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1
Azakoglu, Burak. "Avocado Lovers". Digital Commons at Loyola Marymount University and Loyola Law School, 2019. https://digitalcommons.lmu.edu/etd/789.
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Case, Bonita. "The avocado pear tree". Master's thesis, University of Cape Town, 1999. http://hdl.handle.net/11427/22438.
Testo completoAbstract (sommario):
For twenty years Elsie September has refused to visit her uncle, Hannie, a state patient at Valkenberg mental hospital. At her grandmother's insistence, she almost goes to see him one day, but she only gets as far as the building and cannot bring herself to go inside. Instead, she meets Shaun and, as a relationship develops, Elsie begins to tell him the stories of her childhood. But Elsie's relationship with Shaun is troubled and unbalanced. Before Elsie reaches the point in her narrative where she will explain why she refuses to see her uncle, she and Shaun part acrimoniously and he disappears. Elsie has, by now, become so caught up in the telling of her story that not even Shaun's disappearance can stop her from going back to the day her world changed beneath the sheltering arms of the avocado pear tree.
3
Marques, José Roberto. "'Hass' avocado fruit quality : the role of fruit minerals and rootstocks /". St. Lucia, Qld, 2002. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16748.pdf.
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Mostert, Mathilda Elizabeth. "Characterization of micro-components of avocado oil extracted with supercritical carbon dioxide and their effect on its oxidative stability". Pretoria : [s.n.], 2007. http://upetd.up.ac.za/thesis/available/etd-06062008-132406.
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5
Munzhedzi, Mukondeleli. "Effect of haverst season and ripening duration on the physico-chemical properties of new 'fuerte-type' avocando fruit selections during ripening". Thesis, University of Limpopo, 2016. http://hdl.handle.net/10386/1810.
Testo completoAbstract (sommario):
Thesis (MSc. Agriculture (Horticulture)) -- University of Limpopo, 2016The Agricultural Research Council-Institute for Tropical and Subtropical Crops (ARC-ITSC) is continuously developing new avocado selections, in order for the South African Avocado Industry (SAAI) to remain competitive in various international avocado markets. However, information on the response of some of these selections, including ‘Fuerte 2 and 4’, ‘BL1058’ and ‘H287’ to low temperature storage and ripening physiology, has not been investigated. Thus, the objective of this study was to evaluate the effect of harvest season and ripening duration on the physico-chemical properties of newly developed ‘Fuerte-type’ avocado fruit selections during ripening. ‘Fuerte-type’ avocado fruit were indexed for maturity using moisture content, thereafter harvested and stored at 5.5°C for 28 days during the 2014 and 2015 harvest seasons. The experiment comprised five treatments: control (commercial ‘Fuerte’), ‘Fuerte 2 and 4’, ‘BL1058’ and ‘H287’ arranged as a factorial in a completely randomised design (RCD) with 3 replicates. The treatment factors were: (i) 2 x harvest seasons, (ii) 5 x selections and (iii) 6 x ripening days. After withdrawal from low storage temperature, fruit were ripened at ambient temperature. During ripening, the following physico-chemical properties were evaluated; external chilling injury, electrolyte leakage, mass loss, firmness, respiration rate and peel colour. Results showed that selections and harvest seasons had no significant effect (P=0.668) on the moisture content of the evaluated ‘Fuerte-type’ avocado fruit. After withdrawal from low storage temperature, there was a significant interaction (P˂0.05) between selections and harvest seasons on external chilling injury and electrolyte leakage. Results further showed that external chilling injury correlated with electrolyte leakage during both harvest seasons. Treatment factors had no significant effect (P=0.997) on mass loss. Similarly, treatment factors had no significant effect (P=0.139) on firmness. However, selection ‘H287’ had hard skin with an average firmness of 83.44 densimeter units during ripening in both harvest seasons. Treatment factors were highly significant (P˂0.05) on respiration rate. Respiration rate followed a climacteric pattern and the magnitude of climacteric peak and day of occurrence varied amongst selections during both harvest seasons. Ripening percentage differed significantly (P˂0.05) amongst harvest seasons, selections and ripening days. Treatment factors had no significant effect on lightness (P=0.711), chroma (P=0.378) and hue angle (P=0.536) skin colour parameters,however, variations were recorded as a result of the cold damage black spots. The results indicated that the ‘Fuerte-type’ avocado selections had poor storage qualities. Further studies are required to evaluate physico-chemical properties during low storage temperature and the effect of season, production conditions and maturity level on development of chilling injury. In addition, studies on application of treatments to reduce chilling injury symptoms and analysis of bioactive compounds should be considered for conclusive recommendations. Thereafter, the selections can be planted in different production regions to assess and select the best producing and quality combinations for a given region as part of phase III of the project
Agricultural Sector Education Training Authority (AgriSeta) and National Research Foundation (NRF)
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Giblin, Fiona Rosanna. "Avocado fruit responses to Colletotrichum gloeosporioides /". [St. Lucia, Qld.], 2005. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe19403.pdf.
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Tramberend, Henrik. "Avocado: a distributed virtual environment framework". [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=967442222.
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8
Mandemaker, Andries Jan. "Winter Leaf Yellowing in 'Hass' Avocado". The University of Waikato, 2007. http://hdl.handle.net/10289/2251.
Testo completoAbstract (sommario):
The New Zealand avocado industry is worth $39.7 million in exports of 'Hass' avocados. Crop yields grew steadily from 1996 to 2001 to reach an average of 8.86 tonnes/ha. Since then however, crop yields have remained steady. To increase returns to growers, crop yields must increase. Avocado leaves in New Zealand become yellow in winter and it is hypothesised that chilling, followed by photoinhibition, is leading to photooxidation. Leaf yellowing leads to reduced photosynthetic capacity and early leaf abscission, at a time when carbon fixation and carbohydrate reserves are needed to support developing flowers, subsequent fruit set and vegetative flush, in addition to the existing mature crop. The focus of this research was to determine the underlying causes of yellowing in 'Hass' avocado leaves during winter. It is suspected that it is a result of the creation of free-radical oxygen that causes photooxidation of leaf components under excess light during low temperature conditions, such as experienced on clear winter mornings in the Bay of Plenty. An orchard in Katikati, in the Bay of Plenty, New Zealand was selected has it had a history of leaf yellowing. Two open flow, differential gas exchange measurement systems, The CIRAS-1 and the CMS-400 were used to monitor leaf photosynthetic performance over the course of the 2006 winter, with particular focus on the month of August. Chlorophyll a fluorescence was measured with a Walz Mini-PAM, leaf colour with a Minolta Chroma meter CR-200b and chlorophyll content with Minolta SPAD chlorophyll meter (in addition to traditional extraction techniques). There was conclusive evidence that the cold nights resulted in decreased net photosynthesis over the winter, with the depression starting in May and ending around the middle of August, dates that coincide closely with the period when days with mean temperatures less than 10 C occurred. The decrease in photosynthesis appears to be due to a direct effect on the carbon reduction pathway and in unusual in that full recovery seems to occur at the same time during the day. No photodamage of significance was found and the avocado seems to be highly protected against high light when photosynthesis is inhibited. This investigation found that leaf yellowing is not caused by photodamage following depressed photosynthesis. A new hypothesis is proposed which suggests that leaf yellowing is produced by the re-allocation of nitrogen from leaves during cold weather during flowering. It is suggested that the chilled leaves are seen as unproductive, old or shaded leaves by the plant and nutrient resources are re-allocated away from these leaves. A foliar application of 1% low biuret urea and 0.5% magnesium sulphate is currently used by avocado growers to restore leaf colour in leaves that have become yellow over winter. An experiment was carried out on yellowed leaves on 23rd August 2006 to determine the effectiveness of the treatment. This study concluded that the treatment was able to restore some leaf colour, but had no effect on leaf photosynthetic function.
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Forero, María Paulina. "Storage life enhancement of avocado fruits". Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=18276.
