Thesis (MSc .(Plant Production)) -- University of Limpopo, 2016 / Delayed fruit harvest (DFH) or on-tree-fruit storage is a strategy being considered to extend the harvest season of late maturing ‘Reed’ avocado. However, avocado fruit growth beyond physiological maturity is accompanied by alterations in chemical and physical properties. Thus, the study aimed to investigate the effects of delayed harvest on tree productivity, mineral nutrition and post-harvest quality of late maturing ‘Reed’ avocado and further to evaluate the fruit quality response to varying ripening temperature regimes. As treatments, fruit were harvested early, mid and late in the season, with one month apart from each harvest during 2013 and 2014 seasons. Yield and fruit size were recorded at harvest. During each harvest time, two sets of fruit samples were collected to determine the fruit nutritional content while the second set was cold stored at 5.5°C for 28 days. After storage, fruit were ripened at 16, 21 or 25°C and evaluated for post-harvest disorders, pathological diseases and fruit physico-chemical properties. Yield dropped from 42 to 12 kg/tree from early to late harvest during 2013, while treatments showed no effect during 2014. Furthermore, treatments had no effect on fruit size during both seasons. Phosphorus content decreased by 40 and 23% from early to late harvest time during 2013 and 2014 seasons, respectively. Similar decreasing patterns were observed for K, Ca and Mg content. Zinc content remained constant during 2013; however, mid-season fruit maintained higher zinc levels during 2014 season when compared to early and late harvest time. Protein content was constant for early and mid-season fruit but significantly decreased during the late harvest in both seasons. Moisture content decreased from 74.0 to 65.0% from early to late harvest during both seasons. Starch, oil and ash content were high during late harvest time in both seasons; while crude fibre was high during the mid-harvest time when compared with early and late harvest time. Internal chilling injury increased with maturity and ripening temperature. In both seasons, higher temperatures induced higher anthracnose incidences during early and mid-harvest compared with late harvest time. Similarly, vascular browning was high on fruit ripened at 16°C during early and mid-harvest time but decreased on late harvest fruit during 2013. However, low ripening temperatures induced high incidences of vascular browning during 2014 season. Stem-end rot was high on fruit ripened at 16°C than 21 and 25°C during 2014 season. xvi Physico-chemical quality parameters showed similar behaviour in both seasons. Fruit lightness increased with ripening time regardless of ripening temperature during the early harvest, but remained constant during mid and late harvest. Hue angle (h0) and Chroma (C*) values were slightly reduced during ripening. Fruit ripened at 25°C had the highest respiration rate and reached a climacteric peak earlier (day 2) than fruit ripened at 21 and 16°C (day 4). Fruit firmness and weight loss were high and rapid at 25°C followed by 21 and 16°C regardless of the harvest time. Delayed harvest had no effect on yield and fruit size. Generally, nutritional content of avocado fruit increased with fruit maturity. Furthermore, fruit maturity played a major role in the response of fruit to ripening temperature. Higher temperature enhanced fruit ripening, but was conducive for development of post-harvest diseases. Keywords: Harvesting time, nutrition, yield, fruit size, ripening temperature, post-harvest quality

West Coast fruit cooperatives working together in joint-venture trading companies may well lower the prices of their fruit for export through economies of scale. However, present and future foreign demand for American fruit may constrain any economies of scale that are realized in joint-venture agreements. The major objective of this thesis is to analyze the import demand for fresh American oranges, apples, and grapes of one important buying area, Hong Kong. Two theoretical constructs are used to model the import demand for American oranges, apples, and grapes in Hong Kong. One relies on more traditional assumptions of product homogeneity. The other utilizes the Strotzian utility tree. The resulting models are estimated using Ordinary Least Squares. Four conclusions may be drawn from the estimated models. First, Hong Kong consumers have very elastic responses to changes in the prices of American oranges, apples, and grapes relative to the prices of oranges, apples, and grapes from other sources. Second, this result is especially true when below average demand conditions prevail. Hence, lower prices realized through joint-venture trading companies increase the competitiveness of American fruit at these weaker times. Third, the per capita quantity demanded of American oranges, apples, and grapes will increase as the incomes of Hong Kong's inhabitants rise. Fourth, the statistical problems encountered in the larger models preclude any definite conclusions regarding the price effects of other fruit on the demand for American oranges, apples, and grapes or the price effects which the American fruit may have on each other. / Graduation date: 1986

