oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Regulatory Specialization of Xyloglucan (XG) and Glucuronoarabinoxylan (GAX) in Pericarp Cell Walls during Fruit Ripening in Tomato (Solanum lycopersicum)  [PDF]
Ayami Takizawa, Hiromi Hyodo, Kanako Wada, Tadashi Ishii, Shinobu Satoh, Hiroaki Iwai
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0089871
Abstract: Disassembly of cell wall polysaccharides by various cell wall hydrolases during fruit softening causes structural changes in hemicellulose and pectin that affect the physical properties and softening of tomato fruit. In a previous study, we showed that the changes in pectin during tomato fruit ripening were unique in each fruit tissue. In this study, to clarify the changes in hemicellulose in tissues during tomato fruit ripening, we focused on glucuronoarabinoxylan (GAX) and xyloglucan (XG). GAX was detected only in the skin and inner epidermis of the pericarp using LM11 antibodies, whereas a large increase in XG was detected in all fruit tissues using LM15 antibodies. The activity of hemicellulose degradation enzymes, such as β-xylosidase and α-arabinofuranosidase, decreased gradually during fruit ripening, although the tomato fruits continued to soften. In contrast, GAX and XG biosynthesis-related genes were expressed in all tomato fruit tissues even during ripening, indicating that XG was synthesized throughout the fruit and that GAX may be synthesized only in the vascular bundles and the inner epidermis. Our results suggest that changes in the cell wall architecture and tissue-specific distribution of XG and GAX might be required for the regulation of fruit softening and the maintenance of fruit shape.
1-Methylcyclopropene delays tomato fruit ripening
Moretti, Celso Luiz;Araújo, Alessandra L.;Marouelli, Waldir Aparecido;Silva, Washington Luiz C.;
Horticultura Brasileira , 2002, DOI: 10.1590/S0102-05362002000400030
Abstract: tomato (lycopersicon esculentum mill.) fruits, cv. santa clara, were harvested at the breaker stage from commercial fields in brazlandia, brazil, to investigate the ability of 1-methylcyclopropene (1-mcp) to retard tomato fruit ripening. fruit without external blemishes were graded for size (diameter = 80±5 mm) and mass (m = 130±10 g), placed inside hermetically sealed boxes, and 1-mcp was applied for 12 hours (t = 22±1°c; rh = 80-85%) at four different concentrations: 0 (control), 250, 500 and 1000 ml.l-1. fruits were held at ambient conditions (t = 23±2°c; rh 80-85%) for 2 days and then stored inside a cold room (t = 20±1°c; rh = 85-95%). every 3 days, during a 15-day period, fruits were analyzed for firmness, total soluble solids, titratable acidity, external color, and total carotenoids. firmness of fruit treated with 1000 ml.l-1 was about 88% higher than control fruits after 17 days. the a*/b* ratio, an indicator of skin color, for fruit treated with 1000 ml.l-1 of 1-mcp was 38% lower than control fruits at the end of the storage period. treatments with higher concentrations of 1-mcp delayed total carotenoids synthesis and color development. control fruits stored for 17 days had about 190% more total carotenoids than fruits treated with 1000 ml.l-1 of 1-mcp. postharvest application of 1-mcp was an efficient method to delay tomato fruit ripening. as 1-mcp concentration increased, ripening was further delayed. tomatoes treated with 250, 500, and 1000 ml.l-1 of 1-mcp were delayed by 8 to 11, 11 to 13 and 15 to 17 days, respectively.
The expression of tin gene in prolongated tomato fruit ripening - Lycopersicom esculentum Mill.  [PDF]
Zdravkovi? Jasmina,Markovi? ?ivoslav,Damjanovi? Milan,Zdravkovi? Milan
Genetika , 2003, DOI: 10.2298/gensr0302077z
Abstract: Tomato selection programme, aiming to create a tomato hybrid with better fruit firmness, has been based on adding rin gene in perspective selection material. The fruit firmness has been based on decelerated ripening which prolongs the shelf life. Heterozygote genotypes (rin/+) have considerably longer shelf life that genotypes with uniform ripening (+/+). The effects of rin gene on shelf life have been examined on four experimental hybrids (K 56S K - 18, K - 64 and K -15 - rin/+ genetic configuration) compared with Atina Fl genotype (uniform ripening +/+) K - 91 selected, line (rin/rin) and Fino F1 (DRS) unknown genetic construction and very good fruit firmness. The parameter for shelf life has been the fruit weight loss during the preservation - from harvest till the fading. The weight loss has been recorded every 7th day during two months. The experimental hybrids showed good agro technical characteristics of mid early tomato intended for production in the open field. During the shelf life, the genotype K - 15 faded the most slowly, both in the group of green and mature fruits.