Testo completoAbstract (sommario):
Avocado Fruit (Persea americana Mill. Var. Hass) is one of the most perishable commodities available in the market. It has a very high rate of postharvest respiration, limited shelf life and has special unique characteristics of ripening. In the first part of this study, a silicon membrane system was used for the storage of ‘Hass’ avocado fruits. The silicone membrane system is an efficient method for attaining and maintaining modified atmosphere (MA) in experimental storage chambers. The storage was performed in small sealed experimental chambers fitted with silicon membrane windows. The areas of the windows were calculated in order to achieve 3% oxygen assuming 30, 50, and 70% reduction of the respiration rate due to the effect of the modified atmosphere on the products’ metabolic activity. Fruit stored at regular atmosphere (control) was kept under the same temperature (7°C) and relative humidity (90%) as those stored with silicon membrane system. The gas concentration in the chambers was analyzed using a gas chromatograph. The respiration rate was measured at storage (7°C) and ripening (15°C) temperatures. The effect of sulphur dioxide treatment on ‘Hass’ avocado fruit stored in the silicon membrane system was also evaluated. Fruit quality before storage, after storage and after ripening was evaluated through physiological assessments. Fruit stored under the silicon membrane system remained in an excellent condition for 47 days. Following this period avocados ripened normally in a course of 4-10 days at 15°C and regular atmosphere. After ripening, the fruit did not show any apparent pysiological deterioration or damage, neither development of undesirable organoleptic changes. The chambers with the small membrane area reached stable gas concentration in 6 days, the chambers with the large membrane area never reached steady gas concentration to the desired levels; while the chambers with medium membrane area reached steady gas concentration in 15L’Avocat est un des fruits les plus périssables disponible sur le marché. Il a un taux de respiration post-récolte très élevé, une durée de vie limitée sur les étagères et possède des caractéristiques spéciales et uniques de véraison. Dans la première partie de cette étude, une membrane de silicone a été utilisée pour conserver les fruits d’avocat de la variété Hass. La conservation a été effectuée dans petites chambres expérimentales scellés avec des ouvertures cuovertes par membranes de silicone. La surface des fenêtres ont étés dimensionnées afin d’atteindre 3% d’oxygène assumant 30, 50 et 70% de réduction du taux de respiration dû à l’effet de l’atmosphère modifiée sur le métabolisme du produit. Les fruits conservés dans une atmosphère non modifiée, le groupe de contrôle, étaient conservés sous la même température, soit 7°C, et une humidité relative de 90% comme ceux conservés avec le système à membrane de silicone. La concentration interne des gaz de la chambre a été analysée par chromatographie en phase gazeuse. Le taux de respiration a été mesuré à la température de conservation (7°C) et de véraison (15°C). L’effet d’un traitement au dioxyde de soufre sur les fruits d’avocat de la variété Hass conservés à l’aide du système a membrane de silicone a aussi été évalué. La qualité des fruits avant entreposage, après entreposage et après véraison a été évaluée par échantillonnage. Les fruits entreposés avec le système à membrane de silicone ont conservés une excellente condition pour 47 jours. Après cette période les fruits d’avocats maturent normalement dans une période de 4 à 10 jours à une température de 15°C dans une atmosphère normale. Après véraison les fruits n’ont aucun signe de détérioration physiologique ou dommage et n’ont plus de développement organoleptique indésirable. La chambre avec les membranes de petite surface a atteint l
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Shikwambana, Kingsly. "Effect of harvest time, post-harvest storage and ripening temperature on fruit quality of reed avocado cultivar". Thesis, University of Limpopo, 2016. http://hdl.handle.net/10386/2049.
Testo completoAbstract (sommario):
Thesis (M. Sc. (Agriculture, Horticulture)) --University of Limpopo, 2016‘Reed’ avocado is a late season cultivar introduced to South Africa from California. The cultivar has shown good adaptation and produces quality fruit with export potential. Its pre-harvest adaptation and production aspects have been researched and documented. However, the effect of harvest time, post-harvest storage and ripening temperature has not been comprehensively studied on this newly introduced ‘Reed’ avocado cultivar. Therefore, the aim of this work was to investigate the effect of different harvest time, post-harvest storage and ripening temperature on the quality of late season ‘Reed’ avocado fruit. Matured ‘Reed’ avocado fruit were harvested based on moisture content indexing in December (2015) and January (2016). The experiment was carried out in a factorial, arranged in a completely randomised design (CRD) with three replicates. Treatment factors were: 2 x harvest time (mid-and late), 2 x post-harvest storage (2.0 and 5.5°C), 3 x ripening temperature (16, 21 and 25°C) and 5 x ripening day (0, 2, 4, 6 and 8). Fruit were stored at 2.0 and 5.5°C for 28 days, thereafter, ripened at 16, 21 and 25°C until fully ripe. During ripening, fruit were evaluated for weight loss, skin colour, firmness, respiration rate, physiological and pathological disorders. Mid-harvest fruit had higher moisture content when compared with late harvest fruit. However, harvest time, post-harvest storage, ripening temperature and ripening time (days) significantly influenced fruit weight loss, firmness, respiration rate, ripening percentage of ‘Reed’ avocado fruit during ripening. Moreover, fruit firmness decreased faster at higher temperatures (25 and 21°C) with fruit ripening within 4 and 6 days, respectively. In addition, ripening at a lower temperature (16°C) was slower with fruit fully ripened within 8 days after withdrawal from cold storage at both harvest times. ‘Reed’ avocado fruit respiration rate followed a climacteric pattern, however, significantly higher rate at higher temperature (25°C) when compared with lower temperature (16°C) after withdrawal from cold storage during both harvest times. Interestingly, mid-harvest fruit showed high electrolyte damage after withdrawal from 2.0°C when compared with late harvest fruit at the same temperature. Furthermore, mid-harvest fruit stored at 2.0ºC and ripened at 21°C showed higher chilling injury when compared with fruit ripened at 16 and 25°C. High electrolyte leakage positively correlated (R2 = 0.242) with high chilling damage for xiv mid-harvest fruit stored 5.5°C. Treatment factors had a significant effect (P < 0.05) on lightness (L *) and hue angle (h ) but no significant effect (P > 0.05) on chroma (C *) and eye colour of ‘Reed’ avocado fruit during ripening, irrespective of harvest time. Overall results showed a visual change in ‘Reed’ avocado skin colour, with eye colour changing from green to bright yellow. Furthermore, late harvest fruit showed high post-harvest pathological diseases after removal from high temperature (5.5°C) when compared with mid-harvest fruit stored at low storage temperature (2.0°C). Ripening at a higher temperature (21 and 25°C) resulted in higher incidence of stem-end rot and body rot when compared with lower temperature (16°C) for both harvest times. Late harvest fruit showed a higher incidence of vascular browning at higher ripening temperatures (21 and 25°C) when compared with lower temperature (16°C) after withdrawal from cold storage. Moreover, overall results showed that harvest time, post-harvest storage and the ripening temperature had a profound influence on the quality of ‘Reed’ avocado fruit. In conclusion, ‘Reed’ avocado fruit can be harvested during mid- or late season and stored at recommended low temperature (2.0ºC); and thereafter, ripened at either 16 or 21ºC. In addition, future studies should focus on identifying pre-harvest practices that promote higher post-harvest fruit quality for ‘Reed’ avocado fruit under South African production environment. Keywords: ‘Reed’ avocado fruit; firmness; electrolyte leakage; respiration rate; stem-end rot; body rot; vascular browning
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Kilaru, Aruna. "Unlocking the Secrets of Avocado Oil Biosynthesis". Digital Commons @ East Tennessee State University, 2013. https://dc.etsu.edu/etsu-works/4811.
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Kilaru, Aruna, Xia Chao, Keithanne Mockaitis e John Ohlrogge. "Unlocking the Secrets of Avocado Oil Biosynthesis". Digital Commons @ East Tennessee State University, 2013. https://dc.etsu.edu/etsu-works/4780.
Testo completoAbstract (sommario):
Avocado is an economically important crop with ~ 60-70 % oil, by dry weight, in its fruit mesocarp tissue. The steady increase in global demand for avocado (9% per year) has driven interest to identify the biochemical and molecular factors that regulate its triacylglycerol (TAG, oil) biosynthesis. Using 454- and Illumina-based RNA-Seq approaches, we examined the transcriptional basis for TAG biosynthesis in developing mesocarp of avocado. Deep transcriptional profiling data allowed us to identify several transcripts that were differentially represented between the early and late developmental stages of mesocarp. Further analysis of the transcriptome, during oil accumulation, revealed an increased expression of genes mostly associated with fatty acid biosynthesis in plastid but not that of TAG assembly in the endoplasmic reticulum. This pattern of expression was similar to that previously observed in other seed and non-seed tissues. Moreover, WRINKLED1 transcription factor, a regulatory element associated with oil biosynthesis in seed and non-seed tissues of monocot and dicot plants, was identified in avocado as well. Our studies point to distinctive modes of regulation of fatty acid biosynthesis and TAG assembly that are conserved in both seed and non-seed oil-rich plants.
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Kilaru, Aruna. "Changes in Avocado Transcriptome During Fruit Maturation". Digital Commons @ East Tennessee State University, 2014. https://dc.etsu.edu/etsu-works/4774.
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Fiedler, Jan. "Taxonomisch-systematische Untersuchungen an Avocado (Persea americana spp.) mit Hilfe molekularer Marker /". Stuttgart : Grauer, 2000. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=009152499&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Thorp, T. Grant. "Study of modular growth in avocado (Persea americana Mill.) /". Title page, contents and abstract only, 1992. http://web4.library.adelaide.edu.au/theses/09PH/09pht517.pdf.
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Maftoon, Azad Neda. "Evaluation of edible films and coatings for extending the postharvest shelf life of avocado". Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=102678.
Testo completoAbstract (sommario):
The focus of this thesis is to develop pectin-based edible films for application of fruits and vegetables to extend their post harvest shelf life. Preliminary research demonstrated that edible coatings could effectively extend the shelf life of based avocado and peach. The respiration rate, moisture loss, firmness, chemical parameters and color changed in a lower rate in coated fruits as compared with the control. Pectin-based film formulations were then evaluated to identify the proper type and concentration of pectin, lipids and plasticizers in the film. The effects of pectin, beeswax and sorbitol concentration on water vapor permeability, mechanical properties and opacity of the films were then evaluated using response surface methodology to identify appropriate levels of different components. Results of studies on film structure revealed that water vapor permeability increased by pectin and sorbitol concentration and was decreased by beeswax concentration. Mechanical properties were mainly affected by pectin and sorbitol concentration. Beeswax was the most influential factor that affected opacity which increased with increasing beeswax concentration.In order to successfully employ these films, their adsorption behavior, thermal and thermomechanical properties were evaluated as a function of moisture content and sorbitol concentration. The adsorption behavior was strongly influenced by sorbitol concentration. Moisture content and sorbitol concentration increased the films elongation at break, but decreased tensile strength, modulus of elasticity and Tg, and increased water vapor permeability of the films. Finally, avocado was coated with a pectin-based film and the associated quality changes were evaluated during storage. From storage studies, kinetic parameters (rate constants) and activation energy were quantified to help model the quality changes in avocado quality as function of storage temperature and time. Pectin-based coating resulted in slowing down the rate of quality changes in avocado at each storage temperature. In general, most changes were well described by some form of zero or first order rate. Temperature sensitivity of rate constant was adequately described by the Arrhenius model.
