Regulation and Identity of Florigen: Flowering Locus T Moves Center Stage

The transition from vegetative to reproductive growth is controlled by day length in many plant species. Day length is perceived in leaves and induces a systemic signal, called florigen, that moves through the phloem to the shoot apex. At the shoot apical meristem (SAM), florigen causes changes in gene expression that reprogram the SAM to form flowers instead of leaves. Analysis of flowering of Arabidopsis thaliana placed the CONSTANS/FLOWERING LOCUS T (CO/FT) module at the core of a pathway that promotes flowering in response to changes in day length. We describe progress in defining the molecular mechanisms that activate this module in response to changing day length and the increasing evidence that FT protein is a major component of florigen. Finally, we discuss conservation of FT function in other species and how variation in its regulation could generate different flowering behaviors

The SBP-Box Gene SPL8 Affects Reproductive Development and Gibberellin Response in Arabidopsis

Plant development requires a precise and dynamic regulatory network, in which transcription factors play major roles by temporally and spatially regulating gene expression. The SBP-box genes encode a group of plant-specific transcription factors, highly conserved in their DNA-binding domain, but quite heterogeneous outside. Gain- or loss-of-function of several SBP-box genes, including Maize LIGULELESS1 and Teosinte glume architecture1, Arabidopsis SPL3, SPL8, and SPL14, display diverse developmental defects, indicating that they function in different developmental processes. The work presented in this thesis aimed to uncover the role of the Arabidopsis SBP-box gene SPL8 in plant development and to integrate its function in an existing regulatory network. This has been achieved through the application of molecular genetic, biochemical and microscopic techniques. As deduced from its semi-sterile loss-of-function phenotype, previous studies have shown that SPL8 affects reproductive development. Remarkably, and extensively described in this thesis, SPL8 gain-of-function also caused sterility. However, unlike the loss-of-function mutant in which anther development is defective at early stage of sporogenesis, gain-of-function affects fertility through the non-dehiscence of anthers. Furthermore, constitutive SPL8 expression resulted in a pleiotropic phenotype partly resembling gibberellin-deficient mutants. Although some phenotypical changes could be rescued by exogenous GAs, seed germination, root elongation and fertility could not. Molecular data indicated that genes involved in GA biosynthesis/response are affected in SPL8 overexpressing lines, suggesting altered endogenous GA levels. Because SPL8 is assumed to encode a transcription factor, its nuclear targeting has also been briefly explored using GFP fusion constructs. Within the SBP-domain, a highly conserved serine residue has been predicted to be a target for phosphorylation. Mutation of this serine residue had a great impact on the subcellular localization of SPL8, suggesting the involvement of post-transcriptional regulation in its function. To obtain additional information on the regulatory network, SPL8 might be integrated in, a yeast two-hybrid screen was performed. Many putative SPL8 interacting proteins could be identified. The functions of most of these are unknown or predicted to be involved in general cellular activities and therefore not very helpful to clear the function of SPL8. For two putative interactors, selected on the basis of their role in gene regulation and expression pattern, respective mutant plants could be obtained. However, the absence of obvious mutant phenotypes allowed no further conclusions concerning the relevance of their interaction with SPL8. The experiments in this thesis investigated the role of SPL8 in plant development. Taken the results together, it could be proposed that SPL8 acts as a local regulator in a subset of GA-mediated developmental processes, positively in anther development, but negatively in seed germination and root elongation. Further studies, aiming at the identification of target genes and genetic interactions with other GA-signaling components, are needed to deepen our understanding of the role SPL8 plays in these more defined aspects of plant development

Advances in Laser Materials Processing

Laser processing has become more relevant today due to its fast adaptation to the most critical technological tasks, its ability to provide processing in the most rarefied and aggressive mediums (vacuum conditions), its wide field of potential applications, and the green aspects related to the absence of industrial cutting chips and dust. With the development of 3D production, laser processing has received renewed interest associated with its ability to achieve pointed to high-precision powder melting or sintering. New technologies and equipment, which improve and modify optical laser parameters, contribute to better absorption of laser energy by metals or powder surfaces and allow for multiplying laser power that can positively influence the industrial spread of the laser in mass production and advance the existing manufacturing methods. The latest achievements in laser processing have become a relevant topic in the most authoritative scientific journals and conferences in the last half-century. Advances in laser processing have received multiple awards in the most prestigious competitions and exhibitions worldwide and at international scientific events. The Special Issue is devoted to the most recent achievements in the laser processing of various materials, such as cast irons, tool steels, high entropy alloys, hard-to-remelt materials, cement mortars, and post-processing and innovative manufacturing based on a laser

