DELLA proteins are common components of symbiotic rhizobial and mycorrhizal signalling pathways.
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ABSTRACT:
SUBMITTER: Jin Y
PROVIDER: S-EPMC4990646 | biostudies-literature | 2016 Aug
REPOSITORIES: biostudies-literature
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DELLA proteins are common components of symbiotic rhizobial and mycorrhizal signalling pathways.
Jin Yue Y Liu Huan H Luo Dexian D Yu Nan N Dong Wentao W Wang Chao C Zhang Xiaowei X Dai Huiling H Yang Jun J Wang Ertao E
Nature communications 20160812
Legumes form symbiotic associations with either nitrogen-fixing bacteria or arbuscular mycorrhizal fungi. Formation of these two symbioses is regulated by a common set of signalling components that act downstream of recognition of rhizobia or mycorrhizae by host plants. Central to these pathways is the calcium and calmodulin-dependent protein kinase (CCaMK)-IPD3 complex which initiates nodule organogenesis following calcium oscillations in the host nucleus. However, downstream signalling events ...[more]
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Project description:Legumes develop symbiotic interactions with rhizobial bacteria to form nitrogen-fixing nodules. Bacterial Nod factors (NFs) and plant regulatory pathways modulating NF signalling control rhizobial infections and nodulation efficiency. Here we show that gibberellin (GA) signalling mediated by DELLA proteins inhibits rhizobial infections and controls the NF induction of the infection marker ENOD11 in Medicago truncatula. Ectopic expression of a constitutively active DELLA protein in the epidermis is sufficient to promote ENOD11 expression in the absence of symbiotic signals. We show using heterologous systems that DELLA proteins can interact with the nodulation signalling pathway 2 (NSP2) and nuclear factor-YA1 (NF-YA1) transcription factors that are essential for the activation of NF responses. Furthermore, MtDELLA1 can bind the ERN1 (ERF required for nodulation 1) promoter and positively transactivate its expression. Overall, we propose that GA-dependent action of DELLA proteins may directly regulate the NSP1/NSP2 and NF-YA1 activation of ERN1 transcription to regulate rhizobial infections.
| S-EPMC5025792 | biostudies-literature
Project description:Most flowering plants are able to form endosymbioses with arbuscular mycorrhizal fungi. In this mutualistic association, the fungus colonizes the root cortex and establishes elaborately branched hyphae, called arbuscules, within the cortical cells. Arbuscule development requires the cellular reorganization of both symbionts, and the resulting symbiotic interface functions in nutrient exchange. A plant symbiosis signaling pathway controls the development of the symbiosis. Several components of the pathway have been identified, but transcriptional regulators that control downstream pathways for arbuscule formation are still unknown. Here we show that DELLA proteins, which are repressors of gibberellic acid (GA) signaling and function at the nexus of several signaling pathways, are required for arbuscule formation. Arbuscule formation is severely impaired in a Medicago truncatula Mtdella1/Mtdella2 double mutant; GA treatment of wild-type roots phenocopies the della double mutant, and a dominant DELLA protein (della1-Δ18) enables arbuscule formation in the presence of GA. Ectopic expression of della1-Δ18 suggests that DELLA activity in the vascular tissue and endodermis is sufficient to enable arbuscule formation in the inner cortical cells. In addition, expression of della1-Δ18 restores arbuscule formation in the symbiosis signaling pathway mutant cyclops/ipd3, indicating an intersection between DELLA and symbiosis signaling for arbuscule formation. GA signaling also influences arbuscule formation in monocots, and a Green Revolution wheat variety carrying dominant DELLA alleles shows enhanced colonization but a limited growth response to arbuscular mycorrhizal symbiosis.