A hyperspectral imaging technique was also used to gather additional tools for following quality changes associated with stored avocados. Artificial neural network (ANN) concepts were evaluated as alternated models for predicting quality changes in coated and non-coated avocados during storage at different temperature. Modeling of quality changes in avocado indicated that compared to conventional mathematical models, ANN has more feasibility to predict of these changes. Models developed for firmness, weight loss and total color difference had better fitness than respiration rate.
Finally, the effect of coating on disease severity and different properties of avocados infected by Lasiodiplodia theobromae was studied. The coated fruits demonstrated slower rate of disease progress, respiration rate, softening and color changes. Respiration rate, firmness and color parameters were sensitive to coating and disease severity, and thus these parameters could successfully used to predict fruit quality from disease in coated and uncoated avocados.
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Kritzinger, Madeleine. "Evaluation of hot water and hot air heat shock treatments on South African avocados to minimise the occurrence of chilling injury". Thesis, Stellenbosch : Stellenbosch University, 2002. http://hdl.handle.net/10019.1/52835.
Testo completoAbstract (sommario):
Thesis (MSc Food Sc)--Stellenbosch University, 2002.ENGLISH ABSTRACT: The South African avocado fruit industry is export driven and the successful storage of fruits for extended periods is, therefore, essential. It was recorded that 7.7 million cartons were exported during the 1995 season. The shipping of the avocados takes approximately 15 days and the fruits are being stored at low temperatures to minimise the possibility of fruits softening. Unfortunately low temperature storage results in chilling injury. A possible method to increase avocado resistance to chilling injury is to administer a heat shock treatment. In this way the fruits are protected from chilling injury by inducing the formation of so-called heat-shock proteins which render the cell membranes more resistant to chilling injury. The objective of this study was to evaluate different heat shock treatment protocols as a method of preventing or minimising chilling injury and to extend the shelf-life of avocado fruits while exporting at the lowest possible temperature. Examining the effect of different temperatures and exposure times on the quality of the different avocado cultivars pursued this. The exterior chilling injury on each fruit was quantified and the firmness and internal quality parameters evaluated. A total of 32 Experimental Studies were conducted. The results showed that the Hot Water Heat shock Treatment (HWHST) worked effectively for the South African 'Fuerte' cultivar between 40° and 42°C for exposure times of between 20 and 30 min. The 'Edranol' cultivar also showed promising results between 40° and 42°C for exposure time of between 8 and 22 min. The HWHST was not effective on the South African 'Hass' cultivar. The 'Ryan' cultivar with its thick skin made this cultivar less susceptible to chilling injury and therefore HWHST would be unnecessary. The 'Pinkerton' cultivar had a lot of factors that influenced the results. Therefore, more research needed to be done on the 'Pinkerton' cultivar, before any conclusions could be obtained from this cultivar, although it showed potential. Hot air treatment worked fairly well, but unfortunately the long exposure time needed made this treatment unpractical. Throughout the whole study the importance of maturity surfaced as a major role in all the aspects of post harvest quality.
AFRIKAANSE OPSOMMING: Die Suid-Afrikaanse avokado vrugtebedryf is hoofsaaklik gerig op die uitvoermark en daarom is dit belangrik dat die vrugte vir 'n bepaalde tyd suksesvolopgeberg kan word. Die sensus opname gedurende die 1995 seisoen het getoon dat 7.7 miljoen bokse avokados uitgevoer is. Die avokados word vir ongeveer 15 dae per boot vervoer, wat kan lei tot vrugte wat sag word. Om dit te verhoed, word die vrugte by lae temperature opgeberg. Ongelukkig veroorsaak lae opbergingstemperature koueskade. 'n Moontlike metode om avokados te beskerm teen lae temperature en koueskade te verminder, is om 'n hitteskok behandeling toe te pas. Op hierdie manier word die vrugte beskerm teen koueskade deur die vorming van sogenaamde hitteskok proteïene wat die selwande meer bestand maak teen koueskade. Die doel van hierdie studie was om die verskillende hitteskok behandelings protokols te evalueer as 'n metode van beskerming of vermindering van koueskade en om sodoende die rakleeftyd van avocados te verleng as die vrugte by lae temperature uitgevoer word. Eksperimente is uitgevoer om die effek van verskillende temperature en blootstellingstye op die kwaliteit van die verskillende avokado kultivars te bepaal. Die koueskade op die oppervlakte van elke vrug is bepaal en die fermheid en interne kwaliteit parameters is geëvalueer. In totaal is daar altesaam 32 Eksperimentele Studies gedoen. Die resultate het gewys dat die Warm Water Hitteskok Behandeling (WWHB) effektief was op die Suid-Afrikaanse 'Fuerte' kultivar by temperature tussen 40° en 42°C en by blootstellingstye van tussen 20 en 30 min. Belowende resultate is ook met die 'Edranol' kultivar by temperature tussen 40° en 42°C met blootstellingtye van tussen 8 en 22 min behaal. Die WWHB was oneffektief vir die Suid-Afrikaanse 'Hass' kultivar. Die 'Ryan' kultivar se dik skil het hierdie kultivar minder vatbaar gemaak vir koueskade en daarom was 'n WWHB onnodig gewees. By die 'Pinkerton' kultivar kon daar nog nie 'n gevolgtrekking gemaak word nie, aangesien daar nog baie faktore is wat ondersoek moet word, alhoewel die kultivar baie potentiaal getoon het. Warm lug behandeling het potensiaal gehad, maar die lang blootstellingstye het hierdie behandeling onprakties gemaak. Gedurende die hele studie is daar klem gelê op die rypheisgraad van die vrugte wat na vore gekom het as 'n belangrike faktor wat 'n hoofrol speel in al die aspekte van die na-oes kwaliteit.
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Pearce, Matthew L. "The membrane bound phosphatidic add phosphatase from avocado". Thesis, Durham University, 1997. http://etheses.dur.ac.uk/5071/.
Testo completoAbstract (sommario):
Phosphatidate Phosphatase (EC 3.1.3.4) is an important enzyme in plant lipid metabolism as it lies at a theoretical branchpoint between phospholipid and triacylglycerol biosyntheses. Since it's identification in 1955, it has received very little attention in plant lipid research. Previous studies reported in the literature have been limited to the use of crude plant cell extracts, making an accurate evaluation of the data difficult. The enzyme was characterised and purified to homogeneity from the microsomes of maturing avocado fruit, for the first time from any plant source. The novel procedure utilised detergent solubilisation in CHAPS, followed by anion exchange and Affi-Gel Blue chromatography, ammonium sulphate precipitation and Phenyl Superose chromatography. The enzyme had a subunit molecular mass, as determined by SDS-PAGE of 49kDa. Gel filtration studies revealed it was monomeric. Enzyme activity had a pH optimum of 6.0, was insensitive to N- ethylmaleimide and was stimulated by Mg(^2+). The homogenous enzyme was examined for the ability to hydrolyse sn-1,2- dioleoylglycerol-3-phosphate(PA), sn-1 -oleoylglycerol-3 -phosphate(LPA), sn-2- oleoylglycerol-3-phosphate, ceramide-1-phosphate and p-nitrophenylphosphate. All substrates were used, but the apparent V(_MAX) values for PA and LPA were considerably higher than the other substrates tested. The Michaelis-Menten kinetic model of enzyme catalysis was found to be inappropriate as the surface active enzyme was shown to be dependent on the bulk and surface concentration of the substrate in Triton X-100 mixed micelles. The surface dilution kinetic model was used to study PA and LPA hydrolysis. LPA was a better substrate and was also a potent competitive inhibitor of PA hydrolysis. Considering the specificities of the other enzymes in triacylglycerol biosynthesis, this premature dephosphorylation of LPA would prevent triacylglycerol formation. These findings possibly indicate that strict metabolic channelling is in operation with very low steady state concentrations of LPA with respect to PA, thus preventing any interaction with LPA in vivo.
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Rahman, Md Mahbubar, Jay Shockey e Aruna Kilaru. "Characterization of Select Avocado Acyltransferases by Transient Expression". Digital Commons @ East Tennessee State University, 2018. https://dc.etsu.edu/etsu-works/4814.
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Rahman, Md Mahbubar, Jay Shockey e Aruna Kilaru. "Unlocking the Mystery of Oil Biosynthesis in Avocado". Digital Commons @ East Tennessee State University, 2016. https://dc.etsu.edu/etsu-works/4839.
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Ampuero, Villafuerte Silvia, Ortiz Adolfo Edwin Espinoza e De La Cruz Roxana Betzabe Iparraguirre. "Plan de negocio: Agroexportadora SRA Avocado Export S.A.C". Master's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2020. http://hdl.handle.net/10757/653388.
Testo completoAbstract (sommario):
La presente investigación tiene por finalidad elaborar el Plan de Negocios de Agroexportadora de Paltas Hass para el mercado europeo, específicamente de Holanda, y para ello se desarrolla la línea de Negocio de la empresa “SRA Avocado Export S.A” que, mediante la asociatividad con la ONG CEDEP y los agricultores de valles interandinos en Lucanas (Ayacucho) y de la costa en Palpa e Ica (Ica), se lograría ofrecer productos de alta calidad y en volúmenes suficientes.
