Calcium Spiking in Plant Root Hairs Responding to Rhizobium Nodulation Signals

Ehrhardt, David; Wais, Rebecca J.; Long, Sharon R.

doi:10.1016/s0092-8674(00)81234-9

Cited by 597 publications

(515 citation statements)

References 40 publications

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“…Indeed there is evidence that other plant cell types have the potential to encode information in the calcium signal. Temporal oscillations in [Ca 2+ ] cyt (Ehrhardt et al 1996) and spatial gradients and`waves' of [Ca 2+ ] cyt (Franklin-Tong et al 1997) have been observed in root hairs and pollen tubes. Studies of the mechanisms of encoding speci¢city are perhaps further advanced in guard cells not because of any special intrinsic property but because guard cells have been the subject of intensive investigation.…”

Section: Discussionmentioning

confidence: 99%

The control of specificity in guard cell signal transduction

Hetherington¹,

Gray

Leckie

et al. 1998

Phil. Trans. R. Soc. Lond. B

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Stomatal guard cells have proven to be an attractive system for dissecting the mechanisms of stimulusr esponse coupling in plants. In this review we focus on the intracellular signal transduction pathways by which extracellular signals bring about closure and opening of the stomatal pore. It is proposed that guard cell signal transduction pathways may be organized into functional arrays or signalling cassettes that contain elements common to a number of converging signalling pathways. The purpose of these signalling cassettes may be to funnel extracellular signals down onto the ion transporters that control the £uxes of ions that underlie stomatal movements. Evidence is emerging that speci¢city in guard cell signalling may be, in part, encoded in complex spatio-temporal patterns of increases in the concentration of cytosolic-free calcium ([Ca 2+ ] cyt ). It is suggested that oscillations in [Ca 2+ ] cyt may generate calcium signatures that encode information concerning the stimulus type and strength. New evidence is presented that suggests that these calcium signatures may integrate information when many stimuli are present.

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Section: Discussionmentioning

confidence: 99%

The control of specificity in guard cell signal transduction

Hetherington¹,

Gray

Leckie

et al. 1998

Phil. Trans. R. Soc. Lond. B

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“…Calcium Spiking Is Induced in nsp2-2 M. truncatula root hair cells respond rapidly to Nod factor by undergoing cytosolic calcium oscillations, termed calcium spiking (Ehrhardt et al, 1996). 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).…”

Section: Nodulin Gene Expression Is Greatly Reduced In Nsp2 Mutantsmentioning

confidence: 99%

“…This bacterial suspension was diluted 1/50 in 10 mm MgSO 4 and inoculated onto plants by flooding the roots with the inoculum. Nod factor preparations were isolated as described by Ehrhardt et al, 1996.…”

Section: Plant Growth Conditions and Bacterial Strainsmentioning

confidence: 99%

“…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%

“…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.…”

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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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Oligosaccharide signaling of plant cells

Etzler

1998

J. Cell. Biochem.

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A variety of oligosaccharide signals have been identified that function in the regulation of plant development, defense, and other interactions of plants with the environment. Some of these oligosaccharides are produced by various pathogens or symbionts, whereas others are synthesized by the plant itself. This mini-review summarizes our present state of information on these oligosaccharide signals and provides an overview of approaches being used to identify receptors for these signals and gain an understanding of the mechanism(s) by which these signals activate downstream events. Possible biotechnological applications of future work in this field are also considered. J. Cell. Biochem. Suppls. 30/31:123-128, 1998. © 1998 Wiley-Liss, Inc.

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Calcium Spiking in Plant Root Hairs Responding to Rhizobium Nodulation Signals

Cited by 597 publications

References 40 publications

The control of specificity in guard cell signal transduction

The control of specificity in guard cell signal transduction

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

Oligosaccharide signaling of plant cells

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