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Receptor kinases of the Catharanthus roseus RLK1-like (CrRLK1L) family have emerged as important regulators of plant reproduction, growth and responses to the environment.sup.1. Endogenous RAPID ALKALINIZATION FACTOR (RALF) peptides.sup.2 have previously been proposed as ligands for several members of the CrRLK1L family.sup.1. However, the mechanistic basis of this perception is unknown. Here we report that RALF23 induces a complex between the CrRLK1L FERONIA (FER) and LORELEI (LRE)-LIKE GLYCOSYLPHOSPHATIDYLINOSITOL (GPI)-ANCHORED PROTEIN 1 (LLG1) to regulate immune signalling. Structural and biochemical data indicate that LLG1 (which is genetically important for RALF23 responses) and the related LLG2 directly bind RALF23 to nucleate the assembly of RALF23-LLG1-FER and RALF23-LLG2-FER heterocomplexes, respectively. A conserved N-terminal region of RALF23 is sufficient for the biochemical recognition of RALF23 by LLG1, LLG2 or LLG3, and binding assays suggest that other RALF peptides that share this conserved N-terminal region may be perceived by LLG proteins in a similar manner. Structural data also show that RALF23 recognition is governed by the conformationally flexible C-terminal sides of LLG1, LLG2 and LLG3. Our work reveals a mechanism of peptide perception in plants by GPI-anchored proteins that act together with a phylogenetically unrelated receptor kinase. This provides a molecular framework for understanding how diverse RALF peptides may regulate multiple processes, through perception by distinct heterocomplexes of CrRLK1L receptor kinases and GPI-anchored proteins of the LRE and LLG family. Uncovering a mechanism of peptide perception by the receptor kinase FER and the LLG1 protein in Arabidopsis thaliana suggests a role for diverse RALF peptides in regulating multiple growth and reproductive processes in plants., Author(s): Yu Xiao [sup.1] , Martin Stegmann [sup.2] [sup.3] , Zhifu Han [sup.1] , Thomas A. DeFalco [sup.2] [sup.4] , Katarzyna Parys [sup.5] , Li Xu [sup.1] , Youssef Belkhadir [...]

Synthesized oligonucleotides (oligos) can be used as effective probes similar to plasmid clones for chromosome identification in fluorescence in situ hybridization (FISH) analysis, making oligo FISH a simpler and more efficient molecular cytogenetic technique for studying plants. In this study, multiplex oligonucleotide probes, including pSc119.2-1, pAs1-4, [(GAA).sub.10], [(AAC).sub.6], and pTa71, were combined and used in FISH to identify chromosomes in common wheat, Thinopyrum intermedium, and a wheat--Th. intermedium amphiploid TE256-1. In comparison with general FISH probes, signals generated by the multiplex probes were more abundant, colorful, and characteristic. Combining the results of genomic in situ hybridization (GISH) with FISH, Th. intermedium chromosomes and alien chromosomes in TE256-1 could be classified and identified more precisely, especially the J- and [J.sup.s]-genome chromosomes. Moreover, based on the FISH results using multiplex probes, more structural variations inwheat chromosomesofTE256-1 were detected. The results indicated that multiplex oligo probes would haveawide rangeofapplication prospects in the creation and identification of wheat--Th. intermedium germplasms. Key words: Thinopyrum intermedium, in situ hybridization, multiplex probes, chromosome variation. Des oligonucléotides synthétisés (oligos) peuvent servir de sondes efficaces, tout comme des clones plasmidiques, pour l'identification de chromosomes en hybridation in situ en fluorescence (FISH). De tels oligos sont plus simples et efficaces pour réaliser l'analyse cytogénétique moléculaire chez les plantes. Dans ce travail, des sondes oligonucléotidiques en multiplexe, incluant le pSc119.2-1, pAs1-4, [(GAA).sub.10], [(AAC).sub.6] et pTa71, ont été employées conjointement pour des analyses FISH visant à identifier les chromosomes chez le blé tendre, le Thinopyrum intermedium et un ampiploïde blé--Th. intermedium (TE256-1). En comparaison aux sondes généralement employées, les signaux produits par les sondes multiplexes étaient plus abondants, colorés et distinctifs. En combinant les résultats d'analyses d'hybridation génomique in situ (GISH) et FISH, il était possible de classifier et d'identifier plus précisément les chromosomes du Th. intermedium (en soi et au sein de TE256-1), particulièrement ceux des génomes J et [J.sup.s]. De plus, sur la base des analyses FISH avec sondes en multiplexe, davantage de variations structurales chez les chromosomes du blé au sein de TE256-1 ont été détectées. Ces résultats indiquent que des sondes d'oligonucléotides en multiplexe offrent une plus grande gamme d'applications en vue de la création et de la caractérisation des ressources génétiques blé--Th. intermedium. [Traduit par la Rédaction] Mots-clés : Thinopyrum intermedium, hybridation in situ, sondes en multiplexe, variation chromosomique., Introduction Fluorescence in situ hybridization (FISH) is a common method for distinguishing and identifying chromosomes, analyzing chromosome constitution, and detecting chromosome variations in cytogenetic studies of wheat (Guo et al. [...]