La Justificación e importancia del Plan de Negocios que se propone, se considera viable por 04 razones fundamentales: (i) porque el mercado de la palta de exportación tiene bastante potencial de crecimiento y el Perú viene ocupando los primeros lugares en producción y exportación; (ii) la gran demanda del producto por el descubrimiento de cualidades medicinales y culinarias, tanto nacional como internacional; (iii) experiencia institucional de la ONG CEDEP en manejo del cultivo paltas de exportación y su comercialización que garantizara la calidad del fruto; y (iv) y seguir apoyando a poblaciones rurales en situación de pobreza.
Finalmente, los objetivos serán reflejados en el Plan de Negocio, detallando las estrategias, planes y los costos asociados a estos para poder establecer los Estados Financieros del Proyecto de “SRA Avocado”. Conocidas estas cifras, nos permitirá analizar los indicadores de rentabilidad, endeudamiento, liquidez y flujos de efectivo del proyecto. Los factores financieros centrales que acreditan la viabilidad del negocio son el Valor Actual del Proyecto (VAN) que asciende a USD 352,304 y la Tasa Interna de Retorno (TIR) de 55.1%, los cuales nos permiten asegurar que es un proyecto viable financieramente.
El plan de negocios servirá como una guía para agricultores e inversionistas, quienes son finalmente los que por medio de un trabajo asociativo lograrían posicionar el producto en el mercado objetivo, y sacar provecho de lo que el producto puede ofrecer al país y a la empresa privada.The purpose of this research is to prepare the Hass Avocado Agro-exporter Business Plan for the European market, specifically the Netherlands, and for this the business line of the company “SRA Avocado Export SA” is developed which, through association with the NGO CEDEP and the farmers of inter-Andean valleys in Lucanas (Ayacucho) and of the coast in Palpa and Ica (Ica), it would be possible to offer high quality products and in sufficient volumes. The Justification and importance of the proposed Business Plan is considered viable for 04 fundamental reasons: (i) because the avocado market for export has enough growth potential and Peru has been occupying the first places in production and export; (ii) the great demand for the product due to the discovery of medicinal and culinary qualities, both nationally and internationally; (iii) institutional experience of the NGO CEDEP in managing the cultivation of avocados for export and their commercialization that will guarantee the quality of the fruit; and (iv) and continue supporting rural populations living in poverty. Finally, the objectives will be reflected in the Business Plan, they buy the strategies, plans and costs associated with these in order to establish the Financial Statements of the "SRA Avocado" Project. Once these are known, they will analyze the indicators of profitability, indebtedness, liquidity and cash flows of the project. The central financial factors that prove the viability of the business are the Present Value of the Project (NPV) which amounts to USD 352,304 and the Internal Rate of Return (IRR) of 55.1%, which allow us to ensure that it is a financially viable project. The business plan will serve as a guide for farmers and investors, who are ultimately the ones who, through associative work, would be able to position the product in the target market, and take advantage of what the product can offer the country and the private company.
Trabajo de investigación
22
Bhatia, Shina. "In Silico Structural Analyses of Avocado WRINKLED Orthologs". Digital Commons @ East Tennessee State University, 2019. https://dc.etsu.edu/etd/3586.
Testo completoAbstract (sommario):
Transcription factor Wrinkled (WRI) 1 is associated with triacylglycerol (TAG) biosynthesis and accumulation in plant tissues. In avocado (Persea americana), a basal angiosperm, four WRI orthologs (1-4) were identified by transcriptome studies and the gene expression of WRI1, 2 and 3 was associated with TAG accumulation in mesocarp tissue. Therefore, it is hypothesized that putative PaWRI1, 2 and 3 but not PaWRI4 are responsible for TAG synthesis in non-seed tissues. To this extent, various in silico analyses were performed to identify similarities and distinct features of putative WRI genes in basal angiosperm relative to maize and Arabidopsis, a monocot and dicot respectively. Predicted structural comparison of these orthologs is expected to reveal the distinct features of avocado WRI paralogs that are associated with the regulation of oil biosynthesis in non-seed tissues.
23
Holtz, Daniel. "Evaluation and design of a 20-acre avocado orchard". Click here to view, 2010. http://digitalcommons.calpoly.edu/braesp/2/.
Testo completoAbstract (sommario):
Thesis (B.S.)--California Polytechnic State University, 2010.Project advisor: Charles Burt. Title from PDF title page; viewed on Apr. 19, 2010. Includes bibliographical references. Also available on microfiche.
24
Donetti, Manuela. "Postharvest biochemical and physiological characterisation of imported avocado fruit". Thesis, Cranfield University, 2011. http://dspace.lib.cranfield.ac.uk/handle/1826/7672.
Testo completoAbstract (sommario):
Difficulties in controlling and forecasting avocado fruit ripening and the highly perishable nature of the crop once harvested, are the major causes of concern for avocado traders. In particular, the simultaneous presence of many suppliers may account for increased fruit variability during ripening. Avocado is a climacteric fruit with consistent ethylene production after harvest which is also related to high perishability. However, the mechanisms regulating ethylene biosynthesis and mesocarp softening are not completely understood. In order to study such effects, avocado fruit from different growing areas and harvested at various maturity stages, were investigated and the biochemical and physiological changes during ripening at both 18 and 23°C were studied. Mesocarp softening and fatty acid content discriminated fruit maturity and growing area, respectively, whereas C7 sugars (D-mannoheptulose and perseitol) discriminated length of fruit shelf life. For the first time, oleic acid content presents in the oil mesocarp was found to depend on fruit sources making of this a suitable indicator of avocado fruit growing area. In contrast, sugar content declined along fruit maturity and ripening. In particular the mannoheptulose presents in avocado mesocarp might be use to estimate avocado fruit shelf life. Indeed, fruit harvested late in season were found to have a lower C7 content than earlier harvest fruit and a faster softening, regardless fruit source. However, sugars content changed between growing area, thus a general C7 threshold defining fruit storability seems to be not definable. Furthermore, other possible indicators of fruit maturity and/or ripening stage have been searched in the cell wall constituents of avocado mesocarp. Thus, the structural carbohydrates profile of avocado mesocarp investigated with a new immunological method changed during ripening and harvest time (early and late season), suggesting a possible effect of cell wall composition on fruit ripening regulation. Also, the possible use of ethylene application in reducing the high heterogeneity noted on imported fruit from South Africa was also evaluated through different consignments. Results showed ethylene efficacy changed depending on harvest time and fruit dimension with less efficacy of the treatment on fruit harvested at the end of the season and characterised by smaller size.One of the most commercialized avocado cultivars, Hass, is peculiar in that its skin colour changes from green to deep purple as ripening progresses. The most common ripening indicator of avocado fruit is the mesocarp firmness and the destructive nature of this evaluation increases losses in the avocado industry. The availability of a non-destructive indicator of fruit ripening represents an important advantage for avocado consumers and importers. Thus, the possible relationship between mesocarp softening, skin colour were objectively evaluated (C*, L*, and H°), and the main pigment, cyanidin 3-O-glucoside, was investigated. Cyanidin 3-Oglucoside was confirmed to be the main anthocyanin present in avocado cv. Hass peel, regardless of preharvest factors. However, differences in its content were noted between shelf life temperatures. A higher relationship between hue angle and firmness was detected in late harvest fruit, whereas no correlation was found between anthocyanin content and firmness. Avocado skin is also involved in defence mechanisms due to the presence of antifungal and phenolic compounds. These phenolic compounds represent a natural protection against pathogenic infections and seem to be down regulated during ripening. The main phenolics were identified and quantified, using a new analytical method which was validated and optimised. Epicatechin, chlorogenic acid and procyanidin B2 were found to be present in the skin tissue and quantified using this assay and found to vary during shelf life and seasons. Although phenolics were present in minor amounts, in avocado pulp they are involved in mesocarp discoloration incidence, and therefore with fruit postharvest quality. Due to a lack of information, a new straightforward method for the identification and quantification of the main phenolics present in avocado mesocarp was developed. Finally, a commercial trial was undertaken to ensure that the results obtained in the laboratory can be reproduced in the market place. In conclusion, postharvest markers can define avocado fruit maturity and growing area and give guidelines in the control of avocado shelf life. Moreover, new methods for the investigation of the phenolic profiles (peel and mesocarp) and the characterisation of cell wall structures can be further tools in the management of avocado fruit postharvest quality.
25
Bhatia, Shina, Mahbubur Md Rahman e Aruna Kilaru. "Functional Validation of Wrinkled Orthologs in Avocado Oil Biosynthesis". Digital Commons @ East Tennessee State University, 2017. https://dc.etsu.edu/etsu-works/4822.