| S-EPMC3870710 | biostudies-literature
Project description:Primary infection of legumes by rhizobia involves the controlled localized enzymatic breakdown of cell walls at root hair tips. Previous studies determined the role of rhizobial CelC2 cellulase in different steps of the symbiotic interaction Rhizobium leguminosarum-Trifolium repens. Recent findings also showed that CelC2 influences early signalling events in the Ensifer meliloti-Medicago truncatula interaction. Here, we have monitored the root hair phenotypes of two legume plants, T. repens and M. sativa, upon inoculation with strains of their cognate and non-cognate rhizobial species, R. leguminosarum bv trifolii and E. meliloti, (over)expressing the CelC2 coding gene, celC. Regardless of the host, CelC2 specifically elicited 'hole-on-the-tip' events (Hot phenotype) in the root hair apex, consistent with the role of this endoglucanase in eroding the noncrystalline cellulose found in polarly growing cell walls. Overproduction of CelC2 also increased root hair tip redirections (RaT phenotype) events in both cognate and non-cognate hosts. Interestingly, heterologous celC expression also induced non-canonical alterations in ROS (Reactive Oxygen Species) homeostasis at root hair tips of Trifolium and Medicago. These results suggest the concurrence of shared unspecific and host-related plant responses to CelC2 during early steps of symbiotic rhizobial infection. Our data thus identify CelC2 cellulase as an important determinant of events underlying early infection of the legume host by rhizobia.
| S-EPMC6761101 | biostudies-literature
Project description:Specific complex interactions between soil bacteria belonging to Rhizobium, Sinorhizobium, Mesorhizobium, Phylorhizobium, Bradyrhizobium and Azorhizobium commonly known as rhizobia, and their host leguminous plants result in development of root nodules. Nodules are new organs that consist mainly of plant cells infected with bacteroids that provide the host plant with fixed nitrogen. Proper nodule development requires the synthesis and perception of signal molecules such as lipochitooligosaccharides, called Nod factors that are important for induction of nodule development. Bacterial surface polysaccharides are also crucial for establishment of successful symbiosis with legumes. Sugar polymers of rhizobia are composed of a number of different polysaccharides, such as lipopolysaccharides (LPS), capsular polysaccharides (CPS or K-antigens), neutral beta-1, 2-glucans and acidic extracellular polysaccharides (EPS). Despite extensive research, the molecular function of the surface polysaccharides in symbiosis remains unclear. This review focuses on exopolysaccharides that are especially important for the invasion that leads to formation of indetermined (with persistent meristem) type of nodules on legumes such as clover, vetch, peas or alfalfa. The significance of EPS synthesis in symbiotic interactions of Rhizobium leguminosarum with clover is especially noticed. Accumulating data suggest that exopolysaccharides may be involved in invasion and nodule development, bacterial release from infection threads, bacteroid development, suppression of plant defense response and protection against plant antimicrobial compounds. Rhizobial exopolysaccharides are species-specific heteropolysaccharide polymers composed of common sugars that are substituted with non-carbohydrate residues. Synthesis of repeating units of exopolysaccharide, their modification, polymerization and export to the cell surface is controlled by clusters of genes, named exo/exs, exp or pss that are localized on rhizobial megaplasmids or chromosome. The function of these genes was identified by isolation and characterization of several mutants disabled in exopolysaccharide synthesis. The effect of exopolysaccharide deficiency on nodule development has been extensively studied. Production of exopolysaccharides is influenced by a complex network of environmental factors such as phosphate, nitrogen or sulphur. There is a strong suggestion that production of a variety of symbiotically active polysaccharides may allow rhizobial strains to adapt to changing environmental conditions and interact efficiently with legumes.
| S-EPMC1403797 | biostudies-literature
Project description:BackgroundRhizobia are alpha-proteobacteria commonly found in soil and root nodules of legumes. It was recently reported that nitrogen-fixing rhizobia also inhabit legume seeds. In this study, we examined whole-genome sequences of seven strains of rhizobia isolated from seeds of common bean (Phaseolus vulgaris).ResultsRhizobial strains included in this study belonged to three different species, including Rhizobium phaseoli, R. leguminosarum, and R. grahamii. Genome sequence analyses revealed that six of the strains formed three pairs of highly related strains. Both strains comprising a pair shared all but one plasmid. In two out of three pairs, one of the member strains was effective in nodulation and nitrogen fixation, whereas the other was ineffective. The genome of the ineffective strain in each pair lacked several genes responsible for symbiosis, including nod, nif, and fix genes, whereas that of the effective strain harbored the corresponding genes in clusters, suggesting that recombination events provoked gene loss in ineffective strains. Comparisons of genomic sequences between seed strains and nodule strains of the same species showed high conservation of chromosomal sequences and lower conservation of plasmid sequences. Approximately 70% of all genes were shared among the strains of each species. However, paralogs were more abundant in seed strains than in nodule strains. Functional analysis showed that seed strains were particularly enriched in genes involved in the transport and metabolism of amino acids and carbohydrates, biosynthesis of cofactors and in transposons and prophages. Genomes of seed strains harbored several intact prophages, one of which was inserted at exactly the same genomic position in three strains of R. phaseoli and R. leguminosarum. The R. grahamii strain carried a prophage similar to a gene transfer agent (GTA); this represents the first GTA reported for this genus.ConclusionsSeeds represent a niche for bacteria; their access by rhizobia possibly triggered the infection of phages, recombination, loss or gain of plasmids, and loss of symbiosis genes. This process probably represents ongoing evolution that will eventually convert these strains into obligate endophytes.
