Rhizobium meliloti elicits transient expression of the early nodulin gene ENOD12 in the differentiating root epidermis of transgenic alfalfa.

Pichon, Magalie; Journet, Etienne-Pascal; Dedieu, Annie; Billy, Françoise de; Truchet, G.; Barker, David G.

doi:10.1105/tpc.4.10.1199

Cited by 176 publications

(126 citation statements)

References 38 publications

(43 reference statements)

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“…At least 47% of the ESTs in each of TC28588, TC29418, TC28970, TC36450, TC29982, TC28429, TC37466, TC33130, and TC35962 came from the MtBB library, indicating that they are early nodulins induced before the onset of N 2 fixation (Nap and Bisseling, 1990). In previous studies (Pichon et al, 1992;Gamas et al, 1996;Greene et al, 1998), these nodulins were also described as being induced early in nodule development. In comparison, among the 660 Lb ESTs sequenced, only three ESTs originate from the MtBB early nodule library.…”

Section: Characterization Of Nodule-specific Tcsmentioning

confidence: 99%

Genome-Wide Identification of Nodule-Specific Transcripts in the Model Legume Medicago truncatula

et al. 2002

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The Medicago truncatula expressed sequence tag (EST) database (Gene Index) contains over 140,000 sequences from 30 cDNA libraries. This resource offers the possibility of identifying previously uncharacterized genes and assessing the frequency and tissue specificity of their expression in silico. Because M. truncatula forms symbiotic root nodules, unlike Arabidopsis, this is a particularly important approach in investigating genes specific to nodule development and function in legumes. Our analyses have revealed 340 putative gene products, or tentative consensus sequences (TCs), expressed solely in root nodules. These TCs were represented by two to 379 ESTs. Of these TCs, 3% appear to encode novel proteins, 57% encode proteins with a weak similarity to the GenBank accessions, and 40% encode proteins with strong similarity to the known proteins. Nodule-specific TCs were grouped into nine categories based on the predicted function of their protein products. Besides previously characterized nodulins, other examples of highly abundant nodule-specific transcripts include plantacyanin, agglutinin, embryo-specific protein, and purine permease. Six nodule-specific TCs encode calmodulin-like proteins that possess a unique cleavable transit sequence potentially targeting the protein into the peribacteroid space. Surprisingly, 114 nodule-specific TCs encode small Cys cluster proteins with a cleavable transit peptide. To determine the validity of the in silico analysis, expression of 91 putative nodule-specific TCs was analyzed by macroarray and RNA-blot hybridizations. Nodule-enhanced expression was confirmed experimentally for the TCs composed of five or more ESTs, whereas the results for those TCs containing fewer ESTs were variable. , and organ development (Ruan et al., 1998;Girke et al., 2000; Zhu and Wang, 2000). Although Arabidopsis serves as the model system for most plant processes, it suffers from two major weaknesses in consideration of plant-microbe interactions: the absence of symbiotic associations with mycorrhizal fungi and with rhizobia.In recent years, Medicago truncatula and Lotus japonicus have emerged as model systems for genomic approaches to plant-microbe symbiotic associations (Barker et al., 1990;Handberg and Stougaard, 1992; Cook et al., 1997; Cook, 1999;Oldroyd and Geurts, 2001;Thoquet et al., 2002). Both species possess small genomes, are diploid, have fast generation times, and can be transformed with Agrobacterium tumefaciens and regenerated (Handberg and Stougaard, 1992; Blondon et al., 1994;Handberg et al., 1994; Chabaud et al., 1996;Jiang and Gresshoff, 1997;Stiller et al., 1997;Trinh et al., 1998;Trieu et al., 2000). Currently, both functional and structural genomics approaches are being pursued within each of these species. Covitz et al. (1998) reported the sequencing of about 900 cDNA tags from the M. truncatula root hairs. In addition, hundreds more expressed sequence tags (ESTs) have been isolated and characterized from effective root nodules of L. japonicus and M. truncatula, and a ...

