Letteratura scientifica selezionata sul tema "Flowering"

The Japanese sato-zakura, literally “village cherries”, represent perhaps the most popular subject of dendrology and ornamental horticulture. The authors rose to the occasion to write an extraordinary account of Japanese cherries and shed more light on a still confused group of these aristocratic flowering trees. Kuitert teaches at the Kyoto University of Art and Design while Peterse is a dedicated plant breeder and researcher of the Japanese flowering cherries. Rarely do professors have the time, or take the time, needed to solely write such a thoroughly prepared text. Both Dutchmen paid attention to detail, and the result is a well-written, high-quality product.

Abstract Flowering is the developmental transition from the vegetative to the reproductive phase. FLOWERING LOCUS T (FT), SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1), and LEAFY (LFY) are floral integrators. These genes are repressed by several floral repressors including EARLY FLOWERING3 (ELF3), SHORT VEGETATIVE PHASE (SVP), TEMPRANILLO1 (TEM1), and TEM2. Although gibberellin (GA) promotes flowering by activating the floral integrator genes, the exact molecular mechanism remains unclear. DELLAs are negative regulators in GA signaling and act as coactivators of the transcription factor GAI ASSOCIATED FACTOR 1 (GAF1). GAs convert the GAF1 complex from a transcriptional activator to a repressor. Here, we show that GAF1 functions in the GA-dependent flowering pathway by regulating FT and SOC1 expression in Arabidopsis thaliana. We identified four flowering repressors, ELF3, SVP, TEM1, and TEM2, as GAF1-target genes. In response to GAs, GAF1 forms a transcriptional repressor complex and promotes the expression of FT and SOC1 through the repression of four flowering repressor genes, ELF3, SVP, TEM1, and TEM2.

Les plantes ont longtemps intrigué les scientifiques, qui, avec son importance vitale pour la planète, sa beauté et l'énorme quantité de formes ayant, les rend un sujet attrayant pour la recherche. Un aspect intéressant est la création d'un modèle virtuel capable de simuler de vraies plantes avec un degré élevé de précision. L'objectif de notre étude est les plantes à fleurs, qui jouent un rôle énorme dans notre vie de fins nutritives et médicales à l'embellissement de l'environnement . L'obtention d'un modèle géométrique exacte d'une fleur est très utile, car elle joue un rôle important dans la validation du modèle virtuel. Par ailleurs, la visualisation de paramètres non directement traçables dans les plantes à fleurs vivantes est d'une grande aide à l'étude de la physiologie. L'énorme biodiversité entre les différentes parties d'un spécimen et entre les différents spécimens fournit une vaste zone d'objectifs qui la synthèse d'image doit contester. Modéliser des fleurs est un sous-ensemble d'un espace de recherche beaucoup plus vaste que la modélisation de plantes. Les plantes à fleurs ont des caractéristiques structurelles qui les rendent différentes des structures d'arbres, d’arbustes ou de l’herbe. A ce jour, on ne tient pas une grande importance à essayer cette ligne de recherche d'une façon particulière et en général a été classé dans le contexte plus large de la modélisation des plantes. Nous avons choisi d’utiliser le «L-systems» pour la procédure de la modélisation, et comme base pour notre recherche. Il y a différents mécanismes de catégorisation topologie de la plante dans chacune des étapes de sa croissance. Pour construire le plan de la structure d'une plante, avec une courte grammaire, quelques lignes étaient quelque chose qui dès le premier moment a suscité l'intérêt et par la suite évolué en quelques systèmes d'interprétation géométriques pour la modélisation des plantes. Notre objectif est d'étudier les moyens efficaces de décrire la structure des plantes à fleurs en utilisant L-systems. Tout d'abord, nous proposons de représenter les formes des feuilles, pétales, étamines, carpelles, etc. Avec une extension de L-systems - un modèle basé sur trois cartes généralisées dimensions - 3Gmaps L-systèmes, qui peut être appliquée avec succès pour la modélisation des plantes à fleurs. La description de la grammaire de la structure des plantes à fleurs fournit un nombre illimité de ses interprétations géométriques. Deuxièmement, nous allons améliorer le processus d'écriture de la grammaire par l'ajout d'une nouvelle fonctionnalité de paramétrage interactif. Troisièmement, nous allons proposer une nouvelle méthode de modélisation inverse des plantes à fleurs, où l'utilisateur peut définir de manière interactive les caractéristiques des fleurs. L'algorithme utilise cette information comme une entrée, qui est ensuite analysée et codée en tant que L -systèmes grammaire. Enfin, nous allons présenter une méthode pour créer des clairières de fleurs virtuelles à l'aide de gestes Kinect. Nous voulons faire remarquer que notre travail a été fait avec la plateforme de logiciel 3Gmaps L- système développé dans le cadre de la thèse d'intégrer toutes les techniques proposées
Plants have always intrigued scientists as besides of its sheer importance for the earth, their beauty and enormous variety of shapes tempt to thoroughly inquire about its nature. One of the aspects of this inquiry is the creation of the virtual model in order to mimic real plants to a high degree of accuracy. The focus of our study is the flowering plants, which play a huge role in our life from nutritive and medical purposes to beautifying the environment. Obtaining an accurate geometrical model of a flower is quite useful as it plays an important role in the validation of the virtual model. Besides, the visualization of parameters not traceable directly in living flowering plants is a stand-by in studying their physiology. A huge biological diversity both within and between individuals provides a vast area of objectives which the image synthesis must challenge.Flower modelling constitutes a part of a larger research area, plant modelling. Flowering plants have their particular structural features which are different from the structure of trees, bushes or grass. Still not a lot of emphasis has been placed to date on this problem, as it was categorized within the modelling of plants in general. We chose a procedural modeling using L-systems as a base of our research. L-system is a very powerful method of plant simulation. It provides a means of characterizing the topology of a plant at every stage of its growth. Grasping the plant structure with just several lines of grammar attracted immediate interest and later on evolved into several powerful geometrical interpretation system used in plant modelling. Our purpose is to study efficient ways of describing the structure of flowering plants by means of L-systems. First, we will propose to represent the shapes of leafs, petals, stamens, carpels, etc. with an extension of L-systems – a model based on three dimensional generalized maps – 3Gmaps L-systems, which can be successfully applied for the modelling of flowering plants. The grammar description of the structure of the flowering plants provides an unlimited number of its geometrical interpretations. Second, we will improve the process of grammar writing by adding a new functionality of interactive parameter adjustment. Third, we will propose a new method of inverse modelling of flowering plants, where the user can interactively define the flower characteristics. The algorithm uses this information as an input, which is then analyzed and coded as L-systems grammar. Finally, we will present a method for creating virtual glades of flowers using Kinect gestures. We want to remark that our work has been done with 3Gmaps L-system software platform developed in the scope of the thesis to integrate all the proposed techniques