Abstract: The objective of this study is to analyze patterns of genetic variation at genic expressed sequence tag--simple sequence repeats (EST-SSRs) andat chloroplast DNA markers inpopulations of American chestnut (Castanea [...]

Species of the red algal genus Mazzaella are widely distributed along the west coast of North America with 11 reported in British Columbia (BC). Like many red algal genera, however, accurate species identification is complicated by phenotypic plasticity and convergent evolution, and considerable taxonomic changes have taken place in recent years. To better understand the diversity of this genus in the BC flora, we variously compared COI-5P, rbcL, and ITS data for 407 collections predominantly from BC (n = 347) and California (n = 59) with other accessions in GenBank. We report the first records of Mazzaella phyllocarpa (Postels & Ruprecht) Perestenko in the BC flora whereas Mazzaella linearis (Setchell & N.L. Gardner) Fredericq is excluded--individuals previously assigned to this name referred to Mazzaella dewreedei sp. nov. Verified records and the distributional range for the poorly documented Mazzaella minima (G.J. Hollenberg) P.W. Gabrielson are greatly extended whereas northern records of Mazzaella rosea (Kylin) Fredericq are established. The presence of Mazzaella flaccida (Setchell & N.L. Gardner) Fredericq and Mazzaella japonica (Mikami) Hommersand (likely introduced) inBC are confirmed whereas resolution of the Mazzaella oregona (Doty) J.R. Hughey, P.C. Silva & Hommersand species complex necessitates description of Mazzaella macrocarpa sp. nov. Two additional cryptic complexes involving M. flaccida and M. oregona were discovered in the Californian flora, but are outside the scope of this study and are in need of further investigation. Key words: COI-5P, DNA barcode, Gigartinaceae, Mazzaella, rbcL. Les especes algacees rouges du genre Mazzaella sont largement distributes le long de la cote ouest de l'Amerique du Nord, dont 11 especes signalees en Colombie-Britannique (CB). Comme c'est le cas pour plusieurs genres d'algaces rouges, l'identification precise des especes est compliquee par la plasticite phenotypique et revolution convergente, et des changements taxonomiques considerables ont recemment eu lieu. Afin de mieux comprendre la diversite de ce genre dans la flore de la CB, nous avons compare la COI-5P, la rbcL et des donnees des ITS de 407 collections provenant de fa^on predominante de CB (n = 347) et de Californie (n = 59) a d'autres donnees de GenBank. Nous rapportons les premiers signalements de la presence de Mazzaella phyllocarpa (Postels & Ruprecht) Perestenko dans la flore de CB alors que Mazzaella linearis (Setchell & N.L. Gardner) Fredericq en est exclue--on refere maintenant a Mazzaella dewreedei sp. nov pour identifier les individus anterieurement designes par ce nom. Les signalements verifies et l'etendue de la distribution de l'espece pauvrement documentee Mazzaella minima (G.J. Hollenberg) P.W. Gabrielson sont grandement elargis alors que des signalements de Mazzaella rosea (Kylin) Fredericq sont etablis au nord. La presence de Mazzaella flaccida (Setchell & N.L. Gardner) Fredericq et de Mazzaella japonica (Mikami) Hommersand (probablement introduite) en CB est confirmee alors que la resolution des especes du complexe Mazzaella oregona (Doty) J.R. Hughey, P.C. Silva & Hommersand necessite la description de Mazzaella macrocarpa sp. nov. Deux complexes cryptiques additionnels qui impliquent M. flaccida et M. oregona ont ete decouverts dans la flore californienne, mais ils se trouvent hors des visees de cette etude et doivent etre etudies de maniere plus approfondie. [Traduit par la Redaction] Mots-cles: COI-5P, code-barres genetique, Gigartinaceae, Mazzaella, rbcL., Introduction The red algal family Gigartinaceae is generally accepted as having nine genera: Chondracanthus Kutzing, Chondrus Stackhouse, Gigartina Stackhouse, Iridaea Bory de Saint-Vincent, Mazzaella G. De Toni f., Ostiophyllum Kraft, [...]