The molecular mechanisms of vernalization induced flowering in temperate cereals

Plants coordinate development with environmental cues to ensure flowering occurs under optimal seasonal conditions. Many plants from temperate regions only flower after exposure to prolonged cold: vernalization. While the molecular mechanisms of the vernalization response have been studied extensively in the model plant Arabidopsis, this seasonal flowering response has probably evolved independently in other plants. For instance, no homologues of FLOWER LOCUS C (FLC), the gene central to the vernalization response in Arabidopsis, have been found in economically important crops such as barley and wheat. Instead VERNALIZATION1 (VRN1) is central to the vernalization response in these plants. This highlights a need to study the vernalization response directly in cereal crop species. Previous studies have identified VRN1 as a master regulator of the vernalization response in cereals, but the extent to which other genes contribute is unclear. To identify genes that are potentially involved in regulating the vernalization response the Barley1 Affymetrix chip was used to compare gene expression in barley seedlings during short or prolonged cold treatments. Additionally, gene expression was assayed when plants were shifted to normal growth temperatures following prolonged cold treatment. This identified genes that show lasting changes in transcriptional activity, which might contribute to vernalization-induced flowering. Only a small group of genes showed a lasting change in activity when plants were shifted to warm conditions following prolonged cold. These included VRN1 and another MADS box gene, ODDSOC2 (OS2). OS2 belongs to a group of MADS box genes only found in grasses. Expression analysis showed that OS2 is down-regulated by cold and that long term repression of OS2 is dependent on VRN1. Overexpression of OS2 in barley delayed flowering and caused dwarfing. These phenotypes could be due to the down-regulation of FLOWERING PROMOTING FACTOR1 (FPF1)-like genes. In Arabidopsis FPF1 promotes flowering and elongation. Thus down-regulation of OS2 likely contributes to the acceleration of flowering through the de-repression of FPF1-like genes as daylength increases in spring. To determine if any components of the vernalization response pathway are conserved between Arabidopsis and temperate cereals, barley homologues of the Arabidopsis MADS box gene SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (SOC1) were identified and characterised. In Arabidopsis SOC1 promotes flowering and is positively regulated by vernalization, long-days, and development. Similar to SOC1, the expression of a barley SOC1-like genes increases during development. Unlike Arabidopsis, the expression of a barley SOC1-like gene, HvSOC1-like1 was similar regardless of daylength suggesting that photoperiod does not regulate the expression of these genes. The regulation of HvSOC1-like genes by vernalization is also different. The expression of HvSOC1-like genes was lower in the leaves and crown tissue of vernalized plants versus non-vernalized plants. Over-expression of one of the barley SOC1-like genes, HvSOC1-like1, delayed flowering and caused dwarfing in barley plants. The phenotypes of these plants are different SOC1-like genes. Overall these data suggest that cereal SOC1-like genes have evolved differently and have different regulatory functions than SOC1 from Arabidopsis. Overall the findings from this thesis extend our understanding of the vernalization response in temperate cereals and highlight the difference of how this seasonal flowering response is regulated in temperate cereals and Arabidopsis. Since VRN1 is one of only a limited number of genes that initiates flowering in temperate cereals, understanding how VRN1 is regulated and identifying the targets of VRN1 will be of critical importance to understanding the mechanisms of seasonal flowering responses in these plants

Bar ‘Ebroyo's ecclesiastical history : church history writing in the 13th century Middle East

L'Histoire Ecclésiastique de Grégoire Bar ‘Ebroyo (1225/6-1286 apr. J.-C.), auteur syro-orthodoxe et maphrien de l’Est, a depuis longtemps été reconnue comme une source historique inestimable pour l’histoire de l’Antiquité tardive et médiévale du Moyen-Orient, mais elle a reçu une attention limitée du monde scientifique en tant qu’œuvre de littérature à part entière, et n’a jamais fait l’objet d’une monographie. En outre, l’Histoire Ecclésiastique n’est encore et toujours seulement accessible que par l’intermédiaire d’une édition du 19e s., qui est simplement une reproduction diplomatique d’un manuscrit du 16e s. Bien que la Chronique de Bar ‘Ebroyo, dont l’Histoire Ecclésiastique forme la seconde partie, soit le seul ouvrage historiographique en syriaque préservé dans plus d’un seul manuscrit, sa riche tradition manuscrite n’a jamais été examinée. Le but de cette thèse doctorale est tout d’abord de fournir une étude philologique et historiographique de l’Histoire Ecclésiastique. Plus particulièrement, je propose une analyse de a) la tradition manuscrite et de la transmission du texte, b) de la relation avec la tradition du genre de l’histoire ecclésiastique, c) l’étude des sources. Cette étude s’accompagne d’une nouvelle édition de texte et d’une traduction anglaise.The Ecclesiastical History of Gregory Bar ‘Ebroyo (1225/6-1286 A.D.), Syrian Orthodox author and maphrian of the East, has long been recognized as an invaluable historical source for the history of the Late Antique and Medieval Middle East but it has received limited scholarly attention as a work of literature in its own right, and it has never been made the object of a book-length study. Moreover, the Ecclesiastical History is still available only via a 19th century edition, which is basically a diplomatic reproduction of a 16th century manuscript. Although Bar ‘Ebroyo’s Chronicle, of which the Ecclesiastical History forms the second part, is the only Syriac historiographical work preserved in more than one manuscript, its rich manuscript tradition has never been examined. The purpose of this thesis is to provide a first philological and historiographical study of the Ecclesiastical History. More particularly, I propose an analysis of a) the manuscript tradition and the transmission of the text, b) the relation with the tradition of the genre Ecclesiastical History, c) the study of the sources. This study is accompanied by a newly established text and an English translation