L’étude du contrôle de l’expression des gènes a été, au cours de ces dernières années, révolutionnée par la découverte des régulations épigénétiques. Parmi les différents acteurs participant à ces régulations se trouvent les protéines du groupe Polycomb (PcG). Ces protéines, initialement découvertes chez la drosophile, sont responsables de la mise en place et du maintien de "marques épigénétiques" au niveau de gènes cibles, qui sont alors réprimés. Les protéines PcG agissent sous forment de trois complexes dinstincts chez les animaux nommés PRC1 (Polycomb Repressive Complex 1), PRC2 (Polycomb Repressive Complex 2) et PhoRC (Pleiohomeotic Repressive Complex); le PRC2 possédant une activité histone méthyltransférase de type H3 K9/27. Chez les plantes, seules trois classes de protéines PcG sont retrouvées: la classe des Enhancer of zeste E(z), des Extra Sex Combs (ESC) et des Supressor of zeste 12 (Su(z)12), formant le complexe PRC2. Leur rôle dans le développement des plantes a été mis en évidence chez Arabidopsis, au niveau du gamétophyte femelle et de la graine, du maintien de l’état végétatif, de l’identité florale et de la vernalisation. Cependant leur implication dans le développement du fruit reste inconnue. Mon travail a permis d'identifier et de caractériser deux gènes PcG de la classe des E(z) de tomate exprimés dans le fruit, nommés SlEZ1 et SlEZ2. Les proteines SlEZ1 et SlEZ2 présentent l’ensemble des domaines caractéristiques des protéines de cette classe et sont localisées dans les noyaux. Les expériences de double hybride révèlent que les protéines SlEZ1 et SlEZ2 sont capables de former des complexes de type PRC2 avec certaines autres protéines PcG de tomate (de type ESC et Su(z)12). Ceci suggère que SlEZ1 et SlEZ2 sont effectivement des protéines fonctionnelles. L’analyse de des profils d’expression des gènes SlEZ1 et SlEZ2 révèle une expression ubiquitaire dans la plante au niveau de l’appareil végétatif, de la fleur et dans le fruit. Cependant, dans la fleur, seul SlEZ1 présente une expression dans les étamines tandis que les ARNm de SlEZ2 sont présent de façon spécifique dans le tissu de transmission du style. Dans le fruit, SlEZ1 est exprimé de façon constante, tandis que SlEZ2 semble faiblement exprimé dans les fruits en cours de mûrissement. Afin d’identifier la fonction de SlEZ1 dans le développement du fruit, des plantes transgéniques sous-exprimant SlEZ1 de façon constitutive ont été générées. Elles présentent une morphologie altérée de la fleur: les étamines sont torsadées et ne forment pas de cône staminal fermé. De plus, une augmentation du nombre moyen de carpelles par fruit est observée. / The control of gene expression has been challenged by the discovery of epigenetic regulation. Among the different factors involved in epigenetic regulations, the Polycomb (PcG) proteins are known to repress gene expression by setting epigenetic marks. The PcG protein, initially discovered in drosophila, act together in three distinct complexes named PRC1 (Polycomb Repressive Complex 1), PRC2 (Polycomb Repressive Complex 2) and PhoRC (Pleiohomeotic Repressive Complex). PRC2 complexes methylate histone H3 on lysines K9/27. In plants, only three classes of PcG protein has been found: the Enhancer of zeste (E(z)) class, the Extra Sex Combs (ESC) class and the Supressor of zeste 12 (Su(z)12) class, which belong to the PRC2. Their function in plant development has been brought to light in Arabidopsis thaliana. They control female gametophyte and seed development, maintain the vegetative development, and are involved in floral identity and vernalization. However, their function in fruit development is still unknown. My work was aimed to identify and characterize two PcG genes, named SlEZ1 and SlEZ2, encoding tomato E(z) class proteins. SlEZ1 and SlEZ2 proteins contain all the five E(z) characteristic domains and are both localized in the nucleus. Furthermore, as double-hybrid experiments reveal that both SlEZ1 and SlEZ2 proteins are able to form PRC2 complexes and interact with PcG proteins of other classes (ESC and Su(z)12 classes), it seems that these proteins are functional. Their expression profiles reveal ubiquitous expression during vegetative development (leaves, buds, stems) and reproductive development (flowers and fruits). However SlEZ1 is specifically expressed in the stamens whereas SlEZ2 shows specific expression in the transmitting tissue of the style. Moreover, their expression during fruit development shows some differences: if SlEZ1 expression is almost constant, SlEZ2 expression decreases during fruit development. In order to indentify SlEZ1 functions in fruit development, transgenic plants underexpressing constitutively SlEZ1 have been generated. These plants present altered flower morphology with twisted stamens and increased carpel number fruits.

