Página 1 dos resultados de 92 itens digitais encontrados em 0.010 segundos

Identificação e caracterização de componentes da via de transdução de sinais do peptídeo hormonal RALF; Identification and characterization of components of the peptide hormone RALF signaling transduction pathway

Fiori, Celso Spada
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 05/10/2010 PT
Relevância na Pesquisa
36.06%
As pesquisas com os peptídeos hormonais de plantas se iniciaram na década de noventa com a descoberta da sistemina. Hoje existem diversos peptídeos identificados, e alguns deles já em avançado estágio de caracterização. O envolvimento desta classe de moléculas em diversas funções básicas e específicas da biologia dos vegetais despertou o interesse da comunidade científica. Dentre os peptídeos em fase de caracterização, destacam-se os representantes da família RALF. Os peptídeos RALF estão presentes em basicamente todo o reino vegetal, desde o musgo Physcomitrela pattens até as plantas superiores mono e dicotiledôneas. A conservação destes peptídeos no reino vegetal sugere um importante papel na fisiologia vegetal, e evidências recentes indicam a participação de RALF em processos básicos do desenvolvimento das plantas. O mecanismo pelo qual o peptídeo RALF atua e é percebido pela célula constitui etapa fundamental para sua caracterização funcional. Para tanto, no presente trabalho foram empregadas técnicas para identificação de proteínas de interação com RALF. Os resultados indicam que este peptídeo possivelmente tem sua atividade regulada pelo íon cálcio, através da interação com uma proteína de ligação a cálcio que...

Phage-Displayed Peptides as Developmental Agonists for Phytophthora capsici Zoospores

Bishop-Hurley, Sharon L.; Mounter, Sarah A.; Laskey, James; Morris, Roy O.; Elder, Jim; Roop, Philip; Rouse, Chris; Schmidt, Francis J.; English, James T.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /07/2002 EN
Relevância na Pesquisa
36.02%
As part of its pathogenic life cycle, Phytophthora capsici disperses to plants through a motile zoospore stage. Molecules on the zoospore surface are involved in reception of environmental signals that direct preinfection behavior. We developed a phage display protocol to identify peptides that bind to the surface molecules of P. capsici zoospores in vitro. The selected phage-displayed peptides contained an abundance of polar amino acids and proline but were otherwise not conserved. About half of the selected phage that were tested concomitantly induced zoospore encystment in the absence of other signaling agents. A display phage was shown to bind to the zoospore but not to the cyst form of P. capsici. Two free peptides corresponding to active phage were similarly able to induce encystment of zoospores, indicating that their ability to serve as signaling ligands did not depend on their exact molecular context. Isolation and subsequent expression of peptides that act on pathogens could allow the identification of receptor molecules on the zoospore surface, in addition to forming the basis for a novel plant disease resistance strategy.

Plant CLE peptides from two distinct functional classes synergistically induce division of vascular cells

Whitford, Ryan; Fernandez, Ana; De Groodt, Ruth; Ortega, Esther; Hilson, Pierre
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.1%
The Clavata3 (CLV3)/endosperm surrounding region (CLE) signaling peptides are encoded in large plant gene families. CLV3 and the other A-type CLE peptides promote cell differentiation in root and shoot apical meristems, whereas the B-type peptides (CLE41–CLE44) do not. Instead, CLE41 inhibits the differentiation of Zinnia elegans tracheary elements. To test whether CLE genes might code for antagonistic or synergistic functions, peptides from both types were combined through overexpression within or application onto Arabidopsis thaliana seedlings. The CLE41 peptide (CLE41p) promoted proliferation of vascular cells, although delaying differentiation into phloem and xylem cell lineages. Application of CLE41p or overexpression of CLE41 did not suppress the terminal differentiation of the root and shoot apices triggered by A-type CLE peptides. However, in combination, A-type peptides enhanced all of the phenotypes associated with CLE41 gain-of-function, leading to massive proliferation of vascular cells. This proliferation relied on auxin signaling because it was enhanced by exogenous application of a synthetic auxin, decreased by an auxin polar transport inhibitor, and abolished by a mutation in the Monopteros auxin response factor. These findings highlight that vascular patterning is a process controlled in time and space by different CLE peptides in conjunction with hormonal signaling.

