Transient Induction of a Peroxidase Gene in Medicago truncatula Precedes Infection by Rhizobium meliloti

Cook, Douglas R.; Dreyer, Dale; Bron, Dominique; Howell, Mary; Nony, Emmanuel; VandenBosch, Kathryn A.

doi:10.2307/3869836

Cited by 71 publications

(111 citation statements)

References 34 publications

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“…We chose to examine the expression of two such genes RIP1 and ENOD11, as representatives of early nodulin genes (Cook et al, 1995;Journet et al, 2001). We assessed RIP1 expression using northern analysis.…”

Section: Nodulin Gene Expression Is Greatly Reduced In Nsp2 Mutantsmentioning

confidence: 99%

“…RNA samples were separated on a 12 g L Ϫ1 agarose gel containing 62 mL L Ϫ1 formaldehyde. The RNA was transferred to a nylon membrane (Hybond N, Amersham Biosciences UK, Ltd, Little Chalfont, Buckinghamshire, UK) and hybridized with a 280-bp fragment from exon 2 of RIP1 (Cook, Dreyer et al, 1995) and secondarily with a 720-bp fragment that represents a full-length cDNA clone of an actin homolog identified from the M. truncatula expressed sequence tag database (Covitz et al, 1998).…”

Section: Rna Gel-blot Analysismentioning

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: Nodulin Gene Expression Is Greatly Reduced In Nsp2 Mutantsmentioning

confidence: 99%

Section: Rna Gel-blot Analysismentioning

confidence: 99%

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

2003

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“…Within several hours these changes are followed by root hair deformation (Heidstra et al, 1994), cortical cell dedifferentiation and mitosis (Spaink et al, 1991;Truchet et al, 1991;Relic et al, 1993), and the expression of genes such as ENOD12 (Bauer et al, 1994;Journet et al, 1994) and rip1 (Cook et al, 1995) in the differentiating root epidermis. These findings have implied the existence of Nod factor receptors on the roots of the plant and the presence of a signal transduction mechanism.…”

mentioning

confidence: 99%

Localization of a Nod Factor-Binding Protein in Legume Roots and Factors Influencing Its Distribution and Expression

Kalsi

Etzler

2000

Plant Physiology

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The roots of the legume Dolichos biflorus contain a lectin/nucleotide phosphohydrolase (Db-LNP) that binds to the Nod factor signals produced by rhizobia that nodulate this plant. In this study we show that Db-LNP is differentially distributed along the surface of the root axis in a pattern that correlates with the zone of nodulation of the root. Db-LNP is present on the surface of young and emerging root hairs and redistributes to the tips of the root hairs in response to treatment of the roots with a rhizobial symbiont or with a carbohydrate ligand. This redistribution does not occur in response to a non-symbiotic rhizobial strain or a root pathogen. Db-LNP is also present in the root pericycle where its level decreases upon initiation of nodule formation. Maximum levels of Db-LNP are found in 2-d-old roots, and the expression of this root protein is increased when the plants are grown in the absence of NO 3 Ϫ and NH 4 ϩ . These results support the possibility that Db-LNP is involved in the initiation of the Rhizobium legume symbiosis.

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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).…”

mentioning

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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Transient Induction of a Peroxidase Gene in Medicago truncatula Precedes Infection by Rhizobium meliloti

Cited by 71 publications

References 34 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

Localization of a Nod Factor-Binding Protein in Legume Roots and Factors Influencing Its Distribution and Expression

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

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