<p> Experiments described in this study were carried out 1n order to (a) extend previous studies on the analysis of the response to 5-aminoura.cil to small primordia and primary roots of Vicia faba and (b) to determine whether treatment with deoxynucleos1des would alter the cell's response to 5-aminouracil , either in DNA synthesis or at the S -G2 transition block. </p> <p> The present study reveals that the population heterogeneity, which was found to exist in lateral roots, just emerged roots, very large primordia, and large primordia, is also present in primary roots and small primordia: also, that the ratio of fast cycling cells to slow cycling cells remains constant throughout root development. </p> <p> All root meristems of V. faba exhibited the same general pattern of recovery after exposure to 5-aminouracil, i.e. the initial drop in mitotic index was followed by an increase to a value above controls. Variations between the different developmental stages were seen in (a) the time of onset of recovery, (b) the time of the appearance of the peak of mitoses, and (c) the degree of synchronization of recovery. </p> <p> Data from post-5-aminouracil nucleoside treatments revealed that the nucleosides were unable to produce a reversal of the 5-aminouracil-induced block at the S -G2 transition, but were able to increase the rate of DNA synthesis and thus alter one of the effects of 5-aminouracil on cell cycle kinetics. </p> / Thesis / Master of Science (MSc)

Le déterminisme de la formation de la grappe reste parmi les phénomènes les moins bien précisés de la physiologie de la Vigne. La question a été abordée de plusieurs façons mais les éléments de réponse obtenus ne permettent pas encore de se faire une idée synthétique des mécanismes fondamentaux qui produisent l’apparition des primordia inflorescentiels (PI) en année N-1 et qui pourraient régir jusqu’à 65 à 70% du rendement final en année N. Notre étude s’est donc focalisée sur (i) la caractérisation du processus de formation des PI dans les bourgeons latents de vigne (Vitis vinifera L. Merlot) et la redéfinition de la constitution du rendement, (ii) la compréhension des mécanismes d’initiation et de différenciation des PI et (iii) l’évaluation des impacts de différents facteurs (ABA exogène, lumière et effeuillage) sur ces mécanismes.Cette étude intégrale combinant des approches multi-échelles et multi-disciplinaires a permis dans un premier temps de mettre en évidence le déterminisme de la phase d’induction inflorescentielle dans la construction du rendement en identifiant trois phases clés du processus de formation des PI et en y intégrant une nouvelle notion qu’est le « degré de ramification des PI » ; puis dans un second temps, de proposer certains modes de régulation des mécanismes d’initiation et de différenciation des PI en identifiant trois types de marqueurs précoces de la fertilité potentielle : des marqueurs moléculaires (VvCLE25-1, VvTFL1a et VvMFT1), biochimiques (équilibre CKs/AIA, D-glucose et amidon), et environnementaux (ensoleillement et température journaliers cumulés). L’ensemble des résultats pourra contribuer au développement d’un outil prédictif précoce de la « fertilité potentielle » (et donc du rendement probable maximum) afin de mieux guider et gérer la taille et les pratiques culturales. / The grape cluster formation determinism remains the one of the undefined phenomena in grapevine physiology process. The topic has been tackled in multiple ways. However, based on all the known information, we still are not allowed to get a synthetic idea of the fundamental mechanisms that produce the appearance of inflorescential primordia in year N-1 and which could govern up to 65 to 70 % of final yield in year N. Our study focuses thus on (i) the characterization of IP formation process in grapevine latent buds (Vitis vinifera L. Merlot) and the redefinition of yield constitution, (ii) understanding IP initiation and differentiation mechanisms, and (iii) evaluating the impacts of different factors (exogenous ABA, light and leaf removal) on these mechanisms.This comprehensive study, which combines multi-scale and multi-disciplinary approaches, firstly allowed us to highlight the determinism of inflorescence induction phase in yield construction by identifying three key phases in IP formation process and by incorporating a new notion which is "IP branching degree". Secondly, it proposed certain modes of regulation of IP initiation and differentiation mechanisms by identifying three types of early markers of bud fruitfulness: molecular markers (VvCLE25-1, VvTFL1a and VvMFT1), biochemical markers (CKs/IAA balance, D-glucose and starch), and environmental markers (cumulative daily sunshine and temperature).The all-inclusive results contribute to the development of an early predictive tool of "bud fruitfulness" (and thereby the probable maximum yield) to better guide and manage the grapevine training and other cultural practices.