The proportion of resources which an organism devotes to reproduction has been assumed to be of great evolutionary and ecological significance. However, in previous studies of reproductive allocation (RA) in plants, there has been no consensus of precisely what is being measured nor how it should be measured. An attempt was made to determine the 'best' method of measuring RA and then apply this to a range of species with differing ecological strategies. Under nutrient stress caused by a low N treatment Taraxacum officinale and Poa annua were found to maintain their RA despite up to 4 fold reductions in biomass. Under K and P deficient conditions there was a preferential allocation of these elements to reproductive structures in Taraxacum. Ruderal plants therefore, seem to maintain biomass RA and seed quality despite nutrient stress. Although the nutrient RA in Taraxacum was found to be significantly different from biomass RA (KRA = 71% PRA = 66% BRA= 51.7%) the extent of the difference varied between treatments. There was therefore no obvious alternative currency to biomass. The evolutionary consequences of reproduction may also be measured through a reproductive cost which may take the form of reduced future reproduction, survival or growth. Prevention of flowering in Digitalis purpurea resulted in an increase in the number of axillary buds produced, Similarly in Plantago lanceolata removal of flowers resulted in a 3 fold increase in production of buds. In both species realisation of a reproductive cost was prevented. The importance of individual variability was noted. The importance of plant morphology was evident and was used to explain some of the anomalous RA values in the comparative experiment. RA values were collected for 40 species of Gramineae. RA was a useful ecological index which emphasised the ruderal element of a plant's strategy. When used in conjunction with other parameters particularly Rmax, RA produced a meaningful classification of species in terms of their ecological strategy.