Auxin Response Factor SlARF2 Is an Essential Component of the Regulatory Mechanism Controlling Fruit Ripening in Tomato  [PDF]
Yanwei Hao?,Guojian Hu?,Dario Breitel?,Mingchun Liu?,Isabelle Mila?,Pierre Frasse?,Yongyao Fu?,Asaph Aharoni?,Mondher Bouzayen?,Mohamed Zouine
PLOS Genetics , 2015, DOI: 10.1371/journal.pgen.1005649
Abstract: Ethylene is the main regulator of climacteric fruit ripening, by contrast the putative role of other phytohormones in this process remains poorly understood. The present study brings auxin signaling components into the mechanism regulating tomato fruit ripening through the functional characterization of Auxin Response Factor2 (SlARF2) which encodes a downstream component of auxin signaling. Two paralogs, SlARF2A and SlARF2B, are found in the tomato genome, both displaying a marked ripening-associated expression but distinct responsiveness to ethylene and auxin. Down-regulation of either SlARF2A or SlARF2B resulted in ripening defects while simultaneous silencing of both genes led to severe ripening inhibition suggesting a functional redundancy among the two ARFs. Tomato fruits under-expressing SlARF2 produced less climacteric ethylene and exhibited a dramatic down-regulation of the key ripening regulators RIN, CNR, NOR and TAGL1. Ethylene treatment failed to reverse the non-ripening phenotype and the expression of ethylene signaling and biosynthesis genes was strongly altered in SlARF2 down-regulated fruits. Although both SlARF proteins are transcriptional repressors the data indicate they work as positive regulators of tomato fruit ripening. Altogether, the study defines SlARF2 as a new component of the regulatory network controlling the ripening process in tomato.
Developmental gene regulation during tomato fruit ripening and in-vitro sepal morphogenesis
Glenn E Bartley, Betty K Ishida
BMC Plant Biology , 2003, DOI: 10.1186/1471-2229-3-4
Abstract: Here, we have further examined regulation of putative developmental genes possibly involved in tomato fruit ripening and development. Using molecular biological methods, we have determined the relative abundance of various transcripts of genes during in vitro sepal ripening and in tomato fruit pericarp at three stages of development. A number of transcripts show similar expression in fruits to RIN and PSY1, ripening-associated genes, and others show quite different expression.Our investigation has resulted in confirmation of some of our previous database mining results and has revealed differences in gene expression that may be important for tomato cultivar variation. We present new and intriguing information on genes that should now be studied in a more focused fashion.Red ripe (RR) tomatoes, appealing to the eye as well as the palate, are the result of numerous physiological changes controlled by hormonal, environmental, and developmental signals, causing maturation or differentiation of various fruit tissues simultaneously. These physiological changes affect the visual, textural, flavor, and aroma characteristics to make fruit more appealing to potential consumers for dispersal of seed. One hormonal cue, ethylene evolution, active at the onset of the respiratory burst during ripening in this climacteric fruit, has been scrutinized in detail over the years [1,2]. Transgenic tomato plants, expressing antisense genes for ethylene biosynthesis enzymes, show that ethylene is necessary for tomato fruit ripening [3]. However, something must signal ethylene induction before the climacteric ethylene burst. Because 1-aminocyclopropane-1-carboxylic acid synthase (ACCS), an enzyme involved in ethylene biosynthesis, is induced before the onset of ethylene evolution, it seems reasonable to assume that other factors control early developmental stages of ripening fruit [4,5]. E8, a gene of unknown function, is expressed in the rin mutant, which does not exhibit the climacteric b
Comparison of color indexes for tomato ripening
López Camelo, Andrés F.;Gómez, Perla A.;
Horticultura Brasileira , 2004, DOI: 10.1590/S0102-05362004000300006