Plant natriuretic peptides: Control of synthesis and systemic effects

Wang, Yu Hua; Donaldson, Lara; Gehring, Chris; Irving, Helen R
Fonte: Landes Bioscience Publicador: Landes Bioscience
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
45.88%
Plant natriuretic peptides (PNPs) are signaling molecules that are secreted into the apoplast particularly under conditions of biotic and abiotic stress. At the local level, PNPs modulate their own expression via feed forward and feedback loops to enable tuning of the response at the transcript and protein level and to prevent overexpression. PNPs also employ a systemic signal, possibly electrical, to rapidly alter photosynthesis and respiration not only in treated leaves but also in upper and lower leaves thereby modulating and integrating physiological responses at the level of the whole plant.

The Function of the CLE Peptides in Plant Development and Plant-Microbe Interactions

Betsuyaku, Shigeyuki; Sawa, Shinichiro; Yamada, Masashi
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: Artigo de Revista Científica
Publicado em 26/09/2011 EN
Relevância na Pesquisa
36.18%
The CLAVATA3 (CLV3)/ENDOSPERM SURROUNDING REGION (ESR) (CLE) peptides consist of 12 or 13 amino acids, including hydroxylated proline residues that may or may not contain sugar modifications, and function in a non-cell-autonomous fashion. The CLE gene was first reported in Zea mays (maize) as an endosperm-specific gene, ESR, in 1997 (Opsahl-Ferstad et al., 1997). CLE genes encode secreted peptides that function in the extracellular space as intercellular signaling molecules and bind to cellular surface receptor-like proteins to transmit a signal. CLE peptides regulate various physiological and developmental processes and its signaling pathway are conserved in diverse land plants. Recent CLE functional studies have pointed to their significance in regulating meristematic activity in plant meristems, through the CLE-receptor kinase-WOX signaling node. CLV3 and CLE40 are responsible for maintenance of shoot apical meristem (SAM) and root apical meristem (RAM) function, regulating homeodomain transcription factors, WUSCHEL (WUS) and WUSCHEL-related homeobox 5 (WOX5), respectively. CLE and WOX form an interconnected and self-correcting feedback loop to provide robustness to stem cell homeostasis. CLE peptides are required for certain plant-microbe interactions...

Small Signaling Peptides in Arabidopsis Development: How Cells Communicate Over a Short Distance

Murphy, Evan; Smith, Stephanie; De Smet, Ive
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
45.76%
To sustain plants’ postembryonic growth and development in a structure of cells fixed in cell walls, a tightly controlled short distance cell–cell communication is required. The focus on phytohormones, such as auxin, has historically overshadowed the importance of small peptide signals, but it is becoming clear that secreted peptide signals are important in cell–cell communication to coordinate and integrate cellular functions. However, of the more than 1000 potential secreted peptides, so far only very few have been functionally characterized or matched to a receptor. Here, we will describe our current knowledge on how small peptide signals can be identified, how they are modified and processed, which roles they play in Arabidopsis thaliana development, and through which receptors they act.

Linking ligand perception by PEPR pattern recognition receptors to cytosolic Ca2+ elevation and downstream immune signaling in plants

Ma, Yi; Walker, Robin K.; Zhao, Yichen; Berkowitz, Gerald A.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
36.1%
Little is known about molecular steps linking perception of pathogen invasion by cell surface sentry proteins acting as pattern recognition receptors (PRRs) to downstream cytosolic Ca2+ elevation, a critical step in plant immune signaling cascades. Some PRRs recognize molecules (such as flagellin) associated with microbial pathogens (pathogen-associated molecular patterns, PAMPs), whereas others bind endogenous plant compounds (damage-associated molecular patterns, DAMPs) such as peptides released from cells upon attack. This work focuses on the Arabidopsis DAMPs plant elicitor peptides (Peps) and their receptors, PEPR1 and PEPR2. Pep application causes in vivo cGMP generation and downstream signaling that is lost when the predicted PEPR receptor guanylyl cyclase (GC) active site is mutated. Pep-induced Ca2+ elevation is attributable to cGMP activation of a Ca2+ channel. Some differences were identified between Pep/PEPR signaling and the Ca2+-dependent immune signaling initiated by the flagellin peptide flg22 and its cognate receptor Flagellin-sensing 2 (FLS2). FLS2 signaling may have a greater requirement for intracellular Ca2+ stores and inositol phosphate signaling, whereas Pep/PEPR signaling requires extracellular Ca2+. Maximal FLS2 signaling requires a functional Pep/PEPR system. This dependence was evidenced as a requirement for functional PEPR receptors for maximal flg22-dependent Ca2+ elevation...