Thesis (PhD(Agric))--University of Stellenbosch, 2000.
ENGLISH ABSTRACT: Little is understood regarding flowering in the genus Protea. The information available on inflorescence initiation and development in the family Proteaceae was reviewed and discussed. A number of experiments were conducted to investigate inflorescence initiation and development, and their manipulation for commercial production, in selected Protea cultivars, in the Western Cape, South Africa (33°S, Protea species can be allocated into groups according to similar times of flower initiation and of harvest. The stages occurring during flower initiation, and their synchrony relative to shoot growth were investigated for three cultivars, viz. Protea cv. Carnival (P. compacta x P. neriifolia), Protea cv. Lady Di (P. compacta x P. magnifica) and Protea cv. Sylvia (P. eximia x P. susannae), when flower initiation occurred on the spring growth flush. For all three cultivars the spring flush was preformed and enclosed in the apical bud before spring budbreak. During elongation of the spring flush the apical meristem produced floral primordia which differentiated into involucral bracts. After completion of the spring flush meristematic activity continued, to produce floral bracts with florets in their axils. The three cultivars showed differences and similarities in the time of budbreak, and the rates of shoot growth, appendage formation and flower development. The presence of mature leaves on an over-wintering shoot is essential for inflorescence initiation on the spring growth flush of 'Carnival'. Inflorescence initiation in 'Carnival' started at spring budbreak, and production of involucral bracts occurred concurrently with spring flush elongation. Shoots were defoliated at different degrees of severity at intervals from pre- to post- spring budbreak. Total defoliation applied earlier than 6-7 weeks before spring budbreak prevented flowering. Defoliation closer to spring budbreak affected characteristics of the spring flush and the inflorescence subtended by the spring flush. Effects were most marked following total defoliation and diminished with less severe treatments imposed by partial defoliation. Total defoliation applied before spring budbreak resulted in slower inflorescence development and lead to later anthesis. Defoliation treatments applied after completion of spring flush elongation had no effect on either vegetative or reproductive spring growth. The requirement for mature overwintering leaves to effect inflorescence initiation in 'Carnival' suggests that environmental factors, such as low temperature and daylength may play an inductive role. Shoots were in the induced state and committed to flowering 6-7 weeks before spring budbreak. A change in source size and position subsequent to different severalties of defoliation in 'Carnival' lead to reduced dry mass accumulation and altered partitioning. Mature leaves on the overwintering shoot supported growth of the spring flush and the early stages of inflorescence development. When these leaves were removed by total defoliation dry mass accumulation in the spring flush was reduced. A hierarchy of priorities between competing sinks was revealed by defoliation during growth of the spring flush and concomitant inflorescence development: formation of involucral bracts> leaf growth> stem elongation. Dry mass accumulation of the inflorescence subtended by the spring flush was supported by the spring flush leaves and was only indirectly affected by defoliation. Treatments which resulted in the production of a weaker spring flush lead to a reduction in dry mass accumulation of the inflorescence. Different severalties of partial defoliation, whereby either upper or lower leaves were removed from a shoot, indicated that the position of leaves relative to the active sink is more important, with respect to source availability, than the number of leaves on the shoot. Mature overwintering leaves are essential in 'Lady Di' for shoots to achieve the induced state for flowering; and are also crucial to the early stages of inflorescence initiation. Defoliation applied before formation of involucral bracts was complete prevented flowering. Defoliated shoots either remained vegetative or produced inflorescences which aborted. Reserve carbohydrates in the stem and leaves of overwintering shoots were low, and early growth and development of both the spring flush and inflorescence were, therefore, supported by current photosynthates from the overwintering leaves. Likewise, reserve carbohydrates available in the flowering shoot were insufficient to account for the dry mass increase during the major portion of growth of the spring flush and inflorescence. This rapid increase in dry mass occurred after elongation of the spring flush was complete and was supported by current photosynthates from the leaves of the spring flush. Defoliation treatments that did not prevent inflorescence initiation, had no effect on inflorescence development, and flowering time of 'Lady Di' was not delayed by defoliation. 'Sylvia' has an open window for inflorescence initiation and can initiate flowers throughout the year. Despite the 'open window' inflorescences are initiated more readily on the spring flush, when it is subtended by one or more overwintering shoots. This may be the expression of a facultative response to inductive conditions for which 'Carnival' and 'Lady Di' have an obligate requirement. The date of pruning affected flowering time of 'Sylvia' by influencing on which flush inflorescence initiation occurred, and the harvest could be manipulated to fall within the optimum marketing period for export to Europe. Flowers initiated on the spring flush reach anthesis in January and February; on the first summer flush predominantly in April and May; on the second summer flush in July and August; and on the autumn flush in November and December. Thus, shoots harvested within the optimum marketing period (September to February) initiated inflorescences on the autumn and spring flushes. Due to the readiness of shoots to initiate inflorescences on the spring flush many shoots harvested in January and February (following initiation in the previous spring) were short and were rendered unmarketable. For commercial production pruning in July is recommended. Long flowering stems will be harvested in October to November of the following year. Since the vegetative and reproductive cycles necessary to produce inflorescences on long stems span more than a year, a biennial cropping system is recommended.
AFRIKAANSE OPSOMMING: Bloeiwyse-inisiasie en -ontwikkeling, en die manipulasie daarvan, van geselekteerde cultivars van die genus Protea. Min word verstaan van blomvorming in die genus Protea. Die beskikbare inligting oor die bloeiwyse-inisiasie en -ontwikkeling in die familie Proteaceae is nagegaan en bespreek. 'n Aantal eksperimente is uitgevoer waarin geselekteerde Protea cultivars van die Wes-Kaap, Suid-Afrika (33°S, 19°0) se bloeiwyse-inisiasie en -ontwikkeling, asook die manipulasie daarvan vir kommersiële produksie ondersoek is. Protea spesies kan in groepe ingedeel word op grond van blominisiasietye en oestye wat ooreenstem. Die verskillende stadiums van blominisiasie en hulle sinchronisering relatieftot stingelgroei is ondersoek vir drie kultivars, naamlik Protea cv. Carnival (P. compacta x P. neriifolia), Protea cv. Lady Di (P. compacta x P. magnifica) en Protea cv. Sylvia (P. eximia x P. susannae) tydens blominisiasie op die lentegroeistuwing. By al drie die kultivars was die lentegroeistuwing reeds gevorm en omsluit in die apikale knop voor die lente-knopbreking. Gedurende die verlenging van die lentegroeistuwing het die apikale meristeem blomprimordia, wat in bloeiwyseomwindselskutblare gedifferensieer het, geproduseer. Na voltooiing van die lentegroeistuwing, het meristematiese aktiwiteit voortgeduur en blomskutblare met blommetjies in hulle oksels is gevorm. Die drie kultivars het verskille en ooreenkomste vertoon tydens die periode van knopbreking, asook in die tempo van stingelgroei, aanhangselformasie en blomontwikkeling. Die teenwoordigheid van volwasse blare op 'n oorwinteringstingel is noodsaaklik vit bloeiwyse-inisiasie op die lentegroeistuwing van 'Carnival'. Bloeiwyse-inisiasie in 'Carnival' het met lente-knopbreking begin en die produksie van bloeiwyseomwindselblare het gelyktydig met lentegroeistuwing verlenging plaasgevind. Stingels is met tussenposes, van voor tot na die lente-knopbreking, en met verskillende grade van felheid, ontblaar. Algehele ontblaring vroeër as 6-7 weke voor die lente-knopbreking het blomvorming verhoed. Ontblaring nader aan die lenteknopbreking het 'n invloed gehad op die eienskappe van die lentegroeistuwing asook die bloeiwyse gedra deur die lentegroeistuwing. Die effek was die duidelikste sigbaar by algehele ontblaring en het verminder namate die behandeling minder fel geword het by gedeeltelike ontblaring. Algehele ontblaring wat voor die lente-knopbreking gedoen is, het gelei tot stadiger bloeiwyse-ontwikkeling en later antese. Ontblaringsbehandelings wat na die voltooiing van die lentegroeistuwing verlenging toegepas is, het geen effek op die vegetatiewe of die reproduktiewe lentegroei gehad me. Die nodigheid van volwasse oorwinteringsblare vir bloeiwyse-inisiasie in 'Carnival' dui daarop dat omgewingsfaktore soos lae temperature en daglengte 'n induktiewe rol kan speel. Stingels was in die geïnduseerde toestand en verbind tot blomvorming 6-7 weke voor die lente-knopbreking. 'n Verandering in oorspronggrootte en -posisie as gevolg van verskille in die felheid van ontblaring by 'Carnival', het gelei tot verminderde droë-massa-akkumulasie en veranderde verdeling. Volwasse blare op die oorwinteringstingel het die groei van die lentegroeistuwing en die vroeë stadiums van bloeiwyse-ontwikkeling ondersteun. Toe hierdie blare verwyder is in 'n algehele ontblaring, het die droë-massa-akkumulasie in die lentegroeistuwing verminder. 'n Hiërargie van prioriteite tussen kompeterende sinke is blootgelê tydens ontblaring gedurende die lentegroeistuwing en saamlopende bloeiwyse-ontwikkeling: vorming van bloeiwyse-omwindselblare > blaargroei > stamverlenging. Droë-massa-akkumulasie van die bloeiwyse onderspan deur die lentegroeistuwing is ondersteun deur die blare van die lentegroeistuwing en is slegs op 'n indirekte wyse deur ontblaring geaffekteer. Behandelings wat tot die produksie van 'n swakker lentegroeistuwing gelei het, het tot 'n vermindering in die droë-massaakkumulasie van die bloeiwyse gelei. Verskille in die felheid van gedeeltelike ontblaring, waartydens óf die boonste óf die onderste blare van 'n stingel verwyder is, het aangetoon dat die posisie van die blare relatief tot die aktiewe sink belangriker is, met betrekking tot die beskikbaarheid van die oorsprong, as die aantal blare op die stingel. By 'Lady Di' is volwasse oorwinteringsblare noodsaaklik VIr stingels om die geïnduseerde stadium van blomvorming te bereik en hulle is ook van die uiterste belang in die vroeë stadiums van bloeiwyse-inisiasie. Waar ontblaring gedoen is voordat die vorming van bloeiwyse-omwindsel voltooi was, het blomvorming nie plaasgevind nie. Ontblaarde stingels het ófvegetatief gebly ófbloeiwyses geproduseer wat geaborteer het. Reserwe-koolhidrate in die stam en blare van die oorwinteringstingels was laag en die vroeë groei en ontwikkeling van beide die lentegroeistuwing en die bloeiwyse is dus deur die bestaande fotosintate van die oorwinteringsblare onderhou. Net so was die reserwe-koolhidrate beskikbaar in die blomdraende stingels nie voldoende om die toename in droë massa gedurende die grootste deel van die groei van die lentegroeistuwing en die bloeiwyse te verklaar nie. Hierdie vinnige toename in droë massa het plaasgevind nadat die verlenging van die lentegroeistuwing voltooi was en is deur die bestaande fotosintate van die blare van die lentegroeistuwing onderhou. Ontblaringsbehandelings wat nie bloeiwyse-inisiasie verhoed het nie, het geen effek op bloeiwyse-ontwikkeling gehad nie en die blomtyd van 'Lady Di' is nie deur ontblaring vertraag nie. 'Sylvia' beskik oor 'n oop venster vir bloeiwyse-inisiasie en kan regdeur die jaar blomme inisieer. Ten spyte van die 'oop venster', word bloeiwyses tog meer geredelik in die lentegroeistuwing geïnisieer, wanneer dit deur een of meer van die oorwinteringstingels gedra word. Dit mag die uitdrukking wees van 'n fakultatiewe respons op induktiewe toestande wat vir 'Carnival' en 'Lady Di' 'n verpligte vereiste is. 'Sylvia' se blomtyd is deur die snoeidatum geaffekteer omdat die snoeidatum 'n invloed gehad het op die keuse van by watter groeistuwing bloeiwyse-inisiasie plaasgevind het. Die oestyd kon gemanipuleer word om binne die optimum bemarkingstydperk vir uitvoer na Europa te val. Blomme wat op die lentegroeistuwing geïnisieer is, bereik antese in Januarie en Februarie; dié wat op die eerste somergroeistuwing geïnisieer is, bereik antese hoofsaaklik in April en Mei; dié wat op die tweede somergroeistuwing geïnisieer is, bereik antese in Julie en Augustus en dié wat op die herfsgroeistuwing geïnisieer is, bereik antese in November en Desember. Stingels wat in die optimum bemarkingsperiode (September tot Februarie) geoes is, het dus bloeiwyses op die herfs- en lente-groeistuwings geïnisieer. As gevolg van die gereedheid van stingels om bloeiwyses op die lentegroeistuwings te inisieer, was baie van die stingels wat in Januarie en Februarie geoes is, kort en kon nie bemark word nie. Vir kommersiële doeleindes word snoei in Julie aanbeveel. Lang blomdraende stingels sal in Oktober en November van die volgende jaar geoes word. Aangesien die vegetatiewe en reproduktiewe siklusse wat nodig is om bloeiwyses met lang stingels te produseer oor meer as fn jaar strek, word fn tweejaarlikse oesinsamelingstelsel aanbeveel.

