Identification of six differentially accumulated proteins of Zea mays seedlings (DKB240 variety) inoculated with Azospirillum brasilense strain FP2

• Two-dimensional electrophoresis analysis of maize roots inoculated with A. brasilense.
• Six differentially expressed proteins were identified in inoculated roots.
• Two down-regulated: Zea mays annexin2 and hypothetical protein LOC100275372.
• Two up-regulated: A. brasilense ATPase beta chain and major outer membrane protein OmaA.
• Two spots exclusively expressed: A. brasilense malate dehydrogenase.

The plant growth promoting bacteria (PGPB) Azospirillum brasilense has been known to exert beneficial influence on inoculated plants, such as maize and wheat. The successful PGPB-plant association depends on plant and PGPB genotypes and it was not fully understood. In this study we have employed two-dimensional gel electrophoresis and mass spectrometry to analyze the changes in protein profile of maize roots in response to A. brasilense strain FP2 ten days after inoculation and 87 differently expressed protein spots were revealed. We report the identification of six of these proteins in detail: Two down-regulated proteins in inoculated roots, Zea mays annexin2 (2-fold) and Z. mays hypothetical protein LOC100275372 (4-fold), that is 60% similar to an Arabidopsis thaliana hydroxyproline-rich glycoprotein-like protein; two up-regulated proteins in inoculated roots, A. brasilense F-type H+-transporting ATPase beta chain (3-fold) and A. brasilense major outer membrane protein OmaA precursor (14-fold). Two spots exclusively expressed in inoculated roots were identified as A. brasilense malate dehydrogenase.