Genetic analysis of calcium spiking responses in nodulation mutants of
            <i>Medicago truncatula</i>

Wais, Rebecca J.; Galera, Christine; Oldroyd, Giles; Catoira, Romy; Penmetsa, R. Varma; Cook, Douglas R.; Gough, Clare; Denarié, Jean; Long, Sharon R.

doi:10.1073/pnas.230439797

Cited by 256 publications

(265 citation statements)

References 41 publications

(49 reference statements)

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“…Genetic dissection of nodulation in M. truncatula has identified four genes that appear to have a role in Nod factor signal transduction (Catoira et al, 2000; Wais et al, 2000). Here, we describe the identification of a fifth gene NSP2.…”

Section: Discussionmentioning

confidence: 73%

“…Previous characterization of Nod Ϫ mutants for calcium spiking has indicated that dmi1 and dmi2 appear to be blocked upstream of calcium spiking, whereas dmi3 and nsp retain their ability to induce calcium spiking (Wais et al, 2000). We assessed the calcium-spiking response of nsp2-2 mutants.…”

Section: Nodulin Gene Expression Is Greatly Reduced In Nsp2 Mutantsmentioning

confidence: 98%

“…Analysis of calcium spiking was performed as described by Ehrhardt et al (1996), with slight modifications as described by Wais et al (2000). Seedlings were grown overnight on BNM.…”

Section: Calcium-spiking Experimentsmentioning

confidence: 99%

“…nodulationsignaling pathway (nsp) mutants show root hair deformation and limited gene expression, but are blocked for cortical cell induction in response to Nod factor. Analysis of the calcium-spiking responses to Nod factor in these mutants revealed that dmi1 and dmi2 mutants are blocked for the induction of calcium spiking, whereas dmi3 and nsp mutants are able to induce calcium spiking after Nod factor application (Wais et al, 2000 Article, publication date, and citation information can be found at www.plantphysiol.org/cgi …”

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confidence: 99%

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Identification and Characterization of Nodulation-Signaling Pathway 2, a Gene of Medicago truncatula Involved in Nod Factor Signaling

2003

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Bacterially derived Nod factor is critical in the establishment of the legume/rhizobia symbiosis. Understanding the mechanisms of Nod factor perception and signal transduction in the plant will greatly advance our understanding of this complex interaction. Here, we describe the identification of a new locus, nodulation-signaling pathway 2 (NSP2), of Medicago truncatula that is involved in Nod factor signaling. Mutants at this locus are blocked for Nod factor-induced gene expression and show a reduced root hair deformation response. nsp2 plants also show a complete absence of infection and cortical cell division following Sinorhizobium meliloti inoculation. Nod factor-induced calcium spiking, one of the earliest responses tested, is still functional in these mutant plants. We conclude that the gene NSP2 is a component of the Nod factor signal transduction pathway that lies downstream of the calcium-spiking response.The symbiotic interaction between legumes and rhizobial bacteria accounts for a significant portion of biological nitrogen fixation worldwide. The site of fixation is the nodule, a unique plant organ located on the root, which functions to generate the aerobic environment essential for bacterial survival and nitrogenase activity. Nodule formation involves plant/ bacterial signaling, with the bacterially generated signaling molecule Nod factor playing a critical role (Long, 1996;Downie and Walker, 1999;Oldroyd, 2001).Purified Nod factor, when applied to the appropriate plant host, can induce many of the plant responses associated with exposure to the bacterial symbiont (Downie and Walker, 1999). Nod factors act predominantly on two cell types in the root: epidermal cells and inner cortical cells. In epidermal cells, Nod factor induces depolarization of the plasma membrane, oscillations in cytosolic Ca 2ϩ referred to as calcium spiking, the induction of specific gene expression, and distortion of polar growth in root hairs (Ehrhardt et al., 1992(Ehrhardt et al., , 1996Pichon et al., 1992;Cardenas et al., 2000;Journet et al., 2001). Nod factor also induces mitotic activation of inner cortical cells that ultimately leads to the development of the nodule primordia. The formation of infection threads, that allow the invasion of bacteria into the root cortex, involves Nod factor, but also requires the presence of the rhizobial bacteria, suggesting the possible role of additional bacterial-signaling molecules (Dé-narié et al., 1996;Oldroyd, 2001).Genetic dissection of the Nod factor-signaling pathway has been limited by the availability of a genetically tractable legume system. Medicago truncatula and its symbiotic bacterial partner Sinorhizobium meliloti have been adopted as model organisms for the study of this symbiotic interaction (Cook, 1999). M. truncatula was selected as a model legume for its diploid genetics, relatively small genome, rapid life cycle, and ease of transformation. A number of studies in this species have identified genes critical for the establishment and regulation of the rhizobial sym...

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Section: Discussionmentioning

confidence: 73%

Section: Nodulin Gene Expression Is Greatly Reduced In Nsp2 Mutantsmentioning

confidence: 98%

“…Analysis of calcium spiking was performed as described by Ehrhardt et al (1996), with slight modifications as described by Wais et al (2000). Seedlings were grown overnight on BNM.…”

Section: Calcium-spiking Experimentsmentioning

confidence: 99%

mentioning

confidence: 99%

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Identification and Characterization of Nodulation-Signaling Pathway 2, a Gene of Medicago truncatula Involved in Nod Factor Signaling

2003

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“…DMI3 encodes a calcium and calmodulin dependent protein kinase (CCaMK) that is required to decipher the calcium oscillations triggered by the perception of the microsymbiont. 8,9 During rhizobial infection, DMI3 is expressed both in the epidermis and in the cortex shown that a construct combining DMI3 under the control of the epidermal and the cortical promoters, though functional since it provided a gain of function for nodule organogenesis, did not restore proper rhizobial infection. 1 Similarly, this construct did not restore arbuscule formation in the AM symbiosis and the AM infection phenotype was not different from that observed with the epidermal promoter alone.…”

Section: Resultsmentioning

confidence: 99%

Cell autonomous and non-cell autonomous control of rhizobial and mycorrhizal infection inMedicago truncatula

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Gough

et al. 2013

Plant Signaling & Behavior

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Root‐nodule Symbiosis: Molecular Basis of Nodule Formation

Oldroyd

2007

Encyclopedia of Life Sciences

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Nutrient availability is a major limitation to plant growth. Legumes have entered into a symbiotic interaction with nitrogen‐fixing rhizobial bacteria that provide the plant with a source of nitrogen. The legume/rhizobial symbiosis is globally important for introducing nitrogen into biological systems. Legume crops are used in sustainable agricultural processes to naturally enrich the soil for nitrogen. Our understanding of the molecular mechanisms that underlie this interaction is expanding and we are beginning to understand the means by which the molecular dialogue occurs between the plant and the bacteria. The signalling pathway in the plant, that is responsible for the recognition of the bacterial signal Nod factor, appears to have evolved in part from a pre‐existing signalling pathway necessary for the establishment of the mycorrhizal symbiosis. Further research in this field may help to apply this symbiosis more broadly in agriculture.

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Genetic analysis of calcium spiking responses in nodulation mutants of Medicago truncatula

Cited by 256 publications

References 41 publications

Identification and Characterization of Nodulation-Signaling Pathway 2, a Gene of Medicago truncatula Involved in Nod Factor Signaling

Identification and Characterization of Nodulation-Signaling Pathway 2, a Gene of Medicago truncatula Involved in Nod Factor Signaling

Cell autonomous and non-cell autonomous control of rhizobial and mycorrhizal infection inMedicago truncatula

Root‐nodule Symbiosis: Molecular Basis of Nodule Formation

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