Transcriptional and Functional Classification of the GOLVEN/ROOT GROWTH FACTOR/CLE-Like Signaling Peptides Reveals Their Role in Lateral Root and Hair Formation1[W][OA]

Fernandez, Ana; Drozdzecki, Andrzej; Hoogewijs, Kurt; Nguyen, Anh; Beeckman, Tom; Madder, Annemieke; Hilson, Pierre
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
45.74%
Summary: The expression domains and phenotypes associated with distinct members of the GLV/RFG/CLEL secreted peptide family indicate that they function in multiple developmental programs, including meristem maintenance, gravitropism, lateral root emergence, and the formation of root hairs.

Plant elicitor peptides are conserved signals regulating direct and indirect antiherbivore defense

Huffaker, Alisa; Pearce, Gregory; Veyrat, Nathalie; Erb, Matthias; Turlings, Ted C. J.; Sartor, Ryan; Shen, Zhouxin; Briggs, Steven P.; Vaughan, Martha M.; Alborn, Hans T.; Teal, Peter E. A.; Schmelz, Eric A.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
45.98%
Insect-induced defenses occur in nearly all plants and are regulated by conserved signaling pathways. As the first described plant peptide signal, systemin regulates antiherbivore defenses in the Solanaceae, but in other plant families, peptides with analogous activity have remained elusive. In the current study, we demonstrate that a member of the maize (Zea mays) plant elicitor peptide (Pep) family, ZmPep3, regulates responses against herbivores. Consistent with being a signal, expression of the ZmPROPEP3 precursor gene is rapidly induced by Spodoptera exigua oral secretions. At concentrations starting at 5 pmol per leaf, ZmPep3 stimulates production of jasmonic acid, ethylene, and increased expression of genes encoding proteins associated with herbivory defense. These include proteinase inhibitors and biosynthetic enzymes for production of volatile terpenes and benzoxazinoids. In accordance with gene expression data, plants treated with ZmPep3 emit volatiles similar to those from plants subjected to herbivory. ZmPep3-treated plants also exhibit induced accumulation of the benzoxazinoid phytoalexin 2-hydroxy-4,7-dimethoxy-1,4-benzoxazin-3-one glucoside. Direct and indirect defenses induced by ZmPep3 contribute to resistance against S. exigua through significant reduction of larval growth and attraction of Cotesia marginiventris parasitoids. ZmPep3 activity is specific to Poaceous species; however...

The Alteration of Plant Morphology by Small Peptides Released from the Proteolytic Processing of the Bacterial Peptide TENGU1[W]

Sugawara, Kyoko; Honma, Youhei; Komatsu, Ken; Himeno, Misako; Oshima, Kenro; Namba, Shigetou
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
45.88%
A bacterial peptide effector undergoes proteolytic processing in plants and releases small peptides that alter plant morphology.

Regulation of Arabidopsis root development by small signaling peptides

Delay, Christina; Imin, Nijat; Djordjevic, Michael A.
Fonte: Frontiers Media S.A. Publicador: Frontiers Media S.A.
Tipo: Artigo de Revista Científica
Publicado em 06/09/2013 EN
Relevância na Pesquisa
56.1%
Plant root systems arise de novo from a single embryonic root. Complex and highly coordinated developmental networks are required to ensure the formation of lateral organs maximizes plant fitness. The Arabidopsis root is well-suited to dissection of regulatory and developmental networks due to its highly ordered, predictable structure. A myriad of regulatory signaling networks control the development of plant roots, from the classical hormones such as auxin and cytokinin to short-range positional signaling molecules that relay information between neighboring cells. Small signaling peptides are a growing class of regulatory molecules involved in many aspects of root development including meristem maintenance, the gravitropic response, lateral root development, and vascular formation. Here, recent findings on the roles of regulatory peptides in these aspects of root development are discussed.