La tomate (Solanum lycopsersicum), qui forme un clade monophylétique restreint au sein de la large famille des Solanacées, est utilisée comme modèle pour l’analyse du génome, et le développement du fruit. A ce jour, de nombreux efforts ont été consacrés à l'analyse de la diversité génétique des espèces de tomate. Cependant peu de travaux ont porté sur l'analyse de la diversité épigénétique, alors qu’il est aujourd’hui admis que les processus épigénétiques jouent un rôle essentiel dans la diversité phénotypique. Dans un premier temps, le niveau de méthylation de l'ADN a été comparé dans les feuilles et les fruits de différentes variétés de tomates sauvages et cultivées. Puis la famille des gènes Enhancer of zeste (E (z)) a été analysée. Chez la tomate, cette famille comprend deux gènes fonctionnels ainsi qu’un pseudogène. Finalement la stabilité épigénétique reste un facteur majeur pouvant avoir un impact essentiel sur les stratégies de sélection végétales. En outre nous avons fait une caractérisation fine des différents aspects du développement du fruit et de la maturation. / Tomato (Solanum lycopsersicum) which forms a small monophyletic clade within the large Solanaceae family has been chosen as a model system for studying the Solanaceae genome, fruit development and ripening. At that time, many efforts have been devoted to the analysis of the genetic diversity of tomato species, little work has focused on the analysis epigenetic diversity in this clade, although there is a general agreement that epigenetic processes play essential role in the phenotypic diversity in animal and plant system. As first step, DNA methylation level was analyzed in leaves and fruits of various wild and cultivated tomato species.Additionally, the Enhancer of zest (E(z)) gene family has been analyzed. In tomato, the E(z) family consists in two functional genes (SlEZ1, SlEZ2) and in a pseudogene (SlEZ3). In addition, the epigenetic stability is an important consideration that could have a significant on strategies for crop breading. Finally, we made a fine characterization of the different aspects of fruit development and ripening. / All’interno della grande famiglia delle Solanacee è stato scelto il pomodoro (Solanum lycopsersicum) come sistema modello per studio dello sviluppo e maturazione del frutto. Molti sforzi sono stati fatti per analizzare la diversità genetica delle specie di pomodoro, pochi lavori invece riguardano l’analisi della diversità epigenetica, sebbene ci sia accordo sul fatto che processi epigenetici giochino un ruolo essenziale nella diversità fenotipica dei sistemi animali e vegetali. Inizialmente è stato analizzato il livello di metilazione del DNA in foglie e frutti delle diverse specie di pomodoro selvatico e coltivato. Inoltre, è stata analizzata la famiglia genica Enhancer of Zeste (E (z)). In pomodoro la famiglia E(z) consiste di 2 geni funzionali SlEZ1, SlEZ2 e di uno pseudogene SlEZ3. Inoltre la stabilità epigenetica è importante in quanto può avere un impatto sulle strategie di miglioramento genetico delle specie coltivate. Infine è stata condotta una attenta caratterizzazione dei meccanismi cellulari dello sviluppo del frutto e della sua maturazione.