Latin and Arabic

As linguistic systems comprising a large variety of written and oral registers including derivate “languages” and “dialects,” Latin and Arabic have been of paramount importance for the history of the Euromediterranean since Antiquity. Moreover, due to their long-term function as languages of administration, intellectual activity, and religion, they are often regarded as cultural markers of Europe and the (Arabic-)Islamic sphere respectively. This volume explores the many dimensions and ramifications of Latin-Arabic entanglement both from macro-historical as well as from micro-historical perspectives. Visions of history marked by the binary opposition of “Islam” and “the West” tend to ignore these important facets of Euromediterranean entanglement, as do historical studies that explain complex transcultural processes without giving attention to their linguistic dimension.Latein und Arabisch haben als Sprachsysteme mit einer großen Vielfalt an schriftlichen und mündlichen Registern, darunter “Sprachen” und Dialekte”, in der Geschichte des Euromediterraneums seit der Antike eine herausragende Rolle gespielt. Aufgrund ihrer lang anhaltenden Funktion als Sprachen der Administration, intellektueller Aktivität und Religion, werden sie oft als kultureller Marker Europas und der arabisch-islamischen Sphäre betrachtet. Dieser Band untersucht die vielen Facetten lateinisch-arabischer Verflechtung aus makro- und mikrohistorischer Perspektive. Er stellt die binäre Opposition von “Islam” und “dem Westen” in Frage und hebt die sprachliche Dimension christlich-muslimischer Beziehungen hervor

Latin and Arabic

As linguistic systems comprising a large variety of written and oral registers including derivate “languages” and “dialects,” Latin and Arabic have been of paramount importance for the history of the Euromediterranean since Antiquity. Moreover, due to their long-term function as languages of administration, intellectual activity, and religion, they are often regarded as cultural markers of Europe and the (Arabic-)Islamic sphere respectively. This volume explores the many dimensions and ramifications of Latin-Arabic entanglement both from macro-historical as well as from micro-historical perspectives. Visions of history marked by the binary opposition of “Islam” and “the West” tend to ignore these important facets of Euromediterranean entanglement, as do historical studies that explain complex transcultural processes without giving attention to their linguistic dimension

Genetic and physiological analysis of juvenility in plants

One of the distinguishable plant developmental events is the transition from the vegetative to reproductive phase (RP) of development. This stage is preceded by the juvenile to adult transition within the vegetative phase. During the juvenile vegetative phase (JVP) plants are incompetent to initiate reproductive development and are effectively insensitive to photoperiod. With the change to the adult vegetative phase (AVP), plants attain competence to respond to floral inducers, which is required for the transition to the RP. This study exploits Antirrhinum and Arabidopsis as model systems to understand the genetic and environmental factors that regulate floral incompetence during the JVP. Determinants such as irradiance and [CO2] were found to be key modifiers of the JVP. A relationship between photosynthetic assimilate levels and vegetative phase transition was revealed by analysis of carbohydrates in plants at defined developmental stages. Experimental data suggest that carbohydrate levels may be required to reach a specific threshold before plants undergo the transition from a juvenile to an adult phase of vegetative growth. This may be necessary in order to sustain a steady supply of sugars for sufficient bulk flow from the leaves to the shoot apical meristem (SAM), via the phloem, to enable delivery of florigen, which thus renders the SAM competent to flower. Determination of the JVP in Arabidopsis mutants impaired in different genetic pathways has shown that multiple inputs influence the timing of the vegetative phase transition. Carbohydrates have been demonstrated to be involved possibly through their function as nutrients or signals or by their interaction with hormones. Physiological analysis of flowering time mutants has shown that a variety of signals act to promote and enable the juvenile to adult phase transition that involves both floral activators and repressors