Testo completoAbstract (sommario):
Triacylglycerol (TAG) is a class of lipid molecules composed of three fatty acyl chains esterified to a glycerol backbone. In plants, TAG is synthesized in various tissues and serves as a carbon and energy source. Oil biosynthesis is well understood in oilseeds however how plants store oil in non-seed tissue is yet to be determined. In Avocado (Persea americana), a basal angiosperm, TAG is exclusively accumulated in mesocarp tissue and therefore is emerging as a model system to uncover underlying mechanisms of TAG biosynthesis in tissues other than seed. The mesocarp of Avocado fruit contains ~60-70% of oil by dry weight. Recent transcriptome studies revealed that the TAG biosynthesis is transcriptionally regulated in non-seed tissues. In seed tissues, TAG biosynthesis is regulated by many seed maturation factors directly or indirectly through downstream transcription factor WRINKLED1 (WRI1). Transcriptome studies revealed that in addition to ortholog of WRI1, orthologs for WRI2 and WRI3 were also highly expressed in avocado mesocarp during the period of oil accumulation. Based on the transcriptome data, I hypothesize that putative WRI genes (WRI1, 2, 3) of avocado enhance oil content in nonseed tissues. Currently, cloning of Putative PaWRI 1, 2 and 3 genes into a binary vector, followed by agrobacterium-mediated transformation to generate transient and stable transient lines, is underway. Full-length cDNA for PaWRI genes (1 & 2) were amplified and cloned into pK34 entry vector followed by sequence confirmation. PaWRI genes (1 & 2) were subcloned into pB110 destination vector and will be transformed into agrobacterium for their integration into the plants. Cloning of WRI3 is still ongoing. Transient expression of putative PaWRI 1, 2 and 3 genes, will be validated using tobacco leaf assay, are expected to enhance oil accumulation in leaf tissues. Agrobacterium bearing PaWRI genes and a viral silencing protein (p19) will be co-infiltrated on to the underside of Nicotiana benthamiana leaves. Infiltrated plants will be placed in growth room with 16:8 light/dark cycle. Four days post infiltration, infected leaf areas will be harvested and TAG content and composition will be determined by gas chromatography coupled with flame ionization detector. Functional validation of these orthologs is expected to reveal the preferred WRI isoform that likely participates in regulation of oil biosynthesis in avocado mesocarp. Additionally, this work may also elucidate the differences between regulation of TAG accumulation in seed and non-seed tissues and identify new targets to enhance TAG biosynthesis in plants.
26
Bhatia, Shina, e Aruna Kilaru. "Functional Validation of Wrinkled Orthologs in Avocado Oil Biosynthesis". Digital Commons @ East Tennessee State University, 2016. https://dc.etsu.edu/etsu-works/4832.
Testo completoAbstract (sommario):
Triacylglycerol (TAG) is a class of lipid molecules composed of three fatty acyl chains esterified to a glycerol backbone. In plants, TAG is synthesized in various tissues and serves as a carbon and energy source. Oil biosynthesis is well understood in oilseeds however how plants store oil in non-seed tissue is yet to be determined. In Avocado (Persea americana), a basal angiosperm, TAG is exclusively accumulated in mesocarp tissue and therefore is emerging as a model system to uncover underlying mechanisms of TAG biosynthesis in tissues other than seed. The mesocarp of Avocado fruit contains ~60-70% of oil by dry weight. Recent transcriptome studies revealed that the TAG biosynthesis is transcriptionally regulated in non-seed tissues. In seed tissues, TAG biosynthesis is regulated by many seed maturation factors directly or indirectly through downstream transcription factor WRINKLED1 (WRI1). Transcriptome studies revealed that in addition to ortholog of WRI1, orthologs for WRI2 and WRI3 were also highly expressed in avocado mesocarp during the period of oil accumulation. Currently, cloning of Putative PaWRI 1, 2 and 3 genes into a binary vector, followed by agrobacterium-mediated transformation to generate transient and stable transient lines, is underway. Transient expression of putative PaWRI 1, 2 and 3 genes, using tobacco leaf assay, are expected to enhance oil accumulation in leaf tissues. Stable expression of PaWRI 1, 2, and 3 in Atwri-/- is expected to restore oil accumulation in seeds. TAG content and composition will be determined by gas chromatography coupled with flame ionization detector. Functional validation of these orthologs is expected to reveal the preferred WRI isoform that likely participates in regulation of oil biosynthesis in avocado mesocarp. Additionally, this work may also elucidate the differences between regulation of TAG accumulation in seed and non-seed tissues and identify new targets to enhance TAG biosynthesis in plants.
27
Rahman, Md Mahbubar, Ha-Jung Sung, Andrew Campbell, Emily Gall e Aruna Kilaru. "Characterization of Acyltransferases Involved in Tag Biosynthesis in Avocado". Digital Commons @ East Tennessee State University, 2014. https://dc.etsu.edu/etsu-works/4852.
Testo completoAbstract (sommario):
Triacylglycerol (TAG) is a main storage lipid in seeds and is utilized for seed germination. Humans commonly consume TAG in the form of vegetable oil. Currently, TAG contributes to 25% of the total calories consumed in the developed countries and dependency for biofuel production from plants lipid is also increasing day by day. By 2030 the expected consumption level of vegetable oil will be double and to fulfill this demand it is necessary to increase the oil production in plants. To accomplish this goal, it is pertinent to understand the regulation of TAG accumulation in plants. Avocado (Persea americana), a basal angiosperm, stores up to 70% oil in the form of TAG in nonseed tissue (mesocarp). Here, we use it avocado as a model system to understand TAG biosynthesis in tissues other than seed. In plants, TAG biosynthesis may involve acyl-CoA–dependent or –independent pathway catalyzed by diacylglycerol acyltransferases (DGAT) and phospholipid: diacylglycerol acyltransferases (PDAT), respectively. RNA-Seq and Q-PCR analysis of developing mesocarp of avocado revealed higher expression for DGAT1 and PDAT1, coinciding with the period of TAG accumulation. Therefore, we hypothesize that DGAT1 and PDAT1 are responsible for catalyzing the terminal step in TAG biosynthesis in Avocado mesocarp. Using the transcriptome data, we identified full-length coding sequences for DGAT1 and PDAT1. These acyltransferases are being cloned and will be characterized for their enzyme activity and substrate specificity, subsequent to their expression in yeast. Complementation of Arabidopsis dgat1 and pdat1 mutants and phenotypic characterization will also be carried out using Gateway-cloning techniques and transgenic lines will be assayed for TAG content in seeds. This study is expected to provide basic understanding of TAG accumulation in avocado mesocarp tissue.
28
Sung, Ha-Jung. "Identification of Acyltransferases Associated with Triacylglycerol Biosynthesis in Avocado". Digital Commons @ East Tennessee State University, 2013. https://dc.etsu.edu/etd/2311.
Testo completoAbstract (sommario):
A variety of plants synthesize and store oil in the form of triacylglycerols (TAG) in their seed and nonseed tissues that are commonly used as vegetable oils. In seed tissues, an acyl CoA-dependent diacylglycerol (DAG) acyltransferase (DGAT) and/or -independent phospholipid:DGAT (PDAT) catalyze the conversion of DAG to TAG. In avocado fruit, which stores up to 70% oil by dry weight in mesocarp, it is hypothesized that both DGAT and PDAT are likely involved in TAG synthesis. To investigate, TAG content and composition and transcript levels for the acyltransferases in avocado fruit were quantified by gas chromatography and real-time polymerase chain reaction, respectively. Temporal, tissue-specific and phenotypic comparisons revealed that while DGAT1 gene expression was specifically associated with TAG accumulation, PDAT also correlated with higher levels of polyunsaturated fatty acid; DGAT2 was barely detectable. These studies suggest that TAG biosynthesis in nonseed tissues of avocado involves acyl CoA-dependent and -independent reactions.
29
Ramos-Jerz, María del Refugio. "Phytochemical analysis of avocado seeds (Persea americana Mill., c.v. Hass)". Göttingen Cuvillier, 2007. http://d-nb.info/98608638X/04.
Testo completo
30
Mostert, ME, BM Botha, Plessis LM Du e KG Duodu. "Short Communication Effect of fruit ripeness and method of fruit drying on the extractability of avocado oil with hexane and supercritical carbon dioxide". Society of Chemical Industry, 2007. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1000806.
Testo completoAbstract (sommario):
Background: Oil yield from avocado fruit may be influenced by fruit pre-treatment and extraction method.
Unripe and ripe avocado fruit pieces were deep-frozen at −20 ◦C and either freeze-dried or oven-dried (80 ◦C). Oil
yield from these samples was determined after extraction with hexane and supercritical carbon dioxide (SC-CO2).
The fruit samples were examined using scanning electron microscopy before and after oil extraction.
RESULTS: Average oil yield from ripe fruit (freeze-dried and oven-dried combined) was 72 g kg−1 higher than
from unripe fruit for SC-CO2 extracts and 61 g kg−1 higher for hexane extracts. This may be due to enzymatic
degradation of parenchyma cell walls during ripening, thus making the oil more available for extraction. Freezedried
samples had a mean oil yield 55 g kg−1 greater than oven-dried samples for SC-CO2 extracts and 31 g kg−1
higher for hexane extracts. However, oil yields from ripe fruit (freeze-dried and oven-dried) subjected to hexane
extraction were not significantly different. All hexane extracts combined had a mean oil yield 93 g kg−1 higher than
SC-CO2 extracts.
CONCLUSION: SC-CO2 may be more selective and may create paths of least resistance through the plant
material. Hexane, on the other hand, is less selective and permeates the whole plant material, leading to more
complete extraction and higher oil yields under the experimental conditions.
31
Basuki, Eko. "Physiological and biochemical responses of avocado fruit to controlled atmosphere storage /". Richmond, N.S.W. : Faculty of Science and Technology, University of Western Sydney, Hawkesbury, 1998. http://library.uws.edu.au/adt-NUWS/public/adt-NUWS20030523.095552/index.html.
Testo completo
32
behera, Jyoti R., e aruna Ranjan kilaru. "NOVEL STRUCTURAL CHARACTERISTICS OF OIL BIOSYNTHESIS REGULATOR PROTEIN IN AVOCADO". Digital Commons @ East Tennessee State University, 2021. https://dc.etsu.edu/asrf/2021/presentations/21.