Analysis of photomorphogenic mutants and transgenic plants provides further insights into the roles of individual phytochrome species. The presence of a significant early-flowering response to low R/FR ratio has been reveled in Arabidopsis phyB mutants, that are also homozygous for a late-flowering mutation. This firstly, implicates at least one other novel phytochrome species, in addition to phytochrome B, in the low R/FR ratio-mediated early- flowering response. Secondly, identifies features that are likely to represent a loss-of-function mutant in this novel phytochrome species. Examination of the Arabidopsis elg mutant, a putative novel phytochrome loss-of- function mutant, defines ELG as a novel gene that influences elongation growth. What is more, ELG appears to act independently of phytochrome and GA. However, H4S seedlings overexpress the Arabidopsis HAT4 transgene, which is proposed to be down-regulated by a novel phytochrome. Thus, physiological analysis of Arabidopsis H4S seedlings reveal characteristics that may be representative of seedlings with a deficiency in a novel phytoclirome species. The physiological effects of phytochrome overexpression have also been examined in DN and SD N. tabacum, cv. Hicks. Allelic series overexpressing phytochrome A, phytochrome B and phytochrome C were generated for this purpose. These analyses provide a full characterisation of a phytochrome B-overexpression phenotype in tobacco, previously unreported. They also provide the first evidence that phytochrome C is a functional photoreceptor, and the first description of a phytochrome C-overexpression phenotype. DN and SD N. tabacum differ only with respect to the MM locus, which confers SD photoperiodicity. Hence, these plants are ideally suited for the comparative analysis of phytoclirome overexpression on photoperiodic perception. Alterations in the NB-mediated flowering response in transgenic plants suggests that phytochrome A- and B-overexpression disrupt photoperiodic timimg. However, the behaviour of N. tabacum overexpressing phytochrome C suggests that the phytochrome C transgene may specifically affect MM transduction.