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Project description:Around two-thirds of all plant species form arbuscular mycorrhizasa symbiosis between plant roots and glomalean fungi that leads to the formation of intraradical organs of nutrient exchange and an extraradical network of fungal hyphae effectively extending the plant root system. The mycorrhiza plays a key role in plant nutrition and in enhancing plant resistance against pathogens and improving drought resistance. At present very little is known about the molecular basis of arbuscular mycorrhiza formation. Arabidopsis thaliana (as with all Brassicaceae) does not form arbuscular mycorrhizas (AM). Arabidopsis may either have lost essential gene functions or acquired new ones that prevent a successful symbiotic interaction. However given that mycorrhizal symbiosis developed very early during the evolution of land plants and that many ectomycorrhizal plant species can be colonised by AM fungi it is likely that important components of AM signalling pathways are conserved in all plants including Arabidopsis. Possibly the lack of AM development is a multigenic trait and this would make it difficult to isolate mutants that (re-)gain the ability to interact with AM fungi. What can be done however is firstly to test which parts of one or several putative AM signalling pathways are still functional and which ones are not. Secondly we can test whether negatively acting pathways such as those involved in defence against pathogenic microorganisms are induced upon inoculation with AM fungi. Together this work is likely to give important information of why Arabidopsis (and Brassicaceae) are behaving as non-hosts for AM fungi. In other words Arabidopsis will be an ideal system to study mechanisms of non-host "resistance" to AM colonisation. Elucidating these mechanisms will obviously make a great contribution to understanding the basis of the mycorrhizal interaction. Moreover using Arabidopsis as a tool it will be possible at the end to integrate the information obtained for AM signalling with that obtained for other developmental and environmentally triggered signalling pathways such as plant hormone signalling or plant defence responses. To produce an inventory of which Arabidopsis genes respond at all to inoculation with AM fungi a genome-wide screen for AM-controlled genes is proposed. RNA will be prepared from Arabidopsis roots treated with AM fungus and mock-inoculated control plants. Arabidopsis (Col-0) will be grown in pot culture (1:1 sand/Terra-Green) at low concentrations of phosphate. Three week-old plants will be inoculated with surface-sterilised spores of Gigaspora rosea. RNA will be isolated 3 days post inoculation. Experimenter name: Hsiu-Ling Yap Experimenter phone: 01904 434 302/304 Experimenter fax: 01904 434 312 Experimenter institute: University of York Experimenter address: Department of Biology University of York P.O.Box 373 York!Series_summary = Experimenter zip/postal_code: YO10 5YW Experimenter country: UK Keywords: compound_treatment_design
2008-01-31 | GSE10323 | GEO
Project description:Plant species posses a special set of genes functional only in arbuscular mycorrhizal symbiosis. So, the model plant Medicago truncatula (Jemalong 5) was used for transcriptome comparative analysis while infected with compatible rhizobia Sinorhizobium meliloti (strain 10) and with or without arbuscular mycorrhizal fungus Rhizophagus irregularis (SYM5). Whole shoot and whole root were used for RNA isolation and processed via one of the European certified Affymetrix core labs (http://core.img.cas.cz).