Reverse transcription quantitative real-time polymerase chain reaction (PCR) is a widely used and reproducible method for studying gene expression changes. However, its accuracy and reliability is highly dependent on the normalization step. Cocos nucifera L., a perennial palm with a long productive life span, is frequently exposed to soil and atmospheric drought and other stresses. In applying gene expression analysis to understand coconut stress responses, validation of suitable reference genes is an important first step. In this study, seven putative reference genes were identified from coconut transcriptome data. The stability of these putative reference genes was assessed in a diverse set of 18 coconut samples subject to cold, drought, and high-salinity treatment and representing different endosperm developmental stages. Using statistical algorithms geNorm, NormFinder, and BestKeeper, eEF1-α and UBC10 genes were identified as stable reference genes in all stress treatments and endosperm development stages, consistent with validated reference genes in rice (Oryza saliva L.), potato (Solanum tuberosum L.), and other species. Further validation of analyzed reference genes by normalization of a C-repeat binding factor (CBF)- like gene in cold-treatment samples indicated that the less stable reference genes produced different results from the more stable reference genes, with weaker variation or higher expression levels of a target gene. Our results will be beneficial for further research on molecular mechanisms of stress resistance. Key words: Cocos nucifera, reference gene, abiotic stresses, normalization. On utilise frequemment la transcription inverse de la reaction de polymerase en chame en temps reel, constituant une methode reproductible pour l'etude des changements dans l'expression des genes. Cependant, sa precision et sa stabilite dependent etroitement de l'etape de normalisation. Le Cocos nucifera L., un palmier perenne a longue duree de vie reproductive, se voit frequemment expose a des secheresses de l'air et du sol et autres stress. En appliquant l'analyse de l'expression des genes pour comprendre la reaction du cocotier aux stress, la validation des genes de reference constitue une premiere etape importante. Les auteurs ont identifie sept genes de reference potentiels a partir des donnees transcriptomiques. Ils ont evalue la stabilite de ces genes de reference potentiels sur une diversite de 18 echantillons de cocotiers soumis a des traitements au froid, a la secheresse et a une forte salinite et a differents stades de developpement de l'endosperme. En utilisant les algorithmes geNorm, NormFinder et BestKeeper, ils ont identifie les genes eEF1-α et UBC10 comme genes de reference stables dans tous les traitements stressants et les stades du developpement de l'endosperme, ce qui est congru avec les genes de reference valides pour le riz (Oryza sativa L.), la pomme de terre (Solanum tuberosum L.) et autres especes. Une validation plus poussee des genes de reference analyses par la normalisation d'un gene de type CBF, chez des echantillons soumis au froid, indique que les genes de reference moins stables produisent differents resultats par rapport aux genes de reference plus stables, ainsi qu'une variation plus faible ou des degres d'expression plus eleves du gene cible. Les resultats serviront pour les recherches a venir sur les mecanismes moleculaires de la resistance aux stress. [Traduit par la Redaction] Mots-cles: Cocos nucifera, gene de reference, stress abiotiques, normalisation., Introduction Gene expression analyses are essential in all aspects of molecular biology research. Understanding gene expression patterns in different biological processes provides insight into complex regulatory networks (Dussert et al. [...]