Flowering plants exhibit a particular pattern of seasonal cycle to suit the changing seasons for maximum survival and reproduction success. Temperature plays a key role in controlling flowering time of many plants. Fragaria vesca f. vesca is seasonal flowering and runnering. While it is not known to require vernalisation to flower, cool and cold temperatures affect its vegetative and reproductive development. An F. vesca VIN3-like (FvVIL) mRNA was isolated and characterised. It has a PHO finger domain, a FNIII domain and a VIO domain, which characterise the VIN3 family genes of Arabidopsis thaliana. It contains four exons, and it is more similar to VIL2 than other VIN3 family genes of Arabidopsis thaliana.• The coding sequence of FvVIL contains 2208 nucleotides; six and nine nucleotides less than that of Prunus persica and Malus x domestica respectively with 78% identical. In experiments to develop a transformation system, F. v. semperflorens had higher in vitro regeneration than F. vesca. Both species could not regenerate from either leaf or petiole segments on medium without plant growth regulators. Plantlet regeneration from leaf explants was better at 1 mg L-1 than 2, 3 and 4 mg L-1 BAP. Plantlet regeneration from F. v. semperflorens petiole explants was best achieved at 0.1 mg L-1 IBA compared to 0, 0.2 and 0.4 mg L-1. F. vesca initiated flowers after eight weeks at 12°C under 8h short-days (SO). Plants chilled at 4°C produced fewer leaves than plants chilled at 8 or 12°C. Extended exposure to cool or chill temperature promoted more synchronised vegetative growth than a shorter exposure. Prolonged cool temperature promoted petiole elongation more than a short period of chilling. Extended chilling at 4°C for eight weeks in SO greatly stimulated F. vesca runner production after transfer to 20°C long-day (LO) conditions. There was no evidence suggesting dormancy breaking had occurred. Chilling delayed the emergence of inflorescences in F. vesca. Flower initiation was stopped by prolonged chilling but not by a short period of chilling.

The angiosperm order Malpighiales includes \(\sim 16,000\) species and constitutes up to 40% of the understory tree diversity in tropical rain forests. Despite remarkable progress in angiosperm phylogenetics during the last 20 years, relationships within Malpighiales have remained poorly resolved, possibly due to its rapid rise during the mid-Cretaceous. Using phylogenomic approaches, including analyses of 82 plastid genes from 58 species, we identified 12 new clades in Malpighiales and substantially increased resolution along the backbone (Chapter 1). This greatly improved phylogeny revealed a dynamic history of shifts in net species’ diversification rates across Malpighiales, with bursts of diversification noted in the Barbados cherries (Malpighiaceae), cocas (Erythroxylaceae), and passion flowers (Passifloraceae). We also found that commonly used a priori approaches for partitioning data in similar large-scale analyses, by gene or by codon position, performed poorly relative to the use of partitions identified a posteriori using a Bayesian mixture model. Another aspect of my thesis focused on investigating horizontal gene transfer (HGT) in Malpighiales. Recent studies have suggested that plant genomes have undergone potentially rampant HGT. Parasitic plants have provided the strongest evidence of HGT, which appears to be facilitated by the intimate physical association between the parasites and their hosts. Using phylogenomic approaches, we analyzed the nuclear transcriptome (Chapter 2) and mitochondrial genome (Chapter 3) of the holoparasite Rafflesiaceae, which represents an enigmatic subclade of Malpighiales. Our analyses show that several dozen actively transcribed nuclear genes, and as many as 34–47% of its mitochondrial gene sequences, show evidence of HGT depending on the species. Some of these HGTs appear to have maintained synteny with their donor and recipient lineages suggesting that vertically inherited genes have likely been displaced via homologous recombination, as is common in bacteria. Finally, our results establish for the first time that although the magnitude of HGT involving nuclear genes is appreciable in these parasitic plants, HGT involving mitochondrial genes is substantially higher. Moreover, the elevated rate of unidirectional host-to-parasite gene transfer raises the possibility that HGTs may provide a fitness benefit to Rafflesiaceae for maintaining these genes.