2019-04-21 | GSE126833 | GEO
Project description:Legume plants form symbiotic associations with either nitrogen-fixing bacteria or arbuscular mycorrhizal (AM) fungi, which are regulated by a set of common symbiotic signaling pathway genes. Central to the signaling pathway is the activation of the DMI3/IPD3 protein complex by Ca2+ oscillations, and the initiation of nodule organogenesis and mycorrhizal symbiosis. DMI3 is essential for rhizobial infection and nodule organogenesis; however, ipd3 mutants have been shown to be impaired only in infection thread formation but not in root nodule organogenesis in Medicago truncatula. We identified an IPD3-like (IPD3L) gene in the M. truncatula genome. A single ipd3l mutant exhibits a normal root nodule phenotype. The ipd3l/ipd3-2 double mutant is completely unable to initiate infection threads and nodule primordia. IPD3L can functionally replace IPD3 when expressed under the control of the IPD3 promoter, indicating functional redundancy between these two transcriptional regulators. We constructed a version of IPD3 that was phosphomimetic with respect to two conserved serine residues (IPD3-2D). This was sufficient to trigger root nodule organogenesis, but the increased multisite phosphorylation of IPD3 (IPD3-8D) led to low transcriptional activity, suggesting that the phosphorylation levels of IPD3 fine-tune its transcriptional activity in the root nodule symbiosis. Intriguingly, the phosphomimetic version of IPD3 triggers spontaneous root-like nodules on the roots of dmi3-1 and dmi2-1 (DMI2 is an LRR-containing receptor-like kinase gene which is required for Ca2+ spiking), but not on the roots of wild-type or ipd3l ipd3-2 plants. In addition, fully developed arbuscules were formed in the ipd3l ipd3-2 mutants but not the ccamk/dmi3-1 mutants. Collectively, our data indicate that, in addition to IPD3 and IPD3L, another new genetic component or other new phosphorylation sites of IPD3 function downstream of DMI3 in rhizobial and mycorrhizal symbioses.
| S-EPMC5865340 | biostudies-literature
Project description:In the Medicago truncatula-Sinorhizobium meliloti symbiosis, chemical signaling initiates rhizobial infection of root nodule tissue, where a large portion of the bacteria are endocytosed into root nodule cells to function in nitrogen-fixing organelles. These intracellular bacteria are subjected to an arsenal of plant-derived nodule-specific cysteine-rich (NCR) peptides, which induce the physiological changes that accompany nitrogen fixation. NCR peptides drive these intracellular bacteria toward terminal differentiation. The bacterial peptidase HrrP was previously shown to degrade host-derived NCR peptides and give the bacterial symbionts greater fitness at the expense of host fitness. The hrrP gene is found in roughly 10% of Sinorhizobium isolates, as it is carried on an accessory plasmid. The objective of the present study is to identify peptidase genes in the core genome of S. meliloti that modulate symbiotic outcome in a manner similar to the accessory hrrP gene. In an overexpression screen of annotated peptidase genes, we identified one such symbiosis-associated peptidase (sap) gene, sapA (SMc00451). When overexpressed, sapA leads to a significant decrease in plant fitness. Its promoter is active in root nodules, with only weak expression evident under free-living conditions. The SapA enzyme can degrade a broad range of NCR peptides in vitro.
| S-EPMC8175422 | biostudies-literature
Project description:DELLA transcriptional regulators are central components in the control of plant growth responses to the environment. This control is considered to be mediated by changes in the metabolism of the hormones gibberellins (GAs), which promote the degradation of DELLAs. However, here we show that warm temperature or shade reduced the stability of a GA-insensitive DELLA allele in Arabidopsis thaliana Furthermore, the degradation of DELLA induced by the warmth preceded changes in GA levels and depended on the E3 ubiquitin ligase CONSTITUTIVELY PHOTOMORPHOGENIC1 (COP1). COP1 enhanced the degradation of normal and GA-insensitive DELLA alleles when coexpressed in Nicotiana benthamiana. DELLA proteins physically interacted with COP1 in yeast, mammalian, and plant cells. This interaction was enhanced by the COP1 complex partner SUPRESSOR OF phyA-105 1 (SPA1). The level of ubiquitination of DELLA was enhanced by COP1 and COP1 ubiquitinated DELLA proteins in vitro. We propose that DELLAs are destabilized not only by the canonical GA-dependent pathway but also by COP1 and that this control is relevant for growth responses to shade and warm temperature.
| S-EPMC7306988 | biostudies-literature