Many commercially grown apple cultivars have a biennial cropping habit, producing many small fruit in one year and few or none in the following year. The production of fruits is known to inhibit flower initiation for the following year. This undesirable trait is frequently managed by removing (thinning) some flowers or young fruit in years of heavy flowering which improves the size of remaining fruits, but does not reliably improve flowering in the following year. The effect of thinning on flower initiation is not well understood. Two mathematical models are developed describing the relationship between flowering in one year and the next. The first models the effects of thinning on return bloom and attempts to define maximum repeatable flower number. The second models how proximity of growing points may impact biennial bearing and maximum annual flower number. This second model may be useful to advance research into biennial bearing in apple.

Submitted by Mario BC (mario@bc.ufrpe.br) on 2016-05-25T13:03:29Z No. of bitstreams: 1 Morganna Pollynne Nobrega Pinheiro.pdf: 1645144 bytes, checksum: 5febf32ecd170831a3811cfa9b927d78 (MD5) / Made available in DSpace on 2016-05-25T13:03:29Z (GMT). No. of bitstreams: 1 Morganna Pollynne Nobrega Pinheiro.pdf: 1645144 bytes, checksum: 5febf32ecd170831a3811cfa9b927d78 (MD5) Previous issue date: 2015-05-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / A growing number of studies reports the identification and characterization of genes associated with flower bud and the isolation of its regulatory regions. These strands are helping to unravel a number of issues concerning the regulation and cellular interactions, thus generating a great impact on improving various plant species. In cotton (Gossypium hirsutum) these studies have contributed substantially in obtaining of genetically modified GM plants, holders of genes for resistance to herbicides and lepidopteran, and are becoming the possibility of increasing the control efficiency against target pests that act directly in floral structures and / or even enhance the expression of the coloring effect of the fibers. Different techniques are available for functional genomics analysis, among the most adopted is the construction of expressed sequence tags (ESTs) libraries that allows to identify which RNAs are expressed in an organism at a given time. Using this methodology in a previous study, were characterized by in silico analyzes genes involved in reproductive functions of cotton, some of whom expressed in male and female gametophytes. At that moment, from RT-PCR assays and qRT-PCR, six genes (GhASH, GhFIB010, GhGLUC, GhMYB, GhOVU and GhUDP) were investigated for the temporal expression during ontogeny flower bud, at stages 2-4 6-8, 10, 12, 14-16, and 18-20 mm. All of the genes investigated were active in floral buds of different sizes and in different expression levels, however, the highest level observed was 10 mm, except for gene GhASH with the highest expression in 10 to 16 mm. In these stages the cotton bud is in intense cellular activity including reduced cell wall formation of the complete embryonic sac, appearance and degeneration of the antipodes suggesting that these genes that may be involved in the formation and development or ovules, pollen, pollen tube, as well as on fibers. The gene was GhASH which also had the highest level of expression in all stages compared to other genes. Due to the regulation of these genes involved precursor steps, prior to anthesis and possibly runs through the final process of maturation, we proceeded further a study of tissue expression in organs flowering cotton (bracts, sepals, petals, ovules, anthers and fibers with 8, 10 and 18 DPA) to understand the interrelationships of the genes involved in the reproductive phase and its performance during development. It was found that all genes showed equivalent expression with its features, described in the databases. Analyses of gene activity for genes GhASH, GhOVU and GhGLUC proposed performances in training and / or development of all floral organs especially in pollen grains, pollen tube and anthers. For genes involved in fiber GhMYB, GhFIB010, GhUDP expression was observed for all studied growth stage, suggesting that are directly involved in elongation phase of the fibers, this phase has been widely investigated since the length of the cotton fiber is a key feature in determining the quality and yield. Additional studies to functional characterization of promising genes and isolation of their regions upstream become necessary in order to contribute to the progress and molecular breeding of this oilseed. / É crescente o número de pesquisas que reportam a identificação e caracterização de genes associados ao botão floral, bem como no isolamento de suas regiões regulatórias. Estas vertentes vêm auxiliando na elucidação de várias questões relativas à regulação e das interações celulares, gerando assim um grande impacto no melhoramento de várias espécies vegetais. Em algodão (Gossypium hirsutum) estes estudos têm contribuido substancialmente na obtenção de plantas geneticamente modificadas (GM), detentoras de genes para resistência a herbicidas e lepidópteros, e reveste-se na possibilidade de aumentar a eficiência de controle contra pragas alvo que atuam diretamente em estruturas florais e/ou ainda, potencializar o efeito de expressão na coloração das fibras. Diferentes técnicas estão disponíveis para a análise de genômica funcional, entre as mais adotadas está a construção de bibliotecas de curtas sequêcias