Abstract This chapter covers the various factors affecting the transformation of vegetative growth to reproductive phase of guava trees, and the phenology, anthesis and pollination in guava. The agricultural practices for regulating crop production are also discussed.

The paper presents the three-year results of the effect of basic climatic parameters on the flowering of 12 apricot cultivars in conditions of Čačak. The significant differences in the beginning, progression and duration of flowering among years were determined. The beginning of flowering in 2020 was on March 12, in 2021 on March 1, and in 2022 on March 24. Flowering phenophase in one cultivar lasted between 6 and 9 days in 2022 and between 8 and 16 days in 2021. Differences in the beginning of flowering among cultivars were more pronounced in years with earlier flowering date.

To assess the effect when creating flower beds from tagetes in the open field, an indicator of flowering productivity was used. Based on the determination of this indicator in the phase of mass flowering of plants, it was revealed that in African Tagetes, in comparison with the rejected, the structure of the flower garden was formed due to larger spherical inflorescences, but with a lower density of planting. Due to the morphological features of African Tagetes hybrids, flower beds have been created from perfectly aligned terry baskets. The average productivity of flowering was 41.3 pcs / m². Analysis of variance showed that the variation in flowering productivity was more dependent on the species than on the studied Tagetes hybrid.

In temperate climates, fruit crop yields are primarily determined by environmental conditions, especially during dormancy and in the early stages of their phenological development. Climate anomalies, with both warmer spring temperatures and greater temperature fluctuation, have altered phenology, leading to a greater risk of spring frost damage to orchards. The sweet cherry (Prunus avium), like other fruit species in the temperate climate, needs to accumulate a cultivar-specific quantity of chilly units during the endodormancy, and heat units during ecodormancy for breaking of dormancy and flowering properly in spring. The knowledge of chilly and heat requirements is important in the selection of the appropriate cultivars for the produces in a particular area. This study aims to estimate growing degree hours (GDH) requirements up to flowering for 12 cherry cultivars grown in the basic regions of industrial cherry production in Bulgaria. Phenological and hourly temperature observations for nine years (2002-2010) were used to perform this study. The GDH were calculated as the sum of temperatures above 5�C accumulated from the breaking of dormancy to the flowering. The heat requirements (HR) for flowering ranged between 1908-3868 GDH. The results indicate that the flowering time of cherry in the studied regions is influenced by GDH. Identification of cultivars with higher HR and later flowering is important for cherry production, especially in regions with frequent late spring frosts occurrence.

The analysis of the content of rutine in buckwheat (Fagopyrum esculentum Moench) was performed under the influence of agroecological factors in the area of Nišićka Visoravna (Sarajevo) during 2019. A field experiment in which the content of rutines in different development phenophases of buckwheat (beginning of flowering, full flowering, maturation) was set up and analyzed. Fresh plant material was used for analysis, and the hydrolate production process was carried out by steam distillation. The distilled buckwheat solution was analyzed by HPLC method at the Institute of Agromediterranean Faculty in Mostar. The highest content of rutine in the research period was recorded in the developmental phase of full flowering 28 mg/100 g, in the phase of maturation it is 21 mg/100 g and the lowest content was found in the phase of the beginning of flowering 19 mg/100 g.

A field experiment was conducted at the research field station of the Field Crops Department, College of Agricultural Engineering Sciences, University of Baghdad, Jadriya, during the year 2017-2018— the experiment aimed to study the effect of growth regulator gibberellin on broad bean growth and yield. In a factorial experiment according to RCBD design, the first factor was gibberellin spraying stages (the beginning of vegetative growth and the beginning of flowering), while the second factor was gibberellin concentrations (100, 200, and 300 mg L1), in addition to the comparison treatment, which was sprayed with water only. It was flowering by giving it the highest average plant height, number of pods, and seeds per pod. The results showed the superiority of the spraying stage at the beginning of flowering by giving it the highest mean of plant height, number of pods, and number of seeds per pod. In the spraying phase at the beginning of flowering (S2) and a concentration of 300 mg L-1, the highest average number of pods per plant reached 20.00 pods per plant. In comparison, a treatment at the beginning of flowering (S2) and a concentration of 200 mg L-1 achieved the highest average number of seeds per pod, reached 4.50 Seed in the pod, and achieved the spraying stage at the beginning of vegetative growth (S1) and the concentration was 200 mg L-1, the highest average was 133.3 g. We conclude from this study that spraying gibberellin at the beginning of flowering affected growth indicators and increased yield by increasing the averages of its components, especially by increasing the concentration of gibberellin at 200 and 300 mg L-1.