Le marché mondial des fruits représente des centaines de milliards d’euro par an et l’amélioration de la qualité organoleptique et nutritionnelle des fruits est l’un des principaux objectifs de ces dernières années. Le métabolisme primaire est une cible toute trouvée pour tenter de répondre à ces exigences. En effet c’est lui qui va fournir les briques nécessaires à la croissance et au développement, mais également les composés qui confèrent les valeurs gustatives tels que les sucres et les acides organiques. C’est pourquoi la compréhension de son fonctionnement au cours du développement des fruits est nécessaire. Pour cela le métabolisme primaire a été étudié chez huit espèces de fruits charnus qui diffèrent en termes de durée de développement, de taille de fruit, de famille botanique, de qualité gustative (sucrosité, acidité…), et sujettes ou non à une crise respiratoire au début de la maturation. Des données physiologiques et biochimiques ont été collectées tout au long du développement du fruit, de l’anthèse à la maturité physiologique. La modélisation de la croissance des fruits a permis de standardiser les stades de développement et ainsi d’améliorer la comparaison entre espèces. La composition de la biomasse a ensuite été caractérisée qualitativement et quantitativement par des approches analytiques ciblées et non ciblées mettant en évidence les similitudes et les différences de composition et d’évolution au cours du développement. Des modèles linéaires généralisés combinant la composition et les données de croissance ont été utilisés pour comparer différentes phases de développement du fruit et une analyse discriminante par régression des moindres carrés partiels (PLS-DA) a permis de séparer les fruits climactériques des non climactériques. Dans les deux cas, les composés des parois cellulaires, les protéines et les lipides interviennent dans la différentiation des groupes. Enfin, une étude détaillée du métabolome et de l’activome du fruit a été réalisée chez trois espèces de Solanacées. Elle montre qu’au sein d’une même famille botanique la régulation diffère au cours du développement, notamment au niveau du métabolisme des sucres et de la glycolyse. Ces travaux revisitent le caractère climactérique des fruits, le positionnant bien en amont du déclenchement de la crise respiratoire, et, plus généralement, permettent de mieux comprendre le métabolisme primaire au cours du développement du fruit. / The world fruit market represents hundreds of billions of euros per year and improving the organoleptic and nutritional quality of fruit has been one of the main objectives in recent years. Primary metabolism is a target that can be used to try and meet these requirements. Indeed, it provides the bricks necessary for growth and development but also the compounds that contribute to taste such as sugars and organic acids. Therefore, it is necessary to understand how it operates during fruit development. For this purpose, primary metabolism has been studied in eight species of fleshy fruits that differ in terms of development duration, fruit size, botanical family, taste quality (sweetness, acidity, etc.), and are subject or not to a respiratory crisis at the initiation of ripening. Physiological and biochemical data have been collected throughout the fruit development from anthesis to physiological maturity. Fruit growth modelling allowed standardizing the stages of development and thus improved comparison between species. The composition of biomass was then characterized qualitatively and quantitatively by targeted and non-targeted analytical approaches highlighting similarities and differences in composition and changes during development. Generalized linear models combining composition and growth data were used to compare different phases of fruit development and a discriminant partial least square regression analysis (PLS-DA) was used to separate climacteric and non-climacteric fruits. In both cases, cell wall compounds, proteins and lipids were involved in group differentiation. Finally, a detailed study of the fruit metabolome and activome was performed in three species of Solanaceae. It revealed that within the same botanical family, regulation differs during development, particularly for sugar metabolism and glycolysis. This work revisits the climacteric character of fruits, positioning it long before the onset of the respiratory crisis, and, more generally, provides a better understanding of primary metabolism during fruit development.