expressas (ESTs) que permite identificar quais RNAs mensageiros estão sendo expressos num organismo em um determinado momento. Com o uso desta metodologia em estudo anterior, foram caracterizados por análises in silico genes envolvidos em funções reprodutivas do algodoeiro, alguns dos quais expressos nos gametófitos masculino e feminino. Nesse momento, a partir de ensaios de RT-PCR e qRT-PCR, seis genes (GhASH, GhFIB010, GhGLUC, GhMYB, GhOVU e GhUDP) foram investigados quanto à expressão temporal durante a ontogenia do botão floral, nos estádios de 2-4, 6-8, 10, 12, 14-16 e 18-20 mm. Todos os genes investigados apresentaram atividade nos diferentes tamanhos dos botões florais e com níveis diferenciados de expressão, contudo, o maior nível foi observado no tamanho de 10 mm, com exceção do gene GhASH que apresentou maior expressão nos botões de 10 a 16 mm. Nestes estádios o botão encontra-se em atividade celular intensa incluindo redução da parede celular, formação dos sacos embrionários completos, surgimento e degeneração das antípodas, sugerindo que esses genes podem estar envolvidos na formação e ou desenvolvimento de óvulos, grãos de pólen, tubo polínico, como também em fibras. O gene GhASH também apresentou o maior nível de expressão em todos os estádios do botão floral quando comparado aos demais genes. Em função da regulação desses genes envolverem etapas precursoras, que antecedem a antese e que, possivelmente perpassa o processo final de maturação, procedeu-se adicionalmente um estudo de expressão tissular em órgãos floríferos do algodão (brácteas, sépalas, pétalas, óvulos, anteras e fibras com 8, 10 e 18 DPA) de modo a entender as interrelações dos genes envolvidos na fase reprodutiva e sua atuação durante o desenvolvimento. Verificou-se que todos os genes apresentaram expressão equivalente com suas funcionalidades descritas nos bancos de dados. As análises da atividade gênica para os genes GhASH, GhOVU e GhGLUC propuseram atuações na formação e/ou desenvolvimento de todos os órgãos florais sobretudo em grãos de pólen, tubo polínico e anteras. Para os genes envolvidos nas fibras, GhMYB, GhFIB010, GhUDP, a expressão foi observada para todas as três fases fenológicas estudadas, sugerindo assim que estejam envolvidos diretamente na fase de elongação das fibras, fase que tem sido bastante investigada, uma vez que o comprimento das fibras de algodão é uma característica chave de determinação da qualidade e rendimento. Estudos adicionais para caracterização funcional dos genes promissores e isolamento de suas regiões upstream tornam-se necessários a fim de contribuir com os avanços do melhoramento genético e molecular dessa oleaginosa.

Biennial bearing has been investigated longer and more extensively in apple than in any other fruit tree; however, it remains a serious problem in commercial apple production all over the world. Trees that have become biennial flower profusely and carry a heavy crop in the "on" year, and flower sparsely or not at all and carry little or no crop the following year, the "off" year. Fruit in the "on" year tend to be small, poorly colored, and of low quality, while the few fruit in the "off" year are usually too large, become susceptible to physiological disorders, and also are of poor quality. Without intervention, the crops in both the "on" and "off" years are undesirable and uneconomical. The most common method used by commercial apple growers to try to prevent biennial bearing is chemical fruit thinning, which is an "on" year method of removing a part of the crop before it matures on the tree. In general, growers don't do anything in the "off" year to prevent biennial bearing with the exceptions of fertilizing and pruning lightly. In this study, several experiments were conducted with the cultivars "Braeburn", "Golden Delicious", "Ramey York", and "Fuji" in the "off" year to try and suppress FBI and thus prevent a biennial bearing situation in the following year. The first set of experiments studied the effect of whole-tree and partial-tree defoliation on suppressing spur and lateral flowering and fruit set. Flowering and fruit set were suppressed with defoliation in most cases. Defoliation in early July caused the least amount of flowering the following year and in some cases it was zero. As the defoliation timing and severity was delayed, there was less suppression of flowering and fruit set. Ammonium thiosulfate and Endothal increased flowering but decreased fruit set compared to a control. Gramoxone suppressed flowering and fruit set. In another set of experiments, gibberellic acid (GA) treatments were evaluated to suppress FBI in "off" or light crop years. The GA4+7 treatments suppressed return bloom of both spur and lateral flowers more than the GA3 treatments. The effectiveness of GA declined with delayed application. Both GA treatments reduced lateral flowering the most on the basal 1/3 of the shoot. In a four year study, apple trees were thinned to one fruit per flowering cluster every year from 1997 to 2000. Other trees were thinned to zero fruit or two fruit per flowering cluster in alternate years from 1997 to 2000. Trees thinned to one fruit per flowering cluster had moderate flowering and fruit set the following year. Trees thinned to two fruit per flowering cluster had very little to no flowering the following year. Trees thinned to zero fruit per flowering cluster had a "snowball" bloom the following year. Trees that were alternately thinned to two or zero fruit per flowering cluster were in a biennial bearing situation. / Ph. D.

