Proteomic Characterization of <i>Bradyrhizobium diazoefficiens</i> Bacteroids Reveals a Post-Symbiotic, Hemibiotrophic-Like Lifestyle of the Bacteria within Senescing Soybean Nodules

• Main Authors: Kent N. Strodtman, Sooyoung Frank, Severin Stevenson, Jay J. Thelen, David W. Emerich
• Format: Article
• Language: English
• Published: MDPI AG 2018-12-01
• Series: International Journal of Molecular Sciences
• Subjects: <i>Bradyrhizobium diazoefficiens</i>; soybean; <i>Glycine max</i>; nitrogen fixation; senescence; proteomics; hemibiotroph
• Online Access: https://www.mdpi.com/1422-0067/19/12/3947

The form and physiology of <i>Bradyrhizobium diazoefficiens</i> after the decline of symbiotic nitrogen fixation has been characterized. Proteomic analyses showed that post-symbiotic <i>B. diazoefficiens</i> underwent metabolic remodeling as well-defined groups of proteins declined, increased or remained unchanged from 56 to 119 days after planting, suggesting a transition to a hemibiotrophic-like lifestyle. Enzymatic analysis showed distinct patterns in both the cytoplasm and the periplasm. Similar to the bacteroid, the post-symbiotic bacteria rely on a non-citric acid cycle supply of succinate and, although viable, they did not demonstrate the ability to grow within the senescent nodule.