A Peanut Nodule Lectin in Infected Cells and in Vacuoles and the Extracellular Matrix of Nodule Parenchyma

VandenBosch, Kathryn A.; Rodgers, L. R.; Sherrier, D. Janine; Kishinevsky, B.

doi:10.1104/pp.104.2.327

Cited by 39 publications

(22 citation statements)

References 29 publications

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“…In Dolichos biflorus, a Nod factor-binding lectin with apyrase activity is localized to root hairs (Etzler et al, 1999;Kalsi and Etzler, 2000). Lectins have been found in nodules of several species (VandenBosch et al, 1994;Bauchrowitz et al, 1996;Kardailsky et al, 1996), and alfalfa plants expressing antisense versions of noduleenhanced lectins show severe developmental defects (Brill et al, 2001). Previously studied lectins should be assessed for their induction pattern in plant mutants and in wild-type plants inoculated with bacterial mutants to determine whether they show similar expression patterns to MtLEC4.…”

Section: Discussionmentioning

confidence: 99%

Plant and Bacterial Symbiotic Mutants Define Three Transcriptionally Distinct Stages in the Development of the Medicago truncatula/Sinorhizobium meliloti Symbiosis

2004

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In the Medicago truncatula/Sinorhizobium meliloti symbiosis, the plant undergoes a series of developmental changes simultaneously, creating a root nodule and allowing bacterial entry and differentiation. Our studies of plant genes reveal novel transcriptional regulation during the establishment of the symbiosis and identify molecular markers that distinguish classes of plant and bacterial symbiotic mutants. We have identified three symbiotically regulated plant genes encoding a ␤,1-3 endoglucanase (MtBGLU1), a lectin (MtLEC4), and a cysteine-containing protein (MtN31). MtBGLU1 is down-regulated in the plant 24 h after exposure to the bacterial signal, Nod factor. The non-nodulating plant mutant dmi1 is defective in the ability to down-regulate MtBGLU1. MtLEC4 and MtN31 are induced 1 and 2 weeks after bacterial inoculation, respectively. We examined the regulation of these two genes and three previously identified genes (MtCAM1, ENOD2, and MtLB1) in plant symbiotic mutants and wild-type plants inoculated with bacterial symbiotic mutants. Plant (bit1, rit1, and Mtsym1) and bacterial (exoA and exoH) mutants with defects in the initial stages of invasion are unable to induce MtLEC4, MtN31, MtCAM1, ENOD2, and MtLB1. Bacterial mutants (fixJ and nifD) and a subset of plant mutants (dnf2, dnf3, dnf4, dnf6, and dnf7) defective for nitrogen fixation induce the above genes. The bacA bacterial mutant, which senesces upon deposition into plant cells, and two plant mutants with defects in nitrogen fixation (dnf1 and dnf5) induce MtLEC4 and ENOD2 but not MtN31, MtCAM1, or MtLB1. These data suggest the presence of at least three transcriptionally distinct developmental stages during invasion of M. truncatula by S. meliloti.The two partners in the legume-Rhizobium symbiosis navigate a complex developmental pathway, resulting in the formation of a plant-derived root nodule in which bacteria reside and reduce molecular nitrogen for use by the plant. Nodulation initiates with chemical signaling between the plant and the bacteria; the plant secretes flavonoid molecules into the rhizosphere, and the bacteria respond with lipochitooligosaccharide signaling molecules termed Nod factors (Long, 1996). The plant responds to bacterial Nod factors by initiating cortical cell divisions to build the nodule. Rhizobia enter the plant through a tubular plant-derived structure constructed in the root hair termed the infection thread (Bauer, 1981). Once the infection thread reaches the inner cortical cells of the plant, the bacteria are released into the plant cell, encapsulated in plant membranes. Within these symbiosomes, the bacteria differentiate into bacteroids that in the presence of low oxygen tension express the proteins necessary to reduce molecular nitrogen into ammonia for transport to the plant (Oke and Long, 1999b).Bacterial mutants have revealed distinct developmental signals and stages in the progression of the symbiosis. Bacterial mutants that cannot provoke the cell divisions necessary for nodule formation (Nod Ϫ ) have defects in...