Abstract: color in tomato is the most important external characteristic to assess ripeness and postharvest life, and is a major factor in the consumer's purchase decision. degree of ripening is usually estimated by color charts. colorimeters, on the other hand, express colors in numerical terms along the l*, a* and b* axes (from white to black, green to red and blue to yellow, respectively) within the cielab color sphere which are usually mathematically combined to calculate the color indexes. color indexes and their relationship to the visual color classification of tomato fruits vine ripened were compared. l*, a* and b* data (175 observations from eleven cultivars) from visually classified fruits at harvest in six ripening stages according to the usda were used to calculate hue, chroma, color index, color difference with pure red, a*/b* and (a*/b*)2. anova analysis were performed and means compared by duncan's mrt. color changes throughout tomato ripening were the result of significant changes in the values of l*, a* and b*. under the conditions of this study, hue, color index, color difference and a*/b* expressed essentially the same, and the color categories were significantly different in terms of human perception, with hue showing higher range of values. chroma was not a good parameter to express tomato ripeness, but could be used as a good indicator of consumer acceptance when tomatoes are fully ripened. the (a*/b*)2 relationship had the same limitations as chroma. for vine ripened fruits, hue, color index, color difference and a*/b* could be used as objective ripening indexes. it would be interesting to find out what the best index would be if ripening took place under inadequate conditions of temperature and ilumination.
Off-the-Vine Ripening of Tomato Fruit Causes Alteration in the Primary Metabolite Composition  [PDF]
Augusto Sorrequieta,Luciano A. Abriata,Silvana B. Boggio,Estela M. Valle
Metabolites , 2013, DOI: 10.3390/metabo3040967
Abstract: The influence of postharvest fruit ripening in the composition of metabolites, transcripts and enzymes in tomato ( Solanum lycopersicum L.) is poorly understood. The goal of this work was to study the changes in the metabolite composition of the tomato fruit ripened off-the-vine using the cultivar Micro-Tom as model system. Proton nuclear magnetic resonance ( 1H NMR) was used for analysis of the metabolic profile of tomato fruits ripened on- and off-the-vine. Significant differences under both ripening conditions were observed principally in the contents of fructose, glucose, aspartate and glutamate. Transcript levels and enzyme activities of ?-amino butyrate transaminase (EC 2.6.1.19) and glutamate decarboxylase (EC 4.1.1.15) showed differences in fruits ripened under these two conditions. These data indicate that the contents of metabolites involved in primary metabolism, and conferring the palatable properties of fruits, are altered when fruits are ripened off-the-vine.
Tissue Specific Localization of Pectin–Ca2+ Cross-Linkages and Pectin Methyl-Esterification during Fruit Ripening in Tomato (Solanum lycopersicum)  [PDF]
Hiromi Hyodo, Azusa Terao, Jun Furukawa, Naoya Sakamoto, Hisayoshi Yurimoto, Shinobu Satoh, Hiroaki Iwai
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0078949
Abstract: Fruit ripening is one of the developmental processes accompanying seed development. The tomato is a well-known model for studying fruit ripening and development, and the disassembly of primary cell walls and the middle lamella, such as through pectin de-methylesterified by pectin methylesterase (PE) and depolymerization by polygalacturonase (PG), is generally accepted to be one of the major changes that occur during ripening. Although many reports of the changes in pectin during tomato fruit ripening are focused on the relation to softening of the pericarp or the Blossom-end rot by calcium (Ca2+) deficiency disorder, the changes in pectin structure and localization in each tissues during tomato fruit ripening is not well known. In this study, to elucidate the tissue-specific role of pectin during fruit development and ripening, we examined gene expression, the enzymatic activities involved in pectin synthesis and depolymerisation in fruit using biochemical and immunohistochemical analyses, and uronic acids and calcium (Ca)-bound pectin were determined by secondary ion-microprobe mass spectrometry. These results show that changes in pectin properties during fruit development and ripening have tissue-specific patterns. In particular, differential control of pectin methyl-esterification occurs in each tissue. Variations in the cell walls of the pericarp are quite different from that of locular tissues. The Ca-binding pectin and hairy pectin in skin cell layers are important for intercellular and tissue–tissue adhesion. Maintenance of the globular form and softening of tomato fruit may be regulated by the arrangement of pectin structures in each tissue.