Molecular Steps in the Immune Signaling Pathway Evoked by Plant Elicitor Peptides: Ca2+-Dependent Protein Kinases, Nitric Oxide, and Reactive Oxygen Species Are Downstream from the Early Ca2+ Signal1[OPEN]

Ma, Yi; Zhao, Yichen; Walker, Robin K.; Berkowitz, Gerald A.
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
66%
The immune signaling pathway evoked by endogenous plant elicitor peptides involves the brassinosteroid BAK1 coreceptor and a cGMP-dependent Ca2+ signal, as well as Ca2+-dependent protein kinases, NO, and ROS-dependent gene expression.

Maturation processes and structures of small secreted peptides in plants

Tabata, Ryo; Sawa, Shinichiro
Fonte: Frontiers Media S.A. Publicador: Frontiers Media S.A.
Tipo: Artigo de Revista Científica
Publicado em 04/07/2014 EN
Relevância na Pesquisa
36.05%
In the past decade, small secreted peptides have proven to be essential for various aspects of plant growth and development, including the maintenance of certain stem cell populations. Most small secreted peptides identified in plants to date are recognized by membrane-localized receptor kinases, the largest family of receptor proteins in the plant genome. This peptide-receptor interaction is essential for initiating intracellular signaling cascades. Small secreted peptides often undergo post-translational modifications and proteolytic processing to generate the mature peptides. Recent studies suggest that, in contrast to the situation in mammals, the proteolytic processing of plant peptides involves a number of complex steps. Furthermore, NMR-based structural analysis demonstrated that post-translational modifications induce the conformational changes needed for full activity. In this mini review, we summarize recent advances in our understanding of how small secreted peptides are modified and processed into biologically active peptides and describe the mature structures of small secreted peptides in plants.

Plant natriuretic peptides induce proteins diagnostic for an adaptive response to stress

Turek, Ilona; Marondedze, Claudius; Wheeler, Janet I.; Gehring, Chris; Irving, Helen R.
Fonte: Frontiers Media S.A. Publicador: Frontiers Media S.A.
Tipo: Artigo de Revista Científica
Publicado em 26/11/2014 EN
Relevância na Pesquisa
45.88%
In plants, structural and physiological evidence has suggested the presence of biologically active natriuretic peptides (PNPs). PNPs are secreted into the apoplast, are systemically mobile and elicit a range of responses signaling via cGMP. The PNP-dependent responses include tissue specific modifications of cation transport and changes in stomatal conductance and the photosynthetic rate. PNP also has a critical role in host defense responses. Surprisingly, PNP-homologs are produced by several plant pathogens during host colonization suppressing host defense responses. Here we show that a synthetic peptide representing the biologically active fragment of the Arabidopsis thaliana PNP (AtPNP-A) induces the production of reactive oxygen species in suspension-cultured A. thaliana (Col-0) cells. To identify proteins whose expression changes in an AtPNP-A dependent manner, we undertook a quantitative proteomic approach, employing tandem mass tag (TMT) labeling, to reveal temporal responses of suspension-cultured cells to 1 nM and 10 pM PNP at two different time-points post-treatment. Both concentrations yield a distinct differential proteome signature. Since only the higher (1 nM) concentration induces a ROS response, we conclude that the proteome response at the lower concentration reflects a ROS independent response. Furthermore...

Implication des peptides RALFs dans les communications cellulaires lors du développement du gamétophyte femelle chez Solanum chacoense et Arabidopsis thaliana.