Les insectes présentent une étonnante diversité morphologique dans les organes de vol, et cette évolution a conduit à leur rayonnement au sein du règne animal. L'une des modifications les plus frappantes est la transformation des ailes postérieures en structures d'équilibrage très réduites, appelées haltères. Des travaux pionniers chez la drosophile ont montré que la spécification des haltères est sous le contrôle du gène Hox Ultrabithorax (Ubx). En revanche, la formation des ailes antérieures est décrite pour être indépendante des gènes Hox, mais cette observation est controversée chez d’autres insectes. Au cours de mon doctorat, j'ai réexaminé le rôle des gènes Hox pour la spécification des organes du vol chez la drosophile. Mes travaux montrent que la protéine Hox Antennapedia (Antp) est exprimée à un niveau faible dans des cellules spécifiques du primordium de la marge et est nécessaire à la formation correcte de l’aile adulte. De manière étonnante, Antp peut également fonctionner comme Ubx et former un haltère quand la protéine est exprimée à des niveaux similaires à ceux de Ubx. Ainsi, la formation d’organes de vol divergents chez la drosophile est directement contrôlée par une dose spécifique de protéine Hox et non par une protéine Hox spécifique. Les gènes Hox sont intrinsèquement liés à l'évolution de la diversité morphologique chez les animaux. Par conséquent, le rôle de la dose des protéines Hox a également été testé d'un point de vue évolutif parmi plusieurs lignages d'insectes. Les résultats montrent que la dose de protéines Hox est à peu près la même entre les primordia antérieur et postérieur d’un insecte à quatre ailes comme Bombyx mori. Dans l’ensemble, mes résultats démontrent que la spécification des organes de vol n’est pas un programme Hox-indépendant et que la variation de la dose des protéines Hox est un moyen de modifier la taille et la forme de l’aile, pouvant ultimement aboutir à la création d’un tout nouvel organe d’équilibrage au cours de l’évolution des insectes. Enfin, au cours de mon doctorat, j'ai également participé à plusieurs projets parallèles visant à identifier et à caractériser le rôle des nouveaux cofacteurs des protéines Hox dans différents contextes développementaux, notamment la spécification de l’haltère et la répression de l'autophagie. Ces travaux s'appuient en partie sur la complémentation de fluorescence bimoléculaire (BiFC), une méthode que nous avons récemment couplée à la panoplie d'outils génétiques de la drosophile pour réaliser des criblages d'interactions protéine-protéine à grande échelle in vivo. / Insects display an astonishing array of diversity in flight appendage morphologies and theirevolution led to the catalyzed radiation of insects in the animal kingdom. The first definite modellinking the Hox genes to morphological evolution was demonstrated in Drosophila. One of themost striking modifications is the transformation of hindwings into highly reduced balancingstructures called halteres. Work in Drosophila established that the specification of halteres isunder the control of a single Hox gene, Ultrabithorax (Ubx). In contrast, the formation of forewingshas been described to be Hox-independent. During my Ph.D., I reconsidered the role of Hox genesfor flight appendage specification in Drosophila. I show that the Hox protein Antennapedia (Antp)is expressed at a low level in specific cells of the wing blade primordium and required for theproper formation of the adult wing. Moreover, Antp works like Ubx to form a haltere whenexpressed in the levels of Ubx. Thus, the formation of divergent flight organs in Drosophila is notdependent on a specific Hox protein but on a specific Hox dose.Hox genes are intrinsically linked to the evolution of morphological diversity in animals.Therefore the role of the Hox dose was also tested from an evolutionary point of view amongseveral insect lineages. Results show that the Hox dose is for example pretty much the samebetween the forewing and hindwing primordia of the four-wing insect species Bombyx mori.Altogether, my results demonstrate that the specification of flight appendages is not aHox-independent developmental program and that the variation in the Hox dose is a way tomodify the wing size and shape, ultimately leading to a completely new balancing organ duringinsect evolution.

