A Proteomic Approach of Bradyrhizobium/Aeschynomene Root and Stem Symbioses Reveals the Importance of the fixA Locus for Symbiosis

International Journal of Molecular Sciences

Nathanael Delmotte¹  Samuel Mondy²  Benoit Alunni²  Joel Fardoux³  Clémence Chaintreuil³  Julia A. Vorholt¹  Eric Giraud³ 

[1] Institute of Microbiology, Eidgenössische Technische Hochschule (ETH) Zurich, Vladimir-Prelog-Weg 4, 8093 Zurich, Switzerland; E-Mails:;Institut des Sciences du Végétal, CNRS, 91198 Gif sur Yvette, France; E-Mails:;Laboratoire des Symbioses Tropicales et Méditerranéennes, IRD, UMR IRD/SupAgro/INRA/UM2/CIRAD, F-34398 Montpellier, France; E-Mails:

关键词: proteome;    photosynthetic Bradyrhizobium;    symbiotic nitrogen fixation;    stem nodulation;    fixA;   

DOI  :  10.3390/ijms15033660

来源: mdpi

【 摘 要 】

Rhizobia are soil bacteria that are able to form symbiosis with plant hosts of the legume family. These associations result in the formation of organs, called nodules in which bacteria fix atmospheric nitrogen to the benefit of the plant. Most of our knowledge on the metabolism and the physiology of the bacteria during symbiosis derives from studying roots nodules of terrestrial plants. Here we used a proteomics approach to investigate the bacterial physiology of photosynthetic Bradyrhizobium sp. ORS278 during the symbiotic process with the semi aquatical plant Aeschynomene indica that forms root and stem nodules. We analyzed the proteomes of bacteria extracted from each type of nodule. First, we analyzed the bacteroid proteome at two different time points and found only minor variation between the bacterial proteomes of 2-week- and 3-week-old nodules. High conservation of the bacteroid proteome was also found when comparing stem nodules and root nodules. Among the stem nodule specific proteins were those related to the phototrophic ability of Bradyrhizobium sp. ORS278. Furthermore, we compared our data with those obtained during an extensive genetic screen previously published. The symbiotic role of four candidate genes which corresponding proteins were found massively produced in the nodules but not identified during this screening was examined. Mutant analysis suggested that in addition to the EtfAB system, the fixA locus is required for symbiotic efficiency.

【 授权许可】

CC BY   
© 2014 by the authors; licensee MDPI, Basel, Switzerland