Testo completoAbstract (sommario):
Plants synthesize and store oil, mostly triacylglycerol (TAG), in various storage tissues that serves as a source of carbon and energy. The process is transcriptionally controlled by WRINKLED1 (WRI1), a member of the APETALA2 (AP2) class of transcription factors, that regulates most of the fatty acid biosynthesis genes. Among the four Arabidopsis WRI1 paralogs, only WRI2 is nonfunctional and failed to complement wri1-1 mutant seeds. The oleaginous Avocado (Persea americana) fruit mesocarp (60-70% DW oil) showed high expression levels for orthologs of WRI2, along with WRI1 and WRI3. While the role of WRI1 as a master seed oil biosynthesis regulator is well-established, the function of WRI1 paralogs in non-seed tissues is poorly understood. We conducted structural analyses to elucidate distinct features of avocado WRI paralogs compared to their orthologs in seed tissues. Comprehensive comparative in silico analyses of WRI1 paralogs from Arabidopsis (dicot), maize (monocot), and avocado revealed distinct features associated with their function. Our analysis showed the presence of only one AP2 domain in all WRI2 orthologs, compared to two AP2 in others. The highly conserved N-terminal region and the less conserved C-terminal regions make up the primary structure of the proteins, with amino acid composition bias characteristic of intrinsically disordered proteins (IDPs). Additionally, the avocado WRI2 showed a high proportion of random coil secondary structure, although it lacks a C-terminal intrinsically disordered region (IDR). Also, both WRI1 and WRI2 have distinct predicted phosphorylation target sites compared to their orthologs, whereas WRI2 lacks a PEST motif. Finally, through transient expression assays, we demonstrated that both avocado WRI1 and WRI2 are functional and drive TAG accumulation in Nicotiana benthamiana leaves. Our study showed that avocado WRI2 is structurally different and is functional, unlike its ortholog in Arabidopsis. This study provides us with new targets to enhance oil biosynthesis in plants.
33
Rahman, Md Mahbubar, Jay Shockey e Aruna Kilaru. "Identification And Functional Analysis Of Avocado Dgat1 Expressed In Yeast". Digital Commons @ East Tennessee State University, 2017. https://dc.etsu.edu/etsu-works/4787.
Testo completoAbstract (sommario):
The avocado mesocarp contains up to 60-70% oil by dry weight where triacylglycerol (TAG) is the major constituent. There is significant human nutritional demand for vegetable oil, but its use in production of renewable biomaterials and fuels has intensified the need to further increase oil production. In plants, the final and committed step in TAG biosynthesis is catalyzed by diacylglycerol acyltransferases (DGAT) and/or a phospholipid: diacylglycerol acyltransferases (PDAT). Both DGAT and PDAT contribute to TAG biosynthesis in an independent or overlapping manner, depending on the species. However, preferred pathway for TAG biosynthesis is not well studied in nonseed tissues such as mesocarp. Based on the transcriptome data of Persea americana it is hypothesized that both DGAT and PDAT are likely to catalyze the conversion of diacylglycerol to TAG. In this study, putative DGAT1 was identified and comprehensive in silico analyses were conducted to determine the respective start codons, full-length coding sequences, transmembrane domains, predicted protein structures and phylogenetic relationships with other known DGAT1s. These data reveal that the putative DGAT1 of a basal angiosperm species retain features that are conserved not only among angiosperms but also other eukaryotes. For further functional analysis, the avocado DGAT1 was expressed in H1246, a TAG-deficient yeast strain and lipotoxicity rescue assays, TLC analysis, Nile Red staining were conducted. The complementation of this yeast strain confirmed enzyme activity and supported the possible role of avocado DGAT1 in TAG biosynthesis. Finally, substrate specificity of DGAT was determined by incubating microsomes with different radiolabeled substances and found that avocado DGAT1 has a preference toward oleic acid (18:1) compared to palmitic acid (16:0) while it is converting diacylglycerol (DAG) to triacylglycerol. In summary, we characterized functional DGAT1 in a basal angiosperm species, which may be metabolically engineered into crop species to produce TAG enriched in oleic acid.
34
Rahman, Md Mahbubar, Jay Shockey e Aruna Kilaru. "Identification, and Heterologous Expression Analysis of Avocado DGAT1 and DGAT2". Digital Commons @ East Tennessee State University, 2015. https://dc.etsu.edu/etsu-works/4796.
Testo completoAbstract (sommario):
The neutral lipid triacylglycerol (TAG) is the main storage lipid in plants. When stored in seeds, TAG provides the carbon and energy source during germination. There is significant human nutritional demand for vegetable oil, but its use in production of renewable biomaterials and fuels has intensified the need to increase oil production. In plants, the final and committed step in TAG biosynthesis is catalyzed by diacylglycerol acyltransferases (DGAT) and/or a phospholipid: diacylglycerol acyltransferases (PDAT). Both DGAT and PDAT contribute to seed TAG biosynthesis in an independent or overlapping manner, depending on the species. However, in nonseed tissues such as mesocarp of avocado, the regulation of TAG biosynthesis is not well-studied. Based on the transcriptome data of Persea americana it is hypothesized that both DGAT and PDAT are likely to catalyze the conversion of diacylglycerol to TAG. In this study, putative DGAT1 and DGAT2 were identified and comprehensive in silico analyses were conducted to determine the respective start codons, full-length coding sequences, transmembrane domains, predicted protein structures and phylogenetic relationships with other known DGATs. These data reveal that the putative DGATs of a basal angiosperm species retain features that are conserved not only among angiosperms but also other eukaryotes. For further biochemical characterization, the avocado DGATs were expressed in a TAGdeficient yeast strain and lipotoxicity rescue assays were conducted. The complementation of this yeast strain confirmed enzyme activity and supported the possible role of both avocado DGATs in TAG biosynthesis. Future studies will be focused on determining the substrate specificity of DGAT and its role, relative to PDATs in TAG biosynthesis in avocado mesocarp.
35
Kilaru, Aruna, Xia Cao, Ha-Jung Sung, Parker Dabbs, Mahbubur Md Rahman, Keithanne Mockaitis e John B. Ohlrogge. "Developmental Profiles Of The Avocado Fruit Transcriptome During Oil Accumulation". Digital Commons @ East Tennessee State University, 2014. https://dc.etsu.edu/etsu-works/4805.
Testo completoAbstract (sommario):
Unlike most other fruits that accumulate oil in seed tissues, avocado stores large amounts of oil in the form of triacylglycerol (TAG) in its mesocarp tissue. The regulation of TAG biosynthetic pathways in such nonseed tissues is poorly understood. RNA-Seq was used to identify the transcriptional networks underlying TAG biosynthesis in developing mesocarp of avocado. Deep transcriptional profiling studies revealed that several transcripts were differentially represented between the early and late developmental stages of mesocarp. The temporal expression pattern of transcripts associated with fatty acid biosynthesis in plastid coincided with increasing oil content. Furthermore, except for the transcripts that likely encode enzymes involved in the terminal step in TAG synthesis, others involved in TAG assembly in the endoplasmic reticulum were poorly expressed. This pattern of higher expression for genes involved in fatty acid synthesis but not TAG assembly was similar to previously observed pattern in other seed and nonseed tissues. Comparative analysis of transcript levels for about 1500 transcription factors, across different species and oil-storing tissues, also revealed that WRINKLED1 may be highly conserved across species but transcriptional regulation of oil biosynthesis, includes distinct tissue-specific features. In conclusion, while the biochemical pathways for oil biosynthesis in nonseed tissue are highly similar to that of seed tissues, certain distinctive modes of regulation of fatty acid biosynthesis and TAG assembly likely occur in oil-rich nonseed tissues.
36
Sung, Ha-Jung, e Aruna Kilaru. "Identification of Acyltransferases Associated with Oil Accumulation in Avocado Fruit". Digital Commons @ East Tennessee State University, 2013. https://dc.etsu.edu/etsu-works/4806.
Testo completoAbstract (sommario):
In avocado, an economically important crop, fruits can store up to 70 % oil in the form of triacylglycerols (TAGs). While TAG synthesis in seed tissues mostly depends on an acyl CoA-dependent enzyme, diacylglycerol (DAG) acyltransferase (DGAT) to catalyze the conversion of DAG to TAG, the enzymes involved in non-seed tissues remains to be elucidated. Recent studies on oil palm suggested participation of an acyl-CoA-independent enzyme, phospholipid:diacylglycerol acyltransferase (PDAT), in TAG synthesis. Our research focuses on identifying acyltransferases involved in oil accumulation in mesocarp tissues of avocado. Furthermore, in ‘Hass’ avocado, where 20-60 % of the fruit are phenotypically small, even under favorable conditions, we are interested in determining the association between oil accumulation and fruit size. To this extent, we quantified gene expression levels for DGAT 1 and 2 and PDAT and the rate of oil accumulation in developing mesocarp (oilrich) and seed (non-oil rich) tissues of phenotypically 'small' and 'normal' fruits, using real-time PCR and gas chromatography, respectively. Candidate acyltransferase genes, highly expressed in mesocarp but not in seed, will be cloned and characterized. Understanding TAG synthesis in non-seed tissues will allow us to develop genetic tools necessary for generating bioenergy-rich crops.
37
Sung, Ha-Jung, e Aruna Kilaru. "Identification of Acyltransferases Associated with Triacylglycerol Biosynthesis in Avocado Fruit". Digital Commons @ East Tennessee State University, 2012. https://dc.etsu.edu/etsu-works/4865.
