Expressed Sequence Tags from a Root-Hair-Enriched <i>Medicago truncatula</i> cDNA Library1

Covitz, Peter A.; Smith, Liane; Long, Sharon R.

doi:10.1104/pp.117.4.1325

Cited by 97 publications

(57 citation statements)

References 42 publications

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“…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%

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: 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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“…The concept of using cDNAs as a route to expedite gene discovery was first demonstrated in the early 1980s (Putney et al 1983). Later gene discovery in most plants was done primarily by sample sequencing of expressed sequence tags (ESTs) (Lim et al 1996;Covitz et al 1998).…”

Section: Introductionmentioning

confidence: 99%

Transcriptional profiling in pearl millet (Pennisetum glaucum L.R. Br.) for identification of differentially expressed drought responsive genes

Choudhary

Jayanand

Padaria

2015

Physiol Mol Biol Plants

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Pearl millet (Pennisetum glaucum) is an important cereal of traditional farming systems that has the natural ability to withstand various abiotic stresses. The present study aims at the identification and validation of major differentially expressed genes in response to drought stress in P. glaucum by Suppression Subtractive Hybridization (SSH) analysis. Twenty-two days old seedlings of P. glaucum cultivar PPMI741 were subjected to drought stress by treatment of 30 % Polyethylene glycol for different time periods 30 min

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“…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 number of genes showing enhanced expression in plant-rhizobium symbiosis were identified Gyö rgyey et al, 2000).…”

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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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Expressed Sequence Tags from a Root-Hair-Enriched Medicago truncatula cDNA Library1

Cited by 97 publications

References 42 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

Transcriptional profiling in pearl millet (Pennisetum glaucum L.R. Br.) for identification of differentially expressed drought responsive genes

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

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