Chevalier, Eric
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
FR
Relevância na Pesquisa
36.05%
Chez les angiospermes, la reproduction passe par la double fécondation. Le tube pollinique délivre deux cellules spermatiques au sein du gamétophyte femelle. Une cellule féconde la cellule œuf pour produire un zygote; l’autre féconde la cellule centrale pour produire l’endosperme. Pour assurer un succès reproductif, le développement du gamétophyte femelle au sein de l’ovule doit établir un patron cellulaire qui favorise les interactions avec le tube pollinique et les cellules spermatiques. Pour ce faire, un dialogue doit s’établir entre les différentes cellules de l’ovule lors de son développement, de même que lors de la fécondation. D’ailleurs, plusieurs types de communications intercellulaires sont supposées suite à la caractérisation de plusieurs mutants développementaux. De même, ces communications semblent persister au sein du zygote et de l’endosperme pour permettre la formation d’un embryon viable au sein de la graine. Malgré les développements récents qui ont permis de trouver des molécules de signalisation supportant les modèles d’interactions cellulaires avancés par la communauté scientifique, les voies de signalisation sont de loin très incomplètes. Dans le but de caractériser des gènes encodant des protéines de signalisation potentiellement impliqués dans la reproduction chez Solanum chacoense...

Plant CLE peptides from two distinct functional classes synergistically induce division of vascular cells

Whitford, R.; Fernandez, A.; De Groodt, R.; Ortega, E.; Hilson, P.
Fonte: Natl Acad Sciences Publicador: Natl Acad Sciences
Tipo: Artigo de Revista Científica
Publicado em //2008 EN
Relevância na Pesquisa
56.2%
The Clavata3 (CLV3)/endosperm surrounding region (CLE) signaling peptides are encoded in large plant gene families. CLV3 and the other A-type CLE peptides promote cell differentiation in root and shoot apical meristems, whereas the B-type peptides (CLE41–CLE44) do not. Instead, CLE41 inhibits the differentiation of Zinnia elegans tracheary elements. To test whether CLE genes might code for antagonistic or synergistic functions, peptides from both types were combined through overexpression within or application onto Arabidopsis thaliana seedlings. The CLE41 peptide (CLE41p) promoted proliferation of vascular cells, although delaying differentiation into phloem and xylem cell lineages. Application of CLE41p or overexpression of CLE41 did not suppress the terminal differentiation of the root and shoot apices triggered by A-type CLE peptides. However, in combination, A-type peptides enhanced all of the phenotypes associated with CLE41 gain-of-function, leading to massive proliferation of vascular cells. This proliferation relied on auxin signaling because it was enhanced by exogenous application of a synthetic auxin, decreased by an auxin polar transport inhibitor, and abolished by a mutation in the Monopteros auxin response factor. These findings highlight that vascular patterning is a process controlled in time and space by different CLE peptides in conjunction with hormonal signaling.; Ryan Whitford...

GOLVEN secretory peptides regulate auxin carrier turnover during plant gravitropic responses

Whitford, R.; Fernandez, A.; Tejos, R.; Perez, A.; Kleine-Vehn, J.; Vanneste, S.; Drozdzecki, A.; Leitner, J.; Abas, L.; Aerts, M.; Hoogewijs, K.; Baster, P.; De Groodt, R.; Lin, Y.C.; Storme, V.; Van de Peer, Y.; Beeckman, T.; Madder, A.; Devreese, B.; L
Fonte: Cell Press Publicador: Cell Press
Tipo: Artigo de Revista Científica
Publicado em //2012 EN
Relevância na Pesquisa
46.06%
Growth and development are coordinated by an array of intercellular communications. Known plant signaling molecules include phytohormones and hormone peptides. Although both classes can be implicated in the same developmental processes, little is known about the interplay between phytohormone action and peptide signaling within the cellular microenvironment. We show that genes coding for small secretory peptides, designated GOLVEN (GLV), modulate the distribution of the phytohormone auxin. The deregulation of the GLV function impairs the formation of auxin gradients and alters the reorientation of shoots and roots after a gravity stimulus. Specifically, the GLV signal modulates the trafficking dynamics of the auxin efflux carrier PIN-FORMED2 involved in root tropic responses and meristem organization. Our work links the local action of secretory peptides with phytohormone transport.; Ryan Whitford... et al.