Functional characterization of a tomato COBRA-like gene functioning in fruit development and ripening
Ying Cao, Xiaofeng Tang, Jim Giovannoni, Fangming Xiao, Yongsheng Liu
BMC Plant Biology , 2012, DOI: 10.1186/1471-2229-12-211
Abstract: We identified a tomato gene (SlCOBRA-like) homologous to Arabidopsis COBRA, and determined its role in fleshy fruit biology. The SlCOBRA-like gene is highly expressed in vegetative organs and in early fruit development, but its expression in fruit declines dramatically during ripening stages, implying a primary role in early fruit development. Fruit-specific suppression of SlCOBRA-like resulted in impaired cell wall integrity and up-regulation of genes encoding proteins involved in cell wall degradation during early fruit development. In contrast, fruit-specific overexpression of SlCOBRA-like resulted in increased wall thickness of fruit epidermal cells, more collenchymatous cells beneath the epidermis, elevated levels of cellulose and reduced pectin solubilization in the pericarp cells of red ripe fruits. Moreover, transgenic tomato fruits overexpressing SlCOBRA-like exhibited desirable early development phenotypes including enhanced firmness and a prolonged shelf life.Our results suggest that SlCOBRA-like plays an important role in fruit cell wall architecture and provides a potential genetic tool for extending the shelf life of tomato and potentially additional fruits.The ripening of fleshy fruits involves a number of physiological processes including the production of aromatic compounds, nutrients, pigmentation, and softening of flesh to an edible texture [1,2]. These processes have direct impacts not only on fruit firmness, color, flavor and nutritional content, but also on shelf life, consumer acceptability, processing qualities, in addition to pre- and postharvest disease resistance [1,2]. Excessive fruit softening is the main factor contributing to damage during shipping, storage and post-harvest handling [3]. Fruit firmness and texture also affect the integrity of chopped and diced fruit used for canning and fruit products [4]. Because postharvest losses of fresh fruits due to excessive softening can account for as much as 30~40% of total production, consid
Biodiversity in a Tomato Germplasm for Free Amino Acid and Pigment Content of Ripening Fruits  [PDF]
Guillermo Raúl Pratta, Gustavo Rubén Rodríguez, Roxana Zorzoli, Liliana Amelia Picardi, Estela Marta Valle
American Journal of Plant Sciences (AJPS) , 2011, DOI: 10.4236/ajps.2011.22027
Abstract: Free amino acid and pigment composition in fruits at two ripening stages from a selected tomato germplasm was stu-died. The aims were contributing to knowledge on variability of ripening metabolism and identifying more consis-tently the genetic background of the plant material under analysis. Significant differences (p < 0.05) were found among ripening stages and among genotypes within ripening stage for all amino acids and pigments except by asparagine, alanine and chlorophyll b contents. The highest relative amino acid content corresponded to glutamate, glutamine, and GABA though some genotypes had relatively high asparagine content. Glutamate, glutamine and GABA performed oppositely: the former increased along ripening while the latter two decreased in their relative content. A Principal Components (PC) analysis was applied, determining that metabolites having the greatest contribution to general variability were threonine, serine, glutamate, glutamine, glycine, isoleucine, leucine, tyrosine, phenylalanine, lycopene and beta- carotene, which showed the highest association with PC1. Alanine and chlorophylls a and b were highly associated to PC2. These two first PC explained the 62% of the total variation, and genotypes were distributed according to the ripening stage in their coordinates. Accordingly, a Hierarchical Clustering resulted in a dendrogram having a relatively high cophenetic correlation (0.70), in which two well defined groups were obtained according to ripening stage. These results verified the existence of variability in the metabolism of ripening fruit for amino acids and pigments, and allowed to identify unequivocally a set of selected tomato germplasm according to the fruit metabolic profiles in these two ripening stages.
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.