Testo completoAbstract (sommario):
Modern society’s demand for oil has resulted in depletion of resources and caused higher oil prices. Therefore, natural oil resources of plants are gaining the spotlight and are expected to increase twice that of current use by 2030. Plants are able to accumulate up to 90% oil by dry weight in the form of triacylglycerol (TAG) and it is derived from fleshy part of the fruits, such as mesocarp of oil palm, avocado, and olive. In seed tissues, an acyl CoA-dependent enzyme, diacylglycerol acyltransferase (DGAT) participates in conversion of diacylglycerol (DAG) to TAG. However, TAG can also be formed by an acyl CoA- independent enzyme, phospholipid:diacylglycerol acyltransferase (PDAT). Avocados (Persea americana) store up to ~70% oil in mesocarp and I am interested in identifying the acyltransferase involved in oil biosynthesis in mesocarp tissues. Based on the transcriptome data available, I hypothesize that unlike in seeds, both DGAT and PDAT are associated with TAG biosynthesis in developing mesocarp of avocado. To test this hypothesis, I will determine 1) TAG content and composition and 2) expression levels for DGAT and PDAT genes in mesocarp and seed tissues of five stages of developing fruits of avocado (n=5). Total lipids will be extracted by isopropanol-chloroform method and analyzed for composition as methyl esters on GC-FID. Total RNA, for expression analysis, will be extracted by Trizol method and analyzed with gene-specific primers by real-time PCR. Statistical significance in change in oil content in association with gene expression during fruit development between mesocarp and seed tissues will be analyzed by ANOVA repeated measures. Comparison of temporal gene expression pattern of oil accumulation mesocarp, to that of seed, will allow us to differentiate the acyltransferase(s) specifically associated with TAG biosynthesis. The proposed research work will take the field of plant lipid biochemistry a step forward in understanding TAG synthesis in fruit tissue. Specifically, I will be able to clearly demonstrate the association of a particular acyltransferase to increasing lipid content in a non-seed (mesocarp) tissue. Understanding differences in oil regulation of a basal angiosperm (avocado) in relation to a monocot (oil palm) and a dicot (olive) also will provide additional insights into fundamental changes in TAG biosynthesis during the evolution of flowering plants. My research is part of a global project that includes a group in California, Florida and Israel. Data generated from my proposed work will be used to develop a joint Binational Agricultural and Research proposal. Therefore, my research work will subsequently contribute to development of ways to manipulation of extent and timing of oil accumulationa direct benefit to avocado growers. Furthermore, this study will be a pivotal step to understanding TAG synthesis that will lead to bioenergy crop.
38
Kiunga, Josphat K., e Aruna Kilaru. "Functional Complementation of Arabidopsis Mutants by Avocado PDAT1 and DGAT1". Digital Commons @ East Tennessee State University, 2020. https://dc.etsu.edu/etsu-works/7729.
Testo completo
39
Efendi, Darda. "Transformation and cryopreservation of embryogenic avocado (Persea americana Mill.) cultures". [Gainesville, Fla.] : University of Florida, 2003. http://purl.fcla.edu/fcla/etd/UFE0001339.
Testo completo
40
Siddique, Shaikh. "Cold plasma inhibits growth and germination of avocado postharvest pathogens". Thesis, Siddique, Shaikh (2018) Cold plasma inhibits growth and germination of avocado postharvest pathogens. PhD thesis, Murdoch University, 2018. https://researchrepository.murdoch.edu.au/id/eprint/50154/.
Testo completoAbstract (sommario):
Cold plasma (CP) is composed of highly reactive species including gas molecules, charged particles in the form of positive ions, negative ions, free radicals and electrons at near-room temperature. CP has been demonstrated to successfully decontaminate food materials from food-borne pathogens at atmospheric pressure and offers new chemical-free sterilisation opportunities for the food sector. The efficacy of CP to control postharvest fungal pathogens is poorly studied. This study investigated the effects of CP generated in both open and sealed conditions, on the growth of Colletotrichum alienum and C. fioriniae, two important postharvest fungal pathogens of avocado (Persea americana cv. ‗Hass‘). In addition, plasma activated water (PAW) was tested on C. alienum. In vitro, mycelial growth and conidia germination decreased as the duration of CP treatment increased, with no mycelial growth or germination of conidia occurring after 6 min of treatment. PAW also decreased conidial germination, even when the PAW had been stored for 15 days prior to use. Optical emission spectroscopy identified production of active oxygen and nitrogen species during CP treatment. These were assumed to be responsible for the observed reduction in conidial germination. Transmission electron microscopy showed the majority of conidia treated with CP and PAW were deformed, with changes to the cell wall, and disorganised vacuoles and cytoplasm. In addition, some conidia also had disrupted nuclei and mitochondria after both treatments. In planta, CP treatment for up to 5 min was not phytotoxic to avocado fruit, and fruit were firmer compared to untreated and fungicide treated controls. However, significant variability was observed in individual fruit response to CP. CP treatment appeared to reduce postharvest body rot and stem end rot symptoms but this was not significantly different to the untreated control. It was assumed that CP either slowed the growth of the pathogens in the treated fruit or delayed the ripening of the fruit. These data suggest that cold plasma has the potential to be applied as a postharvest treatment for C. alienum and C. fioriniae on avocado fruit, and may contribute to reducing food wastage caused by these pathogens.
41
Christie, John Barry. "Determining the phenotypic resistance mechanisms in avocado against Phytophthora cinnamomi". Diss., University of Pretoria, 2012. http://hdl.handle.net/2263/31497.
Testo completoAbstract (sommario):
The avocado (Persea americana Mill.) is an economically important crop worldwide. The most important disease of avocado is Phytophthora root rot, which is caused by Phytophthora cinnamomi Rands. Currently, phosphonate trunk injections provide satisfactory disease control; however, the possibility of reduced sensitivity and eventually resistance to this fungicide is lurking on the horizon. Furthermore, consumer demands for “organic” fruit has been increasing over the past decade, emphasising the need to use root rot-resistant rootstocks. Due to a lack of understanding of the interaction between these two organisms, screening for specific resistant mechanisms is not possible and consequently only partially resistant rootstocks are currently commercially available. The aim of this thesis was therefore to address this need by investigating phenotypic traits in avocado rootstocks that could play a role in resistance against P. cinnamomi.Dissertation (MSc)--University of Pretoria, 2012.
Microbiology and Plant Pathology
MSc
Unrestricted
42
MacDonald, Brendan. "Is Avocado Toast the Reason I'm Still Living with My Parents?" Scholarship @ Claremont, 2018. http://scholarship.claremont.edu/cmc_theses/1762.
Testo completoAbstract (sommario):
Is avocado toast the reason that I am still living with my parents? In other words, does the consumption of avocado toast, or more specifically eating out in general, have any impact on one’s ability to be a homeowner. In May of 2017, an Australian real estate developer by the name of Tim Gurner was asked to provide advice to young people who could not afford to purchase a home. He responded by saying, “when I was trying to buy my first home, I wasn’t buying smashed avocado for $19 and four coffees at $4 each,” (Victor, 2017). While the claim may appear to be laughable at first glance, this is not the first time that statements such as this have been made.
The United States Census Bureau tells us that annual homeownership rates for individuals under the age of 35 has been on the steady decline. Additionally, per Goldman Sachs, it is known that the percentage of adults age 18-31 that were married and living in their own homes has decreased from 56% in 1968 to 23% in 2012. This paper assesses and compares the spending habits of different generations, working to discern if there are notable differences particularly between Millennials and other generations. Data sets from the Consumer Expenditure Survey (CEX) and Zillow between the years 2000-2013 were examined. Although there is not data on avocado toast specifically, it is possible to broaden the hypothesis to examine the expenditures on the consumption of meals prepared away from home. For the purpose of this study, I take Tim Gurner’s statement and apply it more broadly to the idea of spending money on the experience of eating out. The results show that the consumption of avocado toast, defined as money spent on meals prepared away from home, does not have an impact on whether an individual owns a home, nor is it an indicator as to whether they will be renters or living with their parents. Rather, the results indicate that owning a home leads to consuming more avocado toast. This means that although it is commonly perceived that Millennials are consumers as opposed to savers, their inability to afford home ownership does not have any direct connection to their spending habits on avocado toast, and more broadly, eating out in general.
43
Meyer, Marjolaine Dorothee. "Effect of controlling ethylene on ripening of avocado cv. Hass fruit". Thesis, Cranfield University, 2010. http://dspace.lib.cranfield.ac.uk/handle/1826/10459.
Testo completoAbstract (sommario):
Rigorous control of ethylene inside storage atmosphere is cardinal to maintain quality of climacteric fruit, including avocado cv. Hass. This can be achieved using the ethylene action inhibitor, 1-methylcyclopropene (1-MCP). The recent development of a novel palladium (Pd)-based ethylene scavenger, e+® Ethylene Remover, provides a new opportunity to delay avocado fruit ripening. A new method was developed to sequentially extract and quantify both lipids and sugars from the same avocado mesocarp tissue sample. Extraction by homogenization with hexane yielded slightly less oil than the standard Soxhlet technique whilst the fatty acid profiles of the oil extracts were similar. Extraction of the resulting filter residue with methanol (62.5%, v/v) better recovered sucrose, perseitol and mannoheptulose as compared to ethanol (80%, v/v). The new method has a shorter extraction time, lower extraction temperature and requires less solvent. Presence of e+® Ethylene Remover in storage atmosphere removed all ethylene and accordingly delayed the ripening of avocado cv. Hass stored at low temperature. 1-MCP also inhibited ripening, yet, unlike e+® Ethylene Remover it impaired subsequent ripening. It was possible to slow down the ripening rate after the climacteric has been induced by removing ethylene below 1 μL L-1 in presence of e+® Ethylene Remover, and the scavenger was effective in combination with modified atmosphere packaging (MAP). Blocking ethylene action or removing ethylene did very slightly affect the fatty acid composition of the mesocarp oil. Depending on the origin and maturity of the fruit, 1-MCP and e+® Ethylene Remover better maintained seven-carbon sugars concentrations in mesocarp. Results support the view that mannoheptulose and perseitol could be important features of the avocado ripening process but more research is necessary to elucidate their exact function. Mesocarp abscisic acid (ABA) was quantified using a newly developed LC-ESIMS/ MS method. ABA increased as fruit ripened but appeared to be at least partly regulated by ethylene. Whether ABA influences the ethylene-associated ripening in avocado cv. Hass remains to be determined in future.