Tjia Wai Mui. / Thesis submitted in: July 2002. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 123-140). / Abstracts in English and Chinese. / Abstract (English) --- p.i / Abstract (Chinese) --- p.iii / Acknowledgement --- p.iv / Abbreviations --- p.v / Table of Contents --- p.vi / List of Figures --- p.x / List of Tables --- p.xii / Chapter Chapter One --- Literature Review / Chapter 1.1 --- Introduction --- p.1 / Chapter 1.2 --- Growth of L. edodes --- p.3 / Chapter 1.2.1 --- Life cycle of L. edodes --- p.3 / Chapter 1.2.2 --- Growth parameters of L. edodes --- p.6 / Chapter 1.2.2.1 --- Temperature --- p.6 / Chapter 1.2.2.2 --- Relative humidity --- p.7 / Chapter 1.2.2.3 --- Moisture content in substrate --- p.7 / Chapter 1.2.2.4 --- Light --- p.8 / Chapter 1.2.2.5 --- pH --- p.8 / Chapter 1.3 --- Cultivation of L. edodes --- p.9 / Chapter 1.3.1 --- History and development of artificial cultivation --- p.9 / Chapter 1.3.2 --- Use of forced fruiting --- p.11 / Chapter 1.4 --- Molecular studies of stress on fungi --- p.12 / Chapter 1.4.1 --- Studies of temperature stress in mushroom --- p.12 / Chapter 1.4.2 --- Studies of molecular chaperones in fungi --- p.13 / Chapter 1.4.2.1 --- Role of molecular chaperones --- p.13 / Chapter 1.4.2.2 --- Heat shock protein 70 (Hsp70) and their cochaperones --- p.13 / Chapter 1.4.2.3 --- Other chaperones --- p.15 / Chapter 1.4.2.4 --- Molecular chaperones and development --- p.16 / Chapter 1.5 --- Prospectus --- p.19 / Chapter Chapter Two --- The Effect of Stress on the Growth of L. edodes / Chapter 2.1 --- Introduction --- p.23 / Chapter 2.2 --- Materials and Methods --- p.24 / Chapter 2.2.1 --- Strain and culture conditions --- p.24 / Chapter 2.2.2 --- Stress treatments --- p.24 / Chapter 2.2.3 --- Data collection --- p.25 / Chapter 2.2.4 --- Data analysis --- p.25 / Chapter 2.3 --- Results --- p.27 / Chapter 2.3.1 --- Reliability analysis --- p.27 / Chapter 2.3.2 --- Descriptive statistics --- p.28 / Chapter 2.3.3 --- Independent t-test (ANOVA) --- p.33 / Chapter 2.4 --- Discussion --- p.37 / Chapter Chapter Three --- Sequence Analysis of selected Stress Genes / Chapter 3.1 --- Introduction --- p.39 / Chapter 3.2 --- Materials and Methods --- p.40 / Chapter 3.2.1 --- Isolation of stress genes --- p.40 / Chapter 3.2.1.1 --- Construction of primordial cDNA library --- p.40 / Chapter 3.2.1.2 --- Screening of cDNA clones --- p.40 / Chapter 3.2.2 --- Sequence analyses of stress genes --- p.41 / Chapter 3.2.2.1 --- Amplification and purification of cDNA insert --- p.41 / Chapter 3.2.2.2 --- Full length DNA cycle sequencing --- p.42 / Chapter 3.2.2.3 --- Sequence analyses --- p.43 / Chapter 3.2.3 --- Screening of LeSSA (Inducible HSP70) --- p.45 / Chapter 3.2.3.1 --- PCR screening of LeSSA by degenerate primers and LeSSB specific primers --- p.45 / Chapter 3.2.3.2 --- Screening of LeSSA from cDNA library by hybridization --- p.49 / Chapter 3.3 --- Results --- p.51 / Chapter 3.3.1 --- Sequence analyses --- p.51 / Chapter 3.3.1.1 --- LeSSB --- p.51 / Chapter 3.3.1.2 --- LeMge1 --- p.57 / Chapter 3.3.1.3 --- LeSTI1 --- p.62 / Chapter 3.3.1.4 --- LeTCP1β --- p.69 / Chapter 3.3.1.5 --- LeTCP1γ --- p.74 / Chapter 3.3.2 --- Failure of isolating LeSSA (Inducible HSP70) --- p.80 / Chapter 3.4 --- Discussion --- p.82 / Chapter 3.4.1 --- Sequence analyses --- p.82 / Chapter 3.4.2 --- Screening of LeSSA --- p.84 / Chapter Chapter Four --- Characterization of stress genes upon different stresses / Chapter 4.1 --- Introduction --- p.86 / Chapter 4.2 --- Materials and Methods --- p.87 / Chapter 4.2.1 --- Strain and culture conditions --- p.87 / Chapter 4.2.2 --- Stress treatments --- p.87 / Chapter 4.2.3 --- Isolation of total RNAs --- p.87 / Chapter 4.2.4 --- Reverse transcriptase-polymerase chain reaction (RT-PCR) --- p.88 / Chapter 4.2.4.1 --- Reverse transcription --- p.88 / Chapter 4.2.4.2 --- PCR amplification by specific primers of stress genes --- p.89 / Chapter 4.2.5 --- Northern blot analyses --- p.91 / Chapter 4.2.5.1 --- RNA fractionation by formaldehyde gel electrophoresis --- p.91 / Chapter 4.2.5.2 --- Northern blotting --- p.91 / Chapter 4.2.5.3 --- Preparation of probes --- p.92 / Chapter 4.2.5.4 --- Hybridization and stringency washes --- p.93 / Chapter 4.2.6 --- Isolation of total protein --- p.94 / Chapter 4.2.7 --- Quantification of protein by Bradford method --- p.95 / Chapter 4.2.8 --- Western blot analyses --- p.95 / Chapter 4.2.8.1 --- Sodium dodecyl sulfate ´ؤ polyacrylamide gel electrophoresis (SDS-PAGE) --- p.95 / Chapter 4.2.8.2 --- Western blotting --- p.96 / Chapter 4.2.8.3 --- Immunodetection --- p.98 / Chapter 4.2.8.4 --- ECL detection --- p.98 / Chapter 4.3 --- Results --- p.99 / Chapter 4.3.1 --- Reverse transcriptase-polymerase chain reaction (RT-PCR) --- p.99 / Chapter 4.3.2 --- Northern blot hybridization --- p.106 / Chapter 4.3.2.1 --- Establishing an internal control --- p.106 / Chapter 4.3.2.2 --- Dig-labelling of stress genes --- p.106 / Chapter 4.3.2.3 --- Northern blot hybridizaton of stress genes --- p.106 / Chapter 4.3.3 --- Western blot hybridization --- p.111 / Chapter 4.4 --- Discussions --- p.113 / Chapter Chapter Five --- General Discussions --- p.118 / References --- p.123

Thesis (M.Sc. Agric. (Horticulture)) --University of Limpopo, 2008 / The mineral nutrition of indigenous crop species is not well documented like other known crop species, thus making it difficult for one to know how to plant and maintain the crops. Mmupudu (Mimusops zeyheri), which, happens to be a wild crop, is one of the indigenous trees of interest to the Discipline of Plant Production, University of Limpopo. The current study gives baseline information that will be important in various environmental physiology studies of this plant. Physiological studies will be necessary to assess the importance of “limiting” mineral nutrients in the accumulation of certain mineral nutrients in Mmupudu in relation to its productivity. The experiment was arranged as a 2 x 3 factorial in RCBD, with the first and second factors being time of sampling and location, respectively. The three locations where data were collected were Chuenespoort, Bochum and Sekgosese. In each location, the experiment was replicated 10 times. Data were analyzed using ANOVA and means were separated using the least significant difference test. The two-factor interaction was nonsignificant (P ≥ 0.10) for both pH and electrical conductivity. Soil pH was not affected by time in all three locations suggesting that abscised flowers and fruitlets have no effect on pH. Leaf K experienced an increase of 65% at Chuenespoort and a decrease of soil K after fruiting by 44%. Leaf and soil P decreased after fruiting in all locations as was the case with Cu. Chuenespoort and Sekgosese experienced a decrease in leaf Mn after fruiting while soil Mn decreased in all whereas leaf Mg decreased in all locations. / the National Research Foundation and the Department of Water Affairs and Forestry

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references (leaves 256-277). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph. D.)--University of Hawaii at Manoa, 1995. / Includes bibliographical references (leaves 171-187). / Microfiche. / xix, 187 leaves, bound ill. 29 cm

Thesis (PhD) -- University of Western Sydney, 2001. / "A thesis in fulfillment of the requirements for the degree of Doctor of Philosophy" Submitted February 2001. Bibliography : leaves 240-264.