In loquat, apex of a current shoot changes from vegetative to reproductive stage during summer, i.e. under high temperature conditions. Indeed, just before floral bud differentiation, a decline in the growth rate due to high temperature takes place. The aim of this work is to study the role of this 'summer rest period' on the apex transition from vegetative to reproductive stage. For this purpose 1) sprouting of secondary shoots was promoted at different times, removing the main shoot, before, during and after floral bud differentiation occurred and 2) groups of trees were shifted to a greenhouse under average maximum temperature not exceeding 25 ° C during different periods from June to October. Floral bud differentiation was evaluated. LEAFY (LFY), APETALA (AP1), TERMINAL FLOWERING 1 (TFL1) and FLOWERING LOCUS T (FT1) expression and hormonal content in abscisic acid (ABA), gibberellins (GAs), indoleacetic acid (IAA) and cytokinins (CKs) were analyzed in bud collected during the summer. Results suggest that the date of shoot apex removal determining floral bud differentiation of new shoots, so that the percentage of the new reproductive shoots reduced with the delaying of apex removal. On the other hand, maximum average temperature not exceeding 25 ° C prevented floral bud differentiation. Buds of the trees under indoors conditons displayed lower expression of identity floral genes EjLFY and EjAP1 than buds of trees grown in field. On the contrary, the floral repressor EjTFL1 and EjFT1 gene expressed higher in buds of the trees grown indoors. Time-course of ABA decreased in buds of trees grown in field during studied period while in buds of trees under greenhouse conditions displayed a growing trend. Time-course of GAs, IAA and CKs concentrations did not show remarkable differences between buds of trees growing under field and indoors conditions. Accordingly, 1) secondary shoots emerged from mid- August are unfitness to flower and 2) maximum average tempertature 25±1 °C during the summer prevents floral bud differentiation, enhances ABA biosynthesis, reduces EjLFY and EjAP1 expression and enhance EjTFL1 expression in the apex. / El níspero japonés diferencia sus yemas durante el verano, después de un periodo de ralentización del crecimiento vegetativo ligado a las altas temperaturas que se conoce como reposo estival. El objetivo de esta tesis fue estudiar la influencia de la parada estival en la diferenciación floral de esta especie. Para ello se diseñó un experimento en el que se forzó la brotación de brotes anticipados eliminado el ápice principal en diferentes fechas entre julio y septiembre, antes, durante y después de la parada estival. Paralelamente se diseñó otro experimento en el que se cambiaron las condiciones climáticas a grupos de árboles manteniéndolos en un invernadero a una temperatura máxima media de 25 °C durante diferentes periodos de diversa duración. Se evaluó la diferenciación floral y se analizó la expresión de los genes relacionados con la floración LEAFY (LFY), APETALA (AP1), TERMINAL FLOWERING 1 (TFL1) and FLOWERING LOCUS T (FT1) y el contenido hormonal en ácido abscisico (ABA), giberelinas (GAs), ácido indolácetico (AIA) y citoquininas (CKs) en yemas terminales muestreadas a lo largo del verano. Los resultados indican que la fecha de brotación modifica la diferenciación floral de los brotes anticipados siendo el porcentaje de brotes reproductivos inversamente proporcional a la fecha de eliminación del meristemo. Del mismo modo unas condiciones de temperatura máxima no superior a 25 °C impidieron la diferenciación floral. Las yemas de los árboles que estuvieron bajo dichas condiciones mantuvieron unos niveles de expresión de los genes de identidad floral, EjLFY y EjAP1, mucho menor que la de los árboles en condiciones de campo. Por el contrario, la expresión del represor EjTFL1 y del gen EjFT1 fue mayor en los árboles en invernadero. Por otro lado, el contenido endógeno de ABA descendió en los árboles situados en el campo durante el periodo de estudio mientras que en los árboles situados en el invernadero tuvo una evolución ascendente. Las concentraciones de GAs, AIA y CKs no mostraron prácticamente diferencias entre los ápices de los árboles mantenidos en campo y en invernadero. De acuerdo con ello, 1) los