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Section: Discussionmentioning

confidence: 99%

Plant and Bacterial Symbiotic Mutants Define Three Transcriptionally Distinct Stages in the Development of the Medicago truncatula/Sinorhizobium meliloti Symbiosis

2004

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“…If lectin(s) are involved in masking Nod-factors (see Section 5), then lectin molecules may also be present in the peribacteroid space (VandenBosch et al, 1994).…”

Section: Future Perspectivesmentioning

confidence: 99%

A simple model based on known plant defence reactions is sufficient to explain most aspects of nodulation

Mellor¹,

Collinge²

1995

J Exp Bot

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We present the following hypothesis; that lipooligochitin Nod-factors can act in an elicitor-like fashion inducing, amongst other effects, a plant chitolytic enzyme, capable of hydrolysing the oligochitin chain of the Nod-factor. Decorative groups on the oligochitin chain, e.g. sulphate, may confer partial resistance to hydrolysis upon particular Nod-factors. After entry into the plant, Nod-factor synthesis must be downregulated in order to avoid further, unwanted, elicitation and the consequent abortion of the symbiosis. The plant-derived compounds inhibiting the synthesis of bacterial Nod-factors are limiting in root tissue, leading to residual elicitation and the abortion of infection thread formation. Nod-gene anti-induction is, furthermore, inactivated by both light and nitrate, thus contributing to the inhibition of nodulation under these conditions. In nitrogen-fixing nodules, the bacteroids are exposed to both nod-gene inducing and repressing compounds. The slow accumulation of Nod-factors within the peribacteroid space eventually results in the elicitation of phytoalexin synthesis and nodule senescence.

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“…hypogaea were grown in greenhouse conditions and induced to form nodules as in VandenBosch et al (1994). Nodules and foliage were collected at 7, 14, 21 d post-inoculation with B. japonicum NC92.…”

Section: Plant Materialsmentioning

confidence: 99%

MicroRNAs as master regulators of the plant NB-LRR defense gene family via the production of phased, trans-acting siRNAs

Zhai¹,

Jeong²,

Paoli³

et al. 2011

Genes Dev.

632

824

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Legumes and many nonleguminous plants enter symbiotic interactions with microbes, and it is poorly understood how host plants respond to promote beneficial, symbiotic microbial interactions while suppressing those that are deleterious or pathogenic. Trans-acting siRNAs (tasiRNAs) negatively regulate target transcripts and are characterized by siRNAs spaced in 21-nucleotide (nt) ''phased'' intervals, a pattern formed by DICER-LIKE 4 (DCL4) processing. A search for phased siRNAs (phasiRNAs) found at least 114 Medicago loci, the majority of which were defense-related NB-LRR-encoding genes. We identified three highly abundant 22-nt microRNA (miRNA) families that target conserved domains in these NB-LRRs and trigger the production of trans-acting siRNAs. High levels of small RNAs were matched to >60% of all~540 encoded Medicago NB-LRRs; in the potato, a model for mycorrhizal interactions, phasiRNAs were also produced from NB-LRRs. DCL2 and SGS3 transcripts were also cleaved by these 22-nt miRNAs, generating phasiRNAs, suggesting synchronization between silencing and pathogen defense pathways. In addition, a new example of apparent ''two-hit'' phasiRNA processing was identified. Our data reveal complex tasiRNA-based regulation of NB-LRRs that potentially evolved to facilitate symbiotic interactions and demonstrate miRNAs as master regulators of a large gene family via the targeting of highly conserved, protein-coding motifs, a new paradigm for miRNA function.

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A Peanut Nodule Lectin in Infected Cells and in Vacuoles and the Extracellular Matrix of Nodule Parenchyma

Cited by 39 publications

References 29 publications

Plant and Bacterial Symbiotic Mutants Define Three Transcriptionally Distinct Stages in the Development of the Medicago truncatula/Sinorhizobium meliloti Symbiosis

Plant and Bacterial Symbiotic Mutants Define Three Transcriptionally Distinct Stages in the Development of the Medicago truncatula/Sinorhizobium meliloti Symbiosis

A simple model based on known plant defence reactions is sufficient to explain most aspects of nodulation

MicroRNAs as master regulators of the plant NB-LRR defense gene family via the production of phased, trans-acting siRNAs

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