Midline convergence of organ primordia is an important mechanism for shaping the vertebrate body-plan at various stages of development, such as the morphogenesis of the heart and endoderm. Down regulation of wnt or noncanonical wnt signalling components, such as dishelleved (Dvl) or RhoA GTPase (RhoA), impairs midline convergence of the heart primordia and endoderm in zebrafish. This suggests that wnt signaling plays an important role in regulating midline convergence. At the early patterning stage of the zebrafish kidney, the two pronephric-glomerular primodia (PGP), which derive from intermediate mesoderm, converge towards the midline and fuse to form a functional pronephros. In contrast, during development of the mammalian kidney, the pronephros degenerates as the mesonephros develops without midline convergence. The hypothesis is thus that there is/are mechanisms underlying midline convergence of PGP in zebrafish, which is/are in addition to the control of the non-canonical wnt/Dvl/RhoA pathway and specific to kidney morphogenesis. In this study, the aim was to identify genetic factors that are specifically involved in the mechanism of PGP midline convergence by establishing a cell lineage tracing transgenic system with Cre-loxP, followed by the analysis of selected mutant embryos using the cell lineage tracing system, whole-mount in situ hybridization (WISH) and immunostaining. The cell lineage tracing system was generated, and tested. Constructs, in which β-actin promoter drives the transcription of the reporter genes, were microinjected into zebrafish embryos at 1- to 4-cell stages. The mRNAs in microinjected embryos (5 dpf) were analyzed by RT-PCR. The results show that the constructs induced indiscriminate alternative splicing. RNA splicing mechanisms were not affected by transcription termination when the polyA signal was located in introns. To provide an alternative approach, three mutants were selected after screening of available ENU zebrafish mutants. These mutants were chosen not only because of their genetic importance in cell adhesion and motility but also because of their respective developmental defects in tissues surrounding the PGP, such as the notochord (no tail, ntl), somite (spadetail, spt), and endodermal tissues (zygotic oneeyed pinhead, Zoep). Spt and ntl are key targets of fibroblast growth factor (FGF) signalling in the trunk and tail respectively. EGP-CFC gene oep is a Nodal signalling cofactor. Firstly, a rapid genotyping technique was developed, which was applied in identifying the mutant alleles. Since the tools for tracing PGP using transgenes were unavailable, the three mutants were analyzed by WISH and immunostaining. Zygotic mutation of Zoep causes a PGP midline convergence phenotype of variable severity due to maternal Oep effects. In more than 90% of Zoep-/- embryos, PGP midline convergence was impaired. Even though the abnormality could be observed as early as 15 hpf, the differentiation of the PGP was not affected. Heart primordial phenotypes were also observed but they did not correlate with that of the PGP phenotypes. Embryos homozygous for mutations in T-box transcription factors, ntl or spt had normal heart midline convergence phenotypes. PGP midline convergence abnormality was observed in spt-/- but not in ntl-/- prior to 36 hpf. In addition the extracellular matrix (ECM) might play a key role in the mechanisms of PGP midline convergence. Furthermore, PGP midline convergence proceeds from 10 hpf (the specification of intermediate mesoderm) to 48 hpf (fused pronephric glomerulus) in wild type zebrafish embryos. The process was quantified by 2D image analysis of the PGP distance. Prior to 18 hpf, PGP midline convergence is closely correlated with the midline convergence of mesoderm but not at later stages in Zoep-/-. Spt is essential for PGP but not for cardiac primordium midline convergence. Data from this research suggests that there is not one universal mechanism, which controls all the midline convergence of organ primordia. Indeed, specific factors, which depend on tissues and development stages, are also required.