A series of 10 water-exchange studies were conducted from 2019 to 2021 at two sites, Clover Island and Osprey Point, within the McNary Pool of the Columbia River on the Oregon-Washington border. Six of the studies incorporated a barrier curtain or bubble curtain, whereas the other four studies did not include any device to mitigate water exchange. Once annually, diquat aquatic herbicide was applied concurrently with rhodamine water tracing (RWT) dye at the Osprey Point site (2019–2021) to control flowering rush. An additional plot, Clover Island Reference, served as the nontreated control to the Osprey Point treatment plot. Pre- and posttreatment vegetation surveys were conducted in 2019, 2020, and 2021 to determine flowering rush control, treatment impacts to water quality, and nontarget species response. This study sought to (1) document the use of barrier curtains and bubble curtains as potential methods for reducing water exchange and increasing herbicide concentration exposure times within potential flowering rush treatment areas, (2) evaluate bulk water exchange and selective control of flowering rush under varying reservoir operations, and (3) use the results from these studies to provide guidance for managing submersed flowering rush infestations on the McNary Pool, Columbia River, and similar run-of-the-river impoundments.

Annual plants have developed a range of different mechanisms to avoid flowering (exposure of reproductive organs to the environment) under adverse environmental conditions. Seasonal environmental events such as gradual changes in day length and temperature affect the timing of transition to flowering in many annual and perennial plants. Research in Arabidopsis and additional species suggest that some environmental signals converge on transcriptional regulation of common floral integrators such as FLOWERING LOCUS T (FT). Here we studied environmental induction of flowering in the model legume Medicago truncatula. Similarly to Arabidopsis, the transition to flowering in M. truncatula is hastened by long photoperiods and long periods of vernalization (4°C for 2-3 weeks). Ecotypes collected in Israel retain a vernalization response even though winter temperatures are way above 4°C. Here we show that this species is also highly responsive (flowers earlier) to mild ambient temperatures up to 19°C simulating winter conditions in its natural habitat. Physiological experiments allowed us to time the transition to flowering due to low temperatures, and to compare it to vernalization. We have made use of natural variation, and induced mutants to identify key genes involved in this process, and we provide here data suggesting that an FT gene in M.truncatula is transcriptionally regulated by different environmental cues. Flowering time was found to be correlated with MtFTA and MtFTB expression levels. Mutation in the MtFTA gene showed a late flowering phenotype, while over-expressing MtFTA in Arabidopsis complemented the ft- phenotype. We found that combination of 4°C and 12°C resulted in a synergistic increase in MtFTB expression, while combining 4°C and long photoperiods caused a synergistic increase in MtFTA expression. These results suggest that the two vernalization temperatures work through distinct mechanisms. The early flowering kalil mutant expressed higher levels of MtFTA and not MtFTB suggesting that the KALIL protein represses MtFTA specifically. The desert ecotype Sde Boker flowers earlier in response to short treatments of 8-12oc vernalization and expresses higher levels of MtFTA. This suggests a possible mechanism this desert ecotype developed to flower as fast as possible and finish its growth cycle before the dry period. MtFTA and FT expression are induced by common environmental cues in each species, and expression is repressed under short days. Replacing FT with the MtFTA gene (including regulatory elements) caused high MtFTA expression and early flowering under short days suggesting that the mechanism used to repress flowering under short days has diversified between the two species.The circadian regulated gene, GIGANTEA (GI) encodes a unique protein in Arabidopsis that is involved in flowering mechanism. In this research we characterized how the expression of the M.truncatula GI ortholog is regulated by light and temperature in comparison to its regulation in Arabidopsis. In Arabidopsis GI was found to be involved in temperature compensation to the clock. In addition, GI was found to be involved in mediating the effect of temperature on flowering time. We tested the influence of cold temperature on the MtGI gene in M.truncatula and found correlation between MtGI levels and extended periods of 12°C treatment. MtGI elevation that was found mostly after plants were removed from the cold influence preceded the induction of MtFT expression. This data suggests that MtGI might be involved in 12°C cold perception with respect to flowering in M.truncatula. GI seems to integrate diverse environmental inputs and translates them to the proper physiological and developmental outputs, acting through several different pathways. These research enabled to correlate between temperature and circadian clock in M.truncatula and achieved a better understanding of the flowering mechanism of this species.

Objectives. The major aim of the proposed research was to establish an efficient and reproducible genetic transformation system for Easter lily and gladiolus using either biolistics or Agrobacterium. Transgenic plants containing pathogen-derived genes for virus resistance were to be developed and then tested for virus resistance. The proposal was originally aimed at studying cucumber mosaic virus (CMV) resistance in plants, but studies later included bean yellow mosaic virus (BYMV). Monoclonal antibodies were to be tested to determine their effectiveness in interning with virus infection and vector (aphid) transmission. Those antibodies that effectively interfered with virus infection and transmission were to be cloned as single chain fragments and used for developing transgenic plants with the potential to resist virus infection. Background to the topic. Many flower crops, as lily and gladiolus are propagated vegetatively through bulbs and corms, resulting in virus transmission to the next planting generation. Molecular genetics offers the opportunity of conferring transgene-mediated disease resistance to flower crops that cannot be achieved through classical breeding. CMV infects numerous plant species worldwide including both lilies and gladioli. Major conclusions, solutions and achievements. Results from these for future development of collaborative studies have demonstrated the potential transgenic floral bulb crops for virus resistance. In Israel, an efficient and reproducible genetic transformation system for Easter lily using biolistics was developed. Transient as well as solid expression of GUS reporter gene was demonstrated. Putative transgenic lily plantlets containing the disabled CMV replicase transgene have been developed. The in vitro ability of monoclonal antibodies (mAbs) against CMV to neutralize virus infectivity and block virus transmission by M. persicae were demonstrated. In the US, transgenic Gladiolus plants containing either the BYMV coat protein or antisense coat protein genes have been developed and some lines were found to be virus resistant. Long-term expression of the GUS reporter gene demonstrated that transgene silencing did not occur after three seasons of dormancy in the 28 transgenic Gladiolus plants tested. Selected monoclonal antibody lines have been isolated, cloned as single chain fragments and are being used in developing transgenic plants with CMV resistance. Ornamental crops are multi-million dollar industries in both Israel and the US. The increasing economic value of these floral crops and the increasing ban numerous pesticides makes it more important than ever that alternatives to chemical control of pathogens be studied to determine their possible role in the future. The cooperation resulted in the objectives being promoted at national and international meetings. The cooperation also enabled the technology transfer between the two labs, as well as access to instrumentation and specialization particular to the two labs.

