Host Plant Compatibility Shapes the Proteogenome of Frankia coriariae

Abstract

Molecular signaling networks in the actinorhizal rhizosphere select host-compatible Frankia strains, trigger the infection process and eventually the genesis of nitrogen-fixing nodules. The molecular triggers involved remain difficult to ascertain. Root exudates (RE) are highly dynamic substrates that play key roles in establishing the rhizosphere microbiome. RE are known to induce the secretion by rhizobia of Nod factors, polysaccharides, and other proteins in the case of legume symbiosis. Next-generation proteomic approach was here used to decipher the key bacterial signals matching the first-step recognition of host plant stimuli upon treatment of Frankia coriariae strain BMG5.1 with RE derived from compatible (Coriaria myrtifolia), incompatible (Alnus glutinosa), and non-actinorhizal (Cucumis melo) host plants. The Frankia proteome dynamics were mainly driven by host compatibility. Both metabolism and signal transduction were the dominant activities for BMG5.1 under the different RE conditions tested. A second set of proteins that were solely induced by C. myrtifolia RE and were mainly linked to cell wall remodeling, signal transduction and host signal processing activities. These proteins may footprint early steps in receptive recognition of host stimuli before subsequent events of symbiotic recruitment.

Proteogenomics data for deciphering Frankia coriariae interactions with root exudates from three host plants

“…After ten days of cultivation, cells were supplanted with an equal volume of root exudates from each plant species that was previously filter sterilized. The cells were incubated for five additional days as described [1] . Cells were harvested by centrifugation.…”

“…MS/MS spectra were assigned with two protein sequence databases derived from the closely-related genomes from strains BMG5.1 andDg1, the Frankia symbiont of Datisca glomerata . The tandem mass spectrometry data accompanying the manuscript describing the database searches and comparative analysis (Ktari et al, 2017, doi.org/10.3389/fmicb.2017.00720) [1] have been deposited to the ProteomeXchange with identifiers PXD005979 (whole cell proteomes) and PXD005980 (exoproteome data).…”

“… The data have been exploited to decipher the main proteome changes in response to various root exudates. As described in detail in the accompanying manuscript [1] , the proteins which are solely induced by Coriaria myrtifolia root exudates are involved in cell wall remodeling, signal transduction and host signals processing. …”

Plant–Microbe Symbiosis: What Has Proteomics Taught Us?

“…Ktari et al . used a next‐generation proteomics approach to uncover the key bacterial proteins involved in the early recognition of F. coriariae , with compatible ( Coriaria myrtifolia ), incompatible (Alnus glutinosa ), and non‐Actinorhizal host plants ( Cucumis melo ).…”

Permanent draft genome sequence of Frankia sp. NRRL B-16219 reveals the presence of canonical nod genes, which are highly homologous to those detected in Candidatus Frankia Dg1 genome

“…This symbiotic association has drawn interest because of its higher rate of soil nitrogen input and the ability of the plants to overcome harsh environmental conditions [ 2 ]. The molecular mechanism for the establishment of an actinorhizal nitrogen-fixing root nodule remains elusive [ 3 ]. Molecular phylogeny of the 10.1601/nm.7635 genus has consistently identified four main clusters regardless of the typing locus used [ 1 ].…”