brotes anticipados surgidos a partir de mitad de agosto son incapaces de florecer y 2) la ausencia de altas temperaturas del verano promueve la acumulación de ABA, aumenta la expresión del gen represor (EjTFL1) y reduce la expresión de los genes de identidad floral (EjLFY y EjAP1) en yemas de níspero impidiendo su diferenciación floral. / El nispro japonés diferència les seus gemmes durant l'estiu, després d'un període d'alentiment del creixement vegetatiu lligat a les altes temperatures que es coneix com repòs estival. L'objectiu d'aquesta Tesi va ser estudiar la influència de la parada estival en la diferenciació floral d'aquesta espècie. Per a això es va dissenyar un experiment en què es va forçar la aparició dels brots anticipats eliminat l'àpex principal en diferents dates entre juliol i setembre, abans, durant i després de l'aturada estival. Paral·lelament es va dissenyar un altre experiment en què es van canviar les condicions climàtiques a grups d'arbres mantenint-los en un hivernacle a una temperatura màxima mitjana de 25 °C durant diferents períodes de diversa durada. Es va avaluar la diferenciació floral i es va analitzar l'expressió dels gens relacionats amb la floració LEAFY (LFY), APETALA (AP1), TERMINAL FLOWERING 1 (TFL1) and FLOWERING LOCUS T (FT1) i el contingut hormonal en àcid abscísic (ABA) , gibberel·lines (GAs), àcid indolacètic (AIA) i citoquinines (CKs) en gemmes terminals mostrejades al llarg de l'estiu. Els resultats indiquen que la data de brotació modifica la diferenciació floral dels brots anticipats i el percentatge de brots reproductius es inversament proporcional a la data d'eliminació del meristema. De la mateixa manera unes condicions de temperatura màxima no superior a 25 ° C varen impedir la diferenciació floral. Les gemmes dels arbres que van estar sota aquestes condicions van mantenir uns nivells d'expressió dels gens d'identitat floral, EjLFY i EjAP1, molt menor que la dels arbres en condicions de camp. Per contra, l'expressió del repressor EjTFL1 i del gen EjFT1 va ser més gran en els arbres en hivernacle. D'altra banda, el contingut endogen d'ABA va baixar en els arbres situats al camp durant el període d'estudi mentre que en els arbres situats a l'hivernacle va tenir una evolució ascendent. Les concentracions de GAs, AIA i CKS no van mostrar pràcticament diferències entre els àpexs dels arbres mantinguts en camp i en hivernacle. D'acord amb això, 1) els brots anticipats sorgits a partir de meitat d'agost són incapaços de florir i 2) l'absència d'altes temperatures de l'estiu promou l'acumulació d'ABA, augmenta l'expressió del gen repressor (EjTFL1) i redueix l'expressió dels gens d'identitat floral (EjLFY i EjAP1) en gemmes de nispro del Japó impedint la seva diferenciació floral. / García Lorca, AL. (2017). Temperature regulating floral bud differentiation in loquat (Eriobotrya japonica Lindl.). Hormonal and genetic aspects [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/79873 / TESIS

The development of plant flowers represents a complex process controlled by numerous mechanisms. The creation of double homozygous mutant of both β subunits (sometimes also referred to as basic transcription factor 3) of nascent polypeptide associated complex in Arabidopsis thaliana (further referred to as nacβ1 nacβ2) caused quite a strong defective phenotype including abnormal number of flower organs, shorter siliques with a reduced seed set, and inferior pollen germination rate together with a lower ovule targeting efficiency. Previously, NAC complex was described to be formed as a heterodimer composed of an α- and β-subunit, which binds ribosome and acts as a chaperone in Saccharomyces cerevisiae. In plants, NACβ is connected to stress tolerance and to plant development as a transcription regulator. However, little is known of NAC heterodimer function in plants. In this thesis, yeast two hybrid system (Y2H) and bimolecular fluorescence complementation (BiFC) assays were used to verify the NAC heterodimer formation in A. thaliana and to establish any potential interaction preferences between both NACβ paralogues and five NACα paralogues. To deepen the understanding about molecular mechanisms behind the nacβ1 nacβ2 phenotype, flower bud transcriptome of the nacβ1 nacβ2 double homozygous mutants...