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Quantitative Proteomic Analysis of the Interaction Between the Endophytic Plant-Growth-Promoting Bacterium Gluconacetobacter diazotrophicus and Sugarcane

May 2011 , Volume 24 , Number  5
Pages  562 - 576

Letícia M. S. Lery,1 Adriana S. Hemerly,2 Eduardo M. Nogueira,2,3 Wanda M. A. von Krüger,1 and Paulo M. Bisch1

1Unidade Multidisciplinar de Genômica, Instituto de Biofísica Carlos Chagas Filho da Universidade Federal do Rio de Janeiro, Brazil; 2Laboratório de Biologia Molecular de Plantas, Instituto de Bioquímica Médica da Universidade Federal do Rio de Janeiro, Brazil; 3Departamento de Genética e Biologia Molecular, Universidade Federal do Estado do Rio de Janeiro, Brazil

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Accepted 21 December 2010.

Gluconacetobacter diazotrophicus is a plant-growth-promoting bacterium that colonizes sugarcane. In order to investigate molecular aspects of the G. diazotrophicus–sugarcane interaction, we performed a quantitative mass spectrometry-based proteomic analysis by 15N metabolic labeling of bacteria, root samples, and co-cultures. Overall, more than 400 proteins were analyzed and 78 were differentially expressed between the plant–bacterium interaction model and control cultures. A comparative analysis of the G. diazotrophicus in interaction with two distinct genotypes of sugarcane, SP70-1143 and Chunee, revealed proteins with fundamental roles in cellular recognition. G. diazotrophicus presented proteins involved in adaptation to atypical conditions and signaling systems during the interaction with both genotypes. However, SP70-1143 and Chunee, sugarcane genotypes with high and low contribution of biological nitrogen fixation, showed divergent responses in contact with G. diazotrophicus. The SP70-1143 genotype overexpressed proteins from signaling cascades and one from a lipid metabolism pathway, whereas Chunee differentially synthesized proteins involved in chromatin remodeling and protein degradation pathways. In addition, we have identified 30 bacterial proteins in the roots of the plant samples; from those, nine were specifically induced by plant signals. This is the first quantitative proteomic analysis of a bacterium–plant interaction, which generated insights into early signaling of the G. diazotrophicus–sugarcane interaction.

© 2011 The American Phytopathological Society