Morphological and anatomical studies demonstrated the root formation characteristics of sweet potato. The presence and importance of preformed root primordia is recorded for the first time. On the vines root primordia are present in sets of four to ten adjacent to the leaf bases. These roots originate from the procambium on both sides of the leaf gap. Macroscopically the root tips of preformed root primordia protruding through the cortex and epidermis of the stems are prominent. The preformed root primordia produce adventitious roots, with pentarch, hexarch or septarch steles. Storage roots will under normal circumstances only originate from undamaged root primordia on the nodes of cuttings, or on nodes of newly formed vines, or from wound roots originating from the cut ends of the stem or leaf cuttings. Lateral roots originating from damaged root primordia, or directly from the adventitious roots, exhibit tetrarch steles and develop into fibrous roots without the potential to develop into storage roots. This understanding of the origin, anatomy and morphology of sweet potato roots should improve production practices, which will contribute to improved crop establishment and increased yield. Differences in the contribution of individual subterranean nodes to storage root yield were studied. On average cuttings with three subterranean nodes produced 3.7 storage roots, with 33.2% on subterranean node 1, 30.0% on node 2 and 36.8% on node3. However, in terms of fresh mass of the storage roots node 1 contributed 45.4%, node 2 contributed 27.1% and node 3 contributed 27.4%. The effect of temperature (20, 24, 28 and 32oC constant), orientation of cuttings (vertical vs. horizontal) and size of cuttings (1 or 3 nodes) on the development of adventitious roots was observed in plant growth chambers. Twenty-one days after planting, the longest total root length of 4m per plant was recorded from the 24oC growth chamber. The effect of soil moisture content on early root development was investigated by wetting and equilibrating sandy soil to 100, 80, 60 and 40% of field capacity. Although the 80% of field capacity treatment resulted in the best root development, differences among treatments were small, demonstrating the capacity of cuttings to successfully establish under a range of soil moisture contents. Changes in dry mass of storage roots, stems, and leaves of three sweet potato cultivars (Awasa-83, Bareda and Falaha) were studied at Awasa and Melkassa. At the final sampling the early maturing cultivar Falaha had diverted a higher proportion of the total dry mass into storage roots at Melkassa because of the early initiation and growth of storage roots. The late maturing cultivar Awasa-83 had a smaller proportion of the total dry mass diverted into the storage roots at both locations because of late root initiation and growth. The high yielding cultivars Bareda at Melkassa, and Awasa-83 at Awasa, had higher crop growth rates and higher net assimilation rates than the other cultivars. The effects of cultivar (Kudadie, Bareda and Awasa-83), planting position (horizontal and vertical), type of planting material (terminal cuttings with and without leaves) and cutting length (20, 25 and 30 cm) on the number and yield of storage roots were quantified in field trials at Awasa and Melkassa. Cultivar Kudadie produced the highest storage root yield at both locations. Horizontal planting of cuttings resulted in the highest total storage root yield at both locations. Cutting length did not affect storage root number and yield. The effect of population density (50,000, 55,555, 75,000, and 100,000 cuttings per hectare) on the performance of the three Ethiopian sweet potato cultivars was studied at Awasa. The highest planting density consistently produced the best root yield, indicating the potential to increase yields with plant populations much higher than normally used. Early maturing cultivar Falaha produced more small and medium storage roots per plant, while the intermediate cultivar Bareda produced more large storage roots. Copyright 2003, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. Please cite as follows: Belehu, T 2003, Agronomical and physiological factors affecting growth, development and yield of sweet potato in Ethiopia, PhD thesis, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-07262004-141704 / > / Thesis (PhD (Plant Production and Soil Science))--University of Pretoria, 2005. / Plant Production and Soil Science / unrestricted

