., 2016, Peret et al., 2016), A. brasilense and A. lipoferum are the best characterized both biochemically and genetically (Baldani and Baldani 2005, Fibach-Paldi et al., 2012) and the most widely used in commercial inoculants.This microorganism colonize more than one hundred plant species and exist abundant information about the improve in growth, development and production in field conditions (Bashan and de-Bashan, 2010; Cassan and Diaz-Zorita, 2016). Although early studies regarding the effects of Azospirillum to induce plant growth were mainly associated with the capacity to fix N2, today it is known that the bacterium has different additional mechanisms that contribute to greater growth and crop yield. Bashan and De-Bashan (2010) proposed the ?theory of multiple mechanisms? in which the bacterium in its interaction with the plant and the environment deploys a series of mechanisms in a simultaneous or consecutive manner, in which general and/or specific patterns of each particular interaction are generated. Among the other addicionaly mechanisms that contribute to the promoting plant growth, the phosphate solubilization, phytohormone and/or siderophore production (Puente et al., 2004), phytopathogens control (Bashan and de-Bashan, 2010) and protection against abiotic stress like drought, salinity or toxic compounds (Creus et al., 1997), have been characterized.