Subcellular dynamics of the endogenous elicitor peptide AtPep1 and its receptors in Arabidopsis: implications for the plant immunity; Dinâmica subcelular do peptídeo endógeno AtPep1 e seus receptores em Arabidopsis: implicações na imunidade de plantas

Morea, Fausto Andres Ortiz
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 14/08/2015 EN
Relevância na Pesquisa
56.12%
This work investigated the subcellular dynamics of the plant elicitor peptide AtPep1 and its interplay with plant defense responses. First, an introduction of the plant innate immunity system is provided with emphasis on pattern trigger immunity (PTI), which is based on the recognition of "non-self" and "self" elicitor molecules by surface-localized patternrecognition receptors (PRRs). Then, the Arabidopsis endogenous peptides that act as selfelicitor molecules are presented, with details on AtPep1 and its PEPR receptors. Plant endomembrane trafficking is described, encompassing endocytic pathways, clathrin mediated endocytosis (CME) and receptor-mediated endocytosis (RME). In the next chapter, we explored strategies for the in vivo study of the subcellular behavior of AtPep1; to this end, we fused the precursor protein of AtPep1 (PROPEP1) to GFP and assessed its localization. We found that PROPEP1 was associated with the tonoplast and accumulated in the vacuole, suggesting that this organelle could work as the station where PROPEP1 is stored and later released, only in a danger situation, hence initiating AtPep1. Moreover, we generated AtPep1 versions labeled with fluorescent dyes and demonstrated that this peptide could be fluorescently tagged without loss of its biological activity. In chapter 3...

Regulation of Arabidopsis root development by small signaling peptides

Delay, Christina; Imin, Nijat; Djordjevic, Michael A.
Fonte: Frontiers Research Foundation Publicador: Frontiers Research Foundation
Tipo: Artigo de Revista Científica Formato: 6 pages
Relevância na Pesquisa
66.16%
Plant root systems arise de novo from a single embryonic root. Complex and highly coordinated developmental networks are required to ensure the formation of lateral organs maximizes plant fitness. The Arabidopsis root is well-suited to dissection of regulatory and developmental networks due to its highly ordered, predictable structure. A myriad of regulatory signaling networks control the development of plant roots, from the classical hormones such as auxin and cytokinin to short-range positional signaling molecules that relay information between neighboring cells. Small signaling peptides are a growing class of regulatory molecules involved in many aspects of root development including meristem maintenance, the gravitropic response, lateral root development, and vascular formation. Here, recent findings on the roles of regulatory peptides in these aspects of root development are discussed.; Christina Delay was supported by an Australia Postgraduate Award and GRDC Grains Industry Research Scholarship (GRS10329). This work was supported by an Australian Research Council grant to Michael A. Djordjeric and Nijat Imin (DP140103714).

CLE peptides control medicago truncatula nodulation locally and systemically

Mortier, V.; Den Herder, G.; Whitford, R.; Van de Velde, W.; Rombauts, S.; D'haeseleer, K.; Holsters, M.; Goormachtig, S.
Fonte: Amer Soc Plant Physiologists Publicador: Amer Soc Plant Physiologists
Tipo: Artigo de Revista Científica
Publicado em //2010 EN
Relevância na Pesquisa
46.1%
The CLAVATA3/embryo-surrounding region (CLE) peptides control the fine balance between proliferation and differentiation in plant development. We studied the role of CLE peptides during indeterminate nodule development and identified 25 MtCLE peptide genes in the Medicago truncatula genome, of which two genes, MtCLE12 and MtCLE13, had nodulation-related expression patterns that were linked to proliferation and differentiation. MtCLE13 expression was up-regulated early in nodule development. A high-to-low expression gradient radiated from the inner toward the outer cortical cell layers in a region defining the incipient nodule. At later stages, MtCLE12 and MtCLE13 were expressed in differentiating nodules and in the apical part of mature, elongated nodules. Functional analysis revealed a putative role for MtCLE12 and MtCLE13 in autoregulation of nodulation, a mechanism that controls the number of nodules and involves systemic signals mediated by a leucine-rich repeat receptor-like kinase, SUNN, which is active in the shoot. When MtCLE12 and MtCLE13 were ectopically expressed in transgenic roots, nodulation was abolished at the level of the nodulation factor signal transduction, and this inhibition involved long-distance signaling. In addition...