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Section: Characterization Of Nodule-specific Tcsmentioning

confidence: 99%

Genome-Wide Identification of Nodule-Specific Transcripts in the Model Legume Medicago truncatula

et al. 2002

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“…therein). The perception of Nod factors and subsequent nodule development also modify the root transcriptional program, with gene induction observed as early as 3 h post inoculation (hpi; Pichon et al, 1992;Cook et al, 1995).…”

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confidence: 99%

Deep Sequencing of the Medicago truncatula Root Transcriptome Reveals a Massive and Early Interaction between Nodulation Factor and Ethylene Signals

et al. 2015

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The legume-rhizobium symbiosis is initiated through the activation of the Nodulation (Nod) factor-signaling cascade, leading to a rapid reprogramming of host cell developmental pathways. In this work, we combine transcriptome sequencing with molecular genetics and network analysis to quantify and categorize the transcriptional changes occurring in roots of Medicago truncatula from minutes to days after inoculation with Sinorhizobium medicae. To identify the nature of the inductive and regulatory cues, we employed mutants with absent or decreased Nod factor sensitivities (i.e. Nodulation factor perception and Lysine motif domain-containing receptor-like kinase3, respectively) and an ethylene (ET)-insensitive, Nod factor-hypersensitive mutant (sickle). This unique data set encompasses nine time points, allowing observation of the symbiotic regulation of diverse biological processes with high temporal resolution. Among the many outputs of the study is the early Nod factorinduced, ET-regulated expression of ET signaling and biosynthesis genes. Coupled with the observation of massive transcriptional derepression in the ET-insensitive background, these results suggest that Nod factor signaling activates ET production to attenuate its own signal. Promoter:b-glucuronidase fusions report ET biosynthesis both in root hairs responding to rhizobium as well as in meristematic tissue during nodule organogenesis and growth, indicating that ET signaling functions at multiple developmental stages during symbiosis. In addition, we identified thousands of novel candidate genes undergoing Nod factor-dependent, ET-regulated expression. We leveraged the power of this large data set to model Nod factor-and ET-regulated signaling networks using MERLIN, a regulatory network inference algorithm. These analyses predict key nodes regulating the biological process impacted by Nod factor perception. We have made these results available to the research community through a searchable online resource.

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“…For simple GUS stainings only X-D-glcA was utilized. For whole root observations (except for Figure la) and for microtome sections of 80-200 mm (Micro-Cut H1200, Bio-Rad), the material was cleared as desribed by Pichon et al (1992). Starch was stained using a lugol solution containing 1% iodine and 1% potassium iodide, and subsequently washed.…”

Section: Histochemical Localization Of Gus and #-Gal Activity Microsmentioning

confidence: 99%

Nod factors and cytokinins induce similar cortical cell division, amyloplast deposition and MsEnod12A expression patterns in alfalfa roots

et al. 1996

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SummaryUnder nitrogen limitation, Rhizobium meliloti Nod factors induce cell divisions in the inner cortex of alfalfa roots in a still unknown way. These cell division clusters subsequently develop into symbiotically nitrogen-fixing nodules. To study the involvement of plant signals in nodule initiation transgenic alfalfa carrying the promoter of the early nodulin gene MsEnod12A fused to the reporter gene gusA were generated. In untreated plants, low level GUS staining was only found in lateral root primordia and in front of the root apices. After inoculation with R. meliloti or after treatment with purified Nod factors, GUS activity was first induced in the cell division foci of the inner cortex. The GUS staining patterns in nodules and roots were in agreement with the activation of the endogenous MsEnod12A gene as revealed by reverse transcription-PCR analysis, rendering the MsEnod12A-gusA fusion a valuable novel marker for studying the onset of nodule and lateral root developmental processes. Treatment of roots with purified Nod factors and cytokinins induced similar patterns of cortical cell division, GUS staining and amyloplast accumulation while upon application of auxin transport inhibitors and auxins these patterns were different. Like the Nod factor responses, the cytokinin responses required photosynthesis and limiting combined nitrogen supply. Thus, cytokinins and Nod factors may share elements of their signal transduction pathways to the inner root cortex. A model on the possible involvement of cytokinins in coordinating plant metabolism with nodule initiation is proposed.

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Rhizobium meliloti elicits transient expression of the early nodulin gene ENOD12 in the differentiating root epidermis of transgenic alfalfa.

Cited by 176 publications

References 38 publications

Genome-Wide Identification of Nodule-Specific Transcripts in the Model Legume Medicago truncatula

Genome-Wide Identification of Nodule-Specific Transcripts in the Model Legume Medicago truncatula

Deep Sequencing of the Medicago truncatula Root Transcriptome Reveals a Massive and Early Interaction between Nodulation Factor and Ethylene Signals

Nod factors and cytokinins induce similar cortical cell division, amyloplast deposition and MsEnod12A expression patterns in alfalfa roots

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