[ES] Las leguminosas son un grupo de plantas consideradas de gran importancia por su valor nutricional para la alimentación humana y ganadera. Además, las familias de leguminosas se caracterizan por rasgos distintivos de desarrollo como su inflorescencia compuesta y su compleja ontogenia floral. Para comprender mejor estas características distintivas, es importante estudiar los genes reguladores clave involucrados en el desarrollo de la inflorescencia y la flor. El gen SUPERMAN (SUP) es un factor transcripcional de dedos de zinc (Cys2-Hys2) considerado como un represor activo que controla el número de estambres y carpelos en A. thaliana. Además, SUP está involucrado en la terminación del meristemo floral y el desarrollo de los tejidos derivados del carpelo. El objetivo principal de este trabajo fue la caracterización funcional del ortólogo de SUP en la leguminosa modelo Medicago truncatula (MtSUP). Logramos este objetivo en base a un enfoque de genética reversa, análisis de expresión génica y ensayos de complementación y sobreexpresión. Nuestros resultados muestran que MtSUP es el gen ortólogo de SUP en M. truncatula. MtSUP comparte algunos de los roles ya descritos para SUP con algunas variaciones. Curiosamente, MtSUP controla la determinación del meristemo inflorescente secundario (I2) y de los primordios comunes (CP) a pétalos y estambres. Por tanto, MtSUP controla el número de flores y de pétalos-estambres que producen el meristemo I2 y los primordios comunes, respectivamente. MtSUP muestra funciones novedosas para un gen de tipo SUP, desempeñando papeles clave en los meristemos que confieren complejidad de desarrollo a esta familia de angiospermas. Este trabajo permitió identificar a MtSUP, un gen clave que forma parte de la red reguladora genética que subyace al desarrollo de la inflorescencia compuesta y de las flores en la leguminosa modelo M. truncatula. / [CA] Les lleguminoses són un gran grup de plantes considerades de gran importància pel seu valor nutricional per a l'alimentació humana i ramadera. A més, les famílies de lleguminoses es caracteritzen per trets distintius de desenrotllament com la seua inflorescència composta i la seua complexa ontogènia floral. Per a comprendre millor estes característiques distintives, és important estudiar els gens reguladors clau involucrats en la inflorescència i el desenrotllament floral. El gen SUPERMAN (SUP) és un factor transcripcional de dits de zinc (Cys2-Hys2) considerat com un repressor actiu que controla el nombre d'estams i carpels en A. thaliana. A més, SUP està involucrat en la terminació del meristemo floral i el desenrotllament dels teixits derivats del carpel. "L'objectiu principal d'este treball va ser la caracterització funcional de l'ortòleg de SUP en la lleguminosa model Medicago truncatula (MtSUP) . Aconseguim l'objectiu amb base en un enfocament genètic invers, anàlisi d'expressió gènica i assajos de complementació i sobreexpressió. Els nostres resultats mostren que MtSUP és el gen ortòleg de SUP en M. truncatula. MtSUP compartix alguns dels rols ja descrits per a SUP amb variacions. Curiosament, MtSUP està involucrat en la determinació del meristemo de la inflorescència secundària (I2) i els primordios comuns (CP). Per tant, MtSUP controla el nombre de flors i pètals-estams que produïxen el meristemo I2 i els primordios comuns, respectivament. MtSUP mostra funcions noves per a un gen tipus SUP, exercint papers clau en els meristemos que conferixen complexitat de desenrotllament a esta família d'angiospermes. "Este treball va permetre identificar a MtSUP, un gen clau que forma part de la xarxa reguladora genètica darrere de la inflorescència composta i el desenrotllament de flors en la lleguminosa model M. truncatula. / [EN] Legumes are a large group of plants considered of great importance for their nutritional value in human and livestock nutrition. Besides, legume families are characterized by distinctive developmental traits as their compound inflorescence and complex floral ontogeny. For a better understanding of these distinctive features is important to study key regulatory genes involved in the inflorescence and floral development. The SUPERMAN (SUP) gene is a zinc-finger (Cys2-Hys2) transcriptional factor considered to be an active repressor that controls the number of stamens and carpels in A. thaliana. Moreover, SUP is involved in the floral meristem termination and the development of the carpel marginal derived tissues. The main objective of this work was the functional characterization of the SUP orthologue in the model legume Medicago truncatula (MtSUP). We achieved this objective based on a reverse genetic approach, gene expression analysis, and complementation and overexpression assays. Our results show that MtSUP is the orthologous gene of SUP in M. truncatula. MtSUP shares some of the roles already described for SUP with variations. Interestingly, MtSUP controls the determinacy of the secondary inflorescence (I2) meristem and the common primordia (CP). Thus, MtSUP controls the number of flowers and petal-stamens produced by the I2 meristem and the common primordia respectively. MtSUP displays novel functions for a SUP-like gene, playing key roles in the meristems that confer developmental complexity to this angiosperm family. This work allowed to identify MtSUP, a key gene that participates in the genetic regulatory network underlying compound inflorescence and flower development in the model legume M. truncatula. / I would like to thanks the Spanish Ministry of Economy and Competitiveness for the grant (MINECO; BIO2016-75485-R) that supported this work. Special thanks to the Generalitat Valenciana for funding my doctorate with the Santiago Grisolía predoctoral scholarships / Rodas Méndez, AL. (2021). MtSUPERMAN controls the number of flowers per inflorescence and floral organs in the inner three whorls of Medicago truncatula [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/171474