Comparative secretome analysis suggests low plant cell wall degrading capacity in Frankia symbionts (original) (raw)
Related papers
Host Plant Compatibility Shapes the Proteogenome of Frankia coriariae
Frontiers in Microbiology, 2017
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.
Data in Brief
Frankia coriariae BMG5.1 cells were incubated with root exudates derived from compatible (Coriaria myrtifolia), incompatible (Alnus glutinosa) and non-actinorhizal (Cucumis melo) host plants. Bacteria cells and their exoproteomes were analyzed by high-throughput proteomics using a Q-Exactive HF high resolution tandem mass spectrometer incorporating an ultra-high-field orbitrap analyzer. 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).
Genomes of three facultatively symbiotic Frankia sp. strains reflect host plant biogeography
2006
Filamentous actinobacteria from the genus Frankia and diverse woody trees and shrubs together form N2-fixing actinorhizal root nodule symbioses that are a major source of new soil nitrogen in widely diverse biomes 1. Three major clades of Frankia sp. strains are defined; each clade is associated with a defined subset of plants from among the eight actinorhizal plant families 2,3. The evolution arytrajectories followed by the ancestors of both symbionts leading to current patterns of symbiont compatibility are unknown. Here we show that the competing processes of genome expansion and contraction have operated in different groups of Frankia strains in a manner that can be related to the speciation of the plant hosts and their geographic distribution. We sequenced and compared the genomes from three Frankia sp. strains having different host plant specificities. The sizes of their genomes varied from 5.38 Mbp for a narrow host range strain (HFPCcI3) to 7.50Mbp for a medium host range st...
Symbiosis, 2016
The actinorhizal symbiosis is a mutualistic relationship between an actinobacterium from the genus Frankia and a wide variety of dicotyledonous plants representing 8 different families of angiosperms. Molecular phylogenetic approaches have identified four major Frankia lineages that have distinctive plant host ranges. Since the first published three Frankia genomes, an effort was undertaken to provide full genomic databases covering all four well established Frankia lineages and to provide depth of the number of strains covered. Here, we report on the updated status of these sequencing efforts. At present, there are 25 complete or draft Frankia genomes that have been sequenced and annotated, and several others are now in the pipeline being sequenced. An overview of the Frankia genomes will be presented focusing on their general genomic properties including size of the pan-and core-gene pool, size relationship and genome plasticity. Furthermore, a description of biosynthetic potential and a discussion about genes (nitrogenase, hopanoid biosynthesis, truncated hemoglobin, hydrogenase uptake gene clusters) involved in the symbiosis will be discussed. The absence of common nod genes within these Frankia genomes provides clues about the host-microbe recognition process for the actinorhizal symbiosis
The New phytologist, 2018
Nitrogen-fixing filamentous Frankia colonize the root tissues of its actinorhizal host Discaria trinervis via an exclusively intercellular pathway. Here we present studies aimed at uncovering mechanisms associated with this little-researched mode of root entry, and in particular the extent to which the host plant is an active partner during this process. Detailed characterization of the expression patterns of infection-associated actinorhizal host genes has provided valuable tools to identify intercellular infection sites, thus allowing in vivo confocal microscopic studies of the early stages of Frankia colonization. The subtilisin-like serine protease gene Dt12, as well as its Casuarina glauca homolog Cg12, are specifically expressed at sites of Frankia intercellular colonization of D. trinervis outer root tissues. This is accompanied by nucleo-cytoplasmic reorganization in the adjacent host cells and major remodeling of the intercellular apoplastic compartment. These findings lead...
Actinorhizal plant defence-related genes in response to symbiotic Frankia
2011
Actinorhizal plants have become increasingly important as climate changes threaten to remake the global landscape over the next decades. These plants are able to grow in nutrient-poor and disturbed soils, and are important elements in plant communities worldwide. Besides that, most actinorhizal plants are capable of high rates of nitrogen fixation due to their capacity to establish root nodule symbiosis with N 2 -fixing Frankia strains. Nodulation is a developmental process that requires a sequence of highly coordinated events. One of these mechanisms is the induction of defence-related events, whose precise role in a symbiotic interaction remains to be elucidated. This review summarises what is known about the induction of actinorhizal defence-related genes in response to symbiotic Frankia and their putative function during symbiosis.
Proceedings of the National Academy of Sciences, 2008
Root endosymbioses vitally contribute to plant nutrition and fitness worldwide. Nitrogen-fixing root nodulation, confined to four plant orders, encompasses two distinct types of associations, the interaction of legumes (Fabales) with rhizobia bacteria and actinorhizal symbioses, where the bacterial symbionts are actinomycetes of the genus Frankia. Although several genetic components of the host-symbiont interaction have been identified in legumes, the genetic basis of actinorhiza formation is unknown. Here, we show that the receptor-like kinase gene SymRK, which is required for nodulation in legumes, is also necessary for actinorhiza formation in the tree Casuarina glauca. This indicates that both types of nodulation symbiosis share genetic components. Like several other legume genes involved in the interaction with rhizobia, SymRK is also required for the interaction with arbuscular mycorrhiza (AM) fungi. We show that SymRK is involved in AM formation in C. glauca as well and can restore both nodulation and AM symbioses in a Lotus japonicus symrk mutant. Taken together, our results demonstrate that SymRK functions as a vital component of the genetic basis for both plant-fungal and plant-bacterial endosymbioses and is conserved between legumes and actinorhiza-forming Fagales.
PLANT PHYSIOLOGY, 2011
Comparative transcriptomics of two actinorhizal symbiotic plants, Casuarina glauca and Alnus glutinosa, was used to gain insight into their symbiotic programs triggered following contact with the nitrogen-fixing actinobacterium Frankia. Approximately 14,000 unigenes were recovered in roots and 3-week-old nodules of each of the two species. A transcriptomic array was designed to monitor changes in expression levels between roots and nodules, enabling the identification of up-and downregulated genes as well as root-and nodule-specific genes. The expression levels of several genes emblematic of symbiosis were confirmed by quantitative polymerase chain reaction. As expected, several genes related to carbon and nitrogen exchange, defense against pathogens, or stress resistance were strongly regulated. Furthermore, homolog genes of the common and nodule-specific signaling pathways known in legumes were identified in the two actinorhizal symbiotic plants. The conservation of the host plant signaling pathway is all the more surprising in light of the lack of canonical nod genes in the genomes of its bacterial symbiont, Frankia. The evolutionary pattern emerging from these studies reinforces the hypothesis of a common genetic ancestor of the Fabid (Eurosid I) nodulating clade with a genetic predisposition for nodulation.
Exploring the genomes of Frankia
Physiologia Plantarum, 2007
The recent determination of the genome sequence of three Frankia strains has highlighted the evolutionary forces that have shaped the genetic makeup of the actinorhizal symbionts and it has opened up many avenues of research. Instances of gene duplication, gene loss and gene acquisition through lateral transfer show that the three Frankia genomes are dynamic and have evolved as a function of their host characteristics and biogeography. No convincing nod gene cluster or significant symbiotic island could be discerned. All the genes presently known to be involved in the symbiosis (nif, hup1 and hup2, shc) are found spread over the genome in at least four clusters. The results will be discussed with emphasis on understanding the mechanisms underlying the interaction and link between evolutionary forces and ecological adaptation to different biotopes.