44
Basuki, Eko, of Western Sydney Hawkesbury University e Faculty of Science and Technology. "Physiological and biochemical responses of avocado fruit to controlled atmosphere storage". THESIS_FST_XXX_Basuki_E.xml, 1998. http://handle.uws.edu.au:8081/1959.7/335.
Testo completoAbstract (sommario):
The primary objective of the research was to study the physiological and biochemical changes in Hass avocado fruit stored in different combination of oxygen and carbon dioxide concentrations at both 0 degrees and 5 degrees Centigrade (C), and to determine whether storage in controlled atmosphere (CA) can decrease the incidence of chilling injury (CI). A secondary objective was to identify possible correlations between CA, the incidence of CI, the activity of some ripening related enzymes and changes in proteins during ripening at 20 degrees C following storage at low temperatures. Fruit suffered no CI and ripened normally following CA storage for 3 weeks at both 0 degrees and 5 degrees C, then transferred to air for 6 days at 20 degrees C. CI symptoms did develop after CA storage for 6 and 9 weeks at 0 degrees C. Changes in proteins during ripening were analysed by 2D-PAGE. Some polypeptides were detected in unripe fruit but decreased with ripening. Polypeptides of 16.5, 25, 36 and 56 kD (kilo Dalton) were present early in ripening and their levels further increased during ripening. The appearance of three ripening related polypeptides with estimated molecular weights 80 kD (pI 3.6), 36 kD (pI 5.8) and 16.5 kD (pI 5.7) was observed in fruit at the climacteric stage. Three polypeptides with estimated molecular weights of 41 kD (pI7.8), 36 kD (pI 5.8) and 33 kD (pI 5.1) were found in air stored fruit but were not detected in fruit stored in CA. This research showed that CA did not ameliorate CI at 0 degrees C, instead storage at 0 degrees C caused a premature increase in ethylene production when the fruit were returned to air at 20 degrees C. In contrast, CA storage at 5 degrees C retarded ethylene production and ripening in fruit after it was returned to air at 20 degrees C.Doctor of Philosophy (PhD)
45
Tungtirmthong, Juejun. "Biological and physiological changes in relation to avocado and papaya ripening". Thesis, University of Lincoln, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.442497.
Testo completo
46
Wang, Lesley. "Documentation and analysis of avocado oil extraction technologies in Leguruki, Tanzania". Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/105662.
Testo completoAbstract (sommario):
Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 56-57).
A team of MIT students and researchers as well as a local team in Leguruki, Tanzania has been working on extracting oil from excess supplies of avocados since 2014 with the goal of adapting oil extraction methods to small-scale farmers. Through this process of extracting oil, the team has explored several iterations of avocado dryers, presses, and centrifuges. Analyzing this machinery has given a broader picture of the commonalities and requirements of the designs. A set of evaluation criteria can be extracted from this analysis. Having these guidelines in place for future designs for oil extraction will streamline and aid the process, facilitating the small-scale production of avocado oil, and eventually augmenting the incomes of small-scale farmers.
by Lesley Wang.
S.B.
47
Kilaru, Aruna, Xia Cao, Ha-Jung Sung, Keithanne Mockaitis e John B. Ohlrogge. "A Conserved Regulation of Oil Biosynthesis in Avocado, a Basal Angiosperm". Digital Commons @ East Tennessee State University, 2013. https://dc.etsu.edu/etsu-works/4807.
Testo completoAbstract (sommario):
Avocado is an economically important crop with ~ 60-70 % oil, by dry weight, in its fruit mesocarp tissue. The steady increase in global demand for avocado (9% per year) has driven interest to identify the biochemical and molecular factors that regulate its triacylglycerol (TAG, oil) biosynthesis. Using 454- and Illumina-based RNA-Seq approaches, we examined the transcriptional basis for TAG biosynthesis in developing mesocarp of avocado, in relation to other seed and non-seed tissues. Deep transcriptional profiling data allowed us to identify several transcripts that were differentially represented between the early and late developmental stages of mesocarp. Additionally, in all oil-rich tissues analyzed, irrespective of the species, an increased expression was noted for genes mostly associated with fatty acid biosynthesis in plastid, but much less increase in those for TAG assembly in the endoplasmic reticulum. Transcripts associated with hexose metabolism in plastid also showed higher expression, relative to cytosol; this is likely associated with the need for high pyruvate flux directed toward plastid fatty acid synthesis. Moreover, WRINKLED1 transcription factor, a regulatory element associated with oil biosynthesis in seed and non-seed tissues of monocot and dicot plants, was identified in avocado as well. Our studies point to distinctive modes of regulation of fatty acid biosynthesis and TAG assembly that are conserved in both seed and non-seed oil-rich plants. In addition to improving avocado oil production, our study will lead to understanding regulation of oil biosynthesis in coordination with fruit development and identification of ways to generate oil-rich bioenergy crops; a direct implication for the science & society. This study provides an evolutionary insight into conserved nature of oil biosynthesis in a basal angiosperm (avocado) in relation to a monocot (oil palm) and a dicot (brassica). This research will lead to publications for students, sustain existing collaborations (Israel, CA, FL avocado researchers) and generate external funds.
48
Sung, Ha-Jung, e Aruna Kilaru. "Identification of Key Genes Associated with Triacylglycerol Biosynthesis in Avocado Fruit". Digital Commons @ East Tennessee State University, 2013. https://dc.etsu.edu/etsu-works/4861.
Testo completoAbstract (sommario):
A variety of plants are natural resources for oil and are capable of synthesizing and storing up to 90% oil (dry weight) in the form of triacylglycerols (TAGs). TAGs are commonly used as vegetable oils of which, >35% is derived from fleshy part of the fruits, such as mesocarp of oil palm, avocado, and olive. Studies on TAG synthesis in seed tissues mostly implicated an acyl CoA-dependent enzyme, diacylglycerol (DAG) acyltransferase (DGAT) to catalyze the conversion of DAG to TAG. However, recent studies on Arabidopsis and oil palm suggested participation of a phospholipid:diacylglycerol acyltransferase (PDAT), which is an acyl-CoA-independent enzyme. In avocados, which store up to 70% oil in mesocarp, I hypothesize that both DGAT and PDAT are likely involved in TAG synthesis. To test the hypothesis, I determined TAG content and composition by gas chromatography (GC) and expression levels of DGAT and PDAT genes by real-time PCR, in developing mesocarp. These data will be compared to that of seed tissues of avocado to associate gene expression levels with changes in oil accumulation. Future studies on cloning and characterization of these potential acyltransferase genes involved in TAG synthesis will allow us to develop genetic tools that may increase oil yield; a step towards meeting the consumption demand for oil that is expected to almost double by 2030.
49
Behera, Jyoti, e Aruna Kilaru. "Structural and Functional Characterization of Avocado Transcriptional Factor in Oil Biosynthesis". Digital Commons @ East Tennessee State University, 2020. https://dc.etsu.edu/etsu-works/7736.
Testo completo
50
Basuki, Eko. "Physiological and biochemical responses of avocado fruit to controlled atmosphere storage". Thesis, Richmond, N.S.W. : Faculty of Science and Technology, University of Western Sydney, Hawkesbury, 1998. http://handle.uws.edu.au:8081/1959.7/335.
Testo completoAbstract (sommario):
The primary objective of the research was to study the physiological and biochemical changes in Hass avocado fruit stored in different combination of oxygen and carbon dioxide concentrations at both 0 degrees and 5 degrees Centigrade (C), and to determine whether storage in controlled atmosphere (CA) can decrease the incidence of chilling injury (CI). A secondary objective was to identify possible correlations between CA, the incidence of CI, the activity of some ripening related enzymes and changes in proteins during ripening at 20 degrees C following storage at low temperatures. Fruit suffered no CI and ripened normally following CA storage for 3 weeks at both 0 degrees and 5 degrees C, then transferred to air for 6 days at 20 degrees C. CI symptoms did develop after CA storage for 6 and 9 weeks at 0 degrees C. Changes in proteins during ripening were analysed by 2D-PAGE. Some polypeptides were detected in unripe fruit but decreased with ripening. Polypeptides of 16.5, 25, 36 and 56 kD (kilo Dalton) were present early in ripening and their levels further increased during ripening. The appearance of three ripening related polypeptides with estimated molecular weights 80 kD (pI 3.6), 36 kD (pI 5.8) and 16.5 kD (pI 5.7) was observed in fruit at the climacteric stage. Three polypeptides with estimated molecular weights of 41 kD (pI7.8), 36 kD (pI 5.8) and 33 kD (pI 5.1) were found in air stored fruit but were not detected in fruit stored in CA. This research showed that CA did not ameliorate CI at 0 degrees C, instead storage at 0 degrees C caused a premature increase in ethylene production when the fruit were returned to air at 20 degrees C. In contrast, CA storage at 5 degrees C retarded ethylene production and ripening in fruit after it was returned to air at 20 degrees C.