The role of myeloblastosis (MYB) transcription factors in regulation of carbon flow among the various products of the phenylpropanoid pathway is still unclear. Carbon partitioning in Arabidopsis thaliana (L.) Heynh. was studied in a gain-of-function mutant (MYB75IPAP1-D) and a loss-of-function mutant (myb75-1). Determination of anthocyanins and total phenolics levels in leaf, peduncle, and root tissues of these mutants and their wild-type (WT) parental lines was assessed, as well as [sup.13]C partitioning between 'extractives' (predominantly cytoplasm) and 'nonextractives' (predominantly cell wall) of these tissues. The amounts of anthocyanins and phenolics in the leaves and peduncles of MYB75IPAP1-D mutant were higher than in its WT line. [sup.13]C excess in the extractives of leaves and peduncles of the mutant was also higher than that found in the WT line, indicating that the transcription factor MYB75 positively regulated carbon flow to flavonoids biosynthesis in the phenylpropanoid pathway. The myb75-1 mutant had higher distribution of [sup.13]C in both extractives and nonextractives of leaves and peduncles, especially in nonextractives of the peduncles, and lower levels of anthocyanins compared with its WT. This suggests that the knockout of MYB75 inhibits biosynthesis of anthocyanins and regulates carbon flow from cytoplasm to cell wall components by activating the biosynthesis of monolignols in cytoplasm, which, in turn, are transported and deposited to the secondary cell wall, resulting in secondary cell wall thickening. Patterns of anthocyanin level and [sup.13]C partitioning in roots were different from that seen in leaves and peduncles, suggesting that regulation of the phenylpropanoid pathway by MYB75 may be tissue specific. Key words: Arabidopsis, phenylpropanoid pathway, MYB75/PAP1-D, myb75-1, anthocyanin, lignin. On connait mal le role des facteurs de transcription de la myeloblastose (FTM) dans la regulation du flux de carbone impliquant divers produits du sentier des phenylpropanoides. Les auteurs ont etudie, sur l'Arabidopsis thaliana (L.) Heynh., la repartition du carbone chez un mutant gain-de-fonction (MYB75IPAP1-D) et un mutant perte-de-fonction (myb75-1). La determination des teneurs en anthocyanes et en phenols totaux dans les tissus foliaires, pedonculaires, et racinaires chez ces mutants et chez le type sauvage (TS) a ete evaluee, ainsi que la repartition du [sup.13]C entre les substances extractibles (surtout du cytoplasme) et nonextractibles (surtout des parois cellulaires) de ces tissus. On observe de plus fortes teneurs en anthocyanes et en phenols dans les feuilles et les pedoncules chez le mutant MYB75IPAP1-D que chez la lignee TS. Les exces de [sup.13]C dans les extractibles provenant des feuilles et des pedoncules du mutant sont egalement plus eleves que ceux de la lignee TS, ce qui indique que le facteur de transcription MYB75 regule positivement le flux de carbone vers la biosynthese des flavonoides dans le sentier phenylpropanoide. Quant au mutant myb75-1, il montre une plus forte distribution du [sup.13]C dans les deux groupes, extractibles et nonextractibles des feuilles et des pedoncules, surtout dans les nonextractibles des pedoncules, et des teneurs plus faibles en anthocyanes que les TS. Ceci suggere que l'extinction par le MYB75 inhibe la biosynthese des anthocyanes et regule le flux de carbone du cytoplasme vers les composantes parietales, en activant la biosynthese des monolignols dans le cytoplasme, lesquels a leur tour sont transportes et deposes dans la paroi secondaire de la cellule conduisant ainsi a un epaississement de la paroi secondaire. Les patrons de l'abondance des anthocyanes et la repartition du [sup.13]C dans les racines different de ce qui a ete vu dans les feuilles et leurs pedoncules, suggerant que la regulation du sentier des phenylpropanoides par le MYB75 serait specifique au tissu. [Traduit par la Redaction] Mots-cles: Arabidopsis, sentier des phenylpropanoides, MYB75/PAP1-D, myb75-1, anthocyane, lignine., Introduction The phenylpropanoid pathway is a multibranched system of reactions that coordinates with the shikimate and aromatic amino acid pathways to convert the carbon skeleton of L-phenylalanine into a wide [...]