The primary objectives for the US lab included: the characterization of ELF3 transcription and translation; the creation and characterization of various transgenic lines that misexpress ELF3; defining genetic pathways related to ELF3 function regulating floral initiation in Arabidopsis; and the identification of genes that either interact with or are regulated by ELF3. Light quality, photoperiod, and temperature often act as important and, for some species, essential environmental cues for the initiation of flowering. However, there is relatively little information on the molecular mechanisms that directly regulate the developmental pathway from the reception of the inductive light signals to the onset of flowering and the initiation of floral meristems. The ELF3 gene was identified as possibly having a role in light-mediated floral regulation since elj3 mutants not only flower early, but exhibit light-dependent circadian defects. We began investigating ELF3's role in light signalling and flowering by cloning the ELF3 gene. ELF3 is a novel gene only present in plant species; however, there is an ELF3 homolog within Arabidopsis. The Arabidopsis elj3 mutation causes arrhythmic circadian output in continuous light; however, we show conclusively normal circadian function with no alteration of period length in elj3 mutants in dark conditions and that the light-dependent arrhythmia observed in elj3 mutants is pleiotropic on multiple outputs regardless of phase. Plants overexpressing ELF3 have an increased period length in constant light and flower late in long-days; furthermore, etiolated ELF3-overexpressing seedlings exhibit a decreased acute CAB2 response after a red light pulse, whereas the null mutant is hypersensitive to acute induction. This finding suggests that ELF3 negatively regulates light input to both the clock and its outputs. To determine whether ELF3's action is phase dependent, we examined clock resetting by light pulses and constructed phase response curves. Absence of ELF3 activity causes a significant alteration of the phase response curve during the subjective night, and overexpression of ELF3 results in decreased sensitivity to the resetting stimulus, suggesting that ELF3 antagonizes light input to the clock during the night. Indeed, the ELF3 protein interacts with the photoreceptor PHYB in the yeast two-hybrid assay and in vitro. The phase ofELF3 function correlates with its peak expression levels of transcript and protein in the subjective night. ELF3 action, therefore, represents a mechanism by which the oscillator modulates light resetting. Furthermore, flowering time is dependent upon proper expression ofELF3. Scientifically, we've made a big leap in the understanding of the circadian system and how it is coupled so tightly with light reception in terms of period length and clock resetting. Agriculturally, understanding more about the way in which the clock perceives and relays temporal information to pathways such as those involved in the floral transition can lead to increased crop yields by enabling plants to be grown in suboptimal conditions.

Crop maturation is one of the most recognized characteristics of peanut, and it is crucial for adaptability and yield. However, not much is known regarding its genetic and molecular control. The goals of this project were to study the molecular-genetic components that control crop maturation in peanut and identify candidate genes. Crop maturation was studied directly by phenotyping the maturity level or through other component traits such as flowering pattern and branching habit. Six different RIL populations (HH, RR, CC, FNC, TGT and FLIC) were used for the genetic analysis. In total, 14 QTLs were found for maturity level. The phenotypic explanation values ranged in 5.3%-18.6%. Common QTL were found between maturity level and harvest index (in RR and CC populations), branching habit (in HH population), flowering pattern/branching rate (in CC and TGT populations) and pod size (in CC population). Further investigations were done to define genes that control maturity level and the component traits. A map-based cloning approach was used to identify a major candidate gene for branching habit - a novel AhMADS-box gene (AhMADS). AhMADS was mainly expressed in the lateral shoot, the organ in which the difference between branching habit occurs. Sequence alignment analysis found SNPs in AhMADS that cause to exon/intron splicing alterations. Overexpression study of AhMADs-box in tobacco under 35S control revealed one line with a spreading-like lateral shoot indicating that AhMADS may be the causing effect of BH and therefore indirectly controls maturity level. In addition, several candidate genes were defined that may control flowering pattern. An RNA expression study was performed on two parental lines, Tifrunner and GT-C20, identifying four candidate genes in the flowering regulatory pathway that were down-regulated at the mainstem (non-flowering) compared to the first (flowering) shoot, indicating their influence on flowering pattern. Also, another candidate gene was identified, Terminal Flowering 1-like (AhTFL1), which was located within a small segment in chromosome B02. A 1492 bp deletion was found in AhTFL1 that completely co-segregates with the flowering pattern phenotype in the CC population and two independent EMS-mutagenized M2 families. AhTFL1 was significantly less expressed in flowering than non-flowering branches. Finally, a field trial showed that an EMS line (B78) mutagenized in AhTFL1 is ~18% days earlier than the control (Hanoch). In conclusion, our study revealed new insights into the molecular basis for the fundamentally important crop maturity trait in peanut. The results generated new information and materials that will promote informed targeting of peanut idiotypes by indirect selection and genomic breeding approaches.