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At least 271 records · Page 15Linked to original sources

PubMed1994

Apple beta-galactosidase. Activity against cell wall polysaccharides and characterization of a related cDNA clone.

A beta-galactosidase was purified from cortical tissue of ripe apples (Malus domestica Borkh. cv Granny Smith) using a procedure involving affinity chromatography on lactosyl-Sepharose. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that two polypeptides of 44 and 32 kD were present in the fraction that showed activity against the synthetic substrate p-nitrophenol-beta-D-galactopyranoside. The enzyme preparation was incubated with polysaccharide extracts from apple cell walls containing beta-(1-->4)-linked galactans, and products of digestion were analyzed by gas chromatography. Small amounts of monomeric galactose were released during incubation, showing that the enzyme was active against native substrates. Amino acid sequence information was obtained from the purified protein, and this showed high homology with the anticipated polypeptide coded by the ethylene-regulated SR12 gene in carnation (K.G. Raghothama, K.A. Lawton, P.B. Goldborough, W.R. Woodson [1991] Plant Mol Biol 17: 61-71) and a harvest-related pTIP31 cDNA from asparagus (G. King, personal communication). Using the asparagus cDNA clone as a probe, an apple homolog (pABG1) was isolated. This clone contains a 2637-bp insert, including an open reading frame that codes for a polypeptide of 731 amino acids. Cleavage of an N-terminal signal sequence would leave a predicted polypeptide of 78.5 kD. Genomic DNA analysis and the isolation of other homologous apple clones suggest that pABG1 represents one member of an apple beta-galactosidase gene family. Northern analysis during fruit development and ripening showed accumulation of pABG1-homologous RNA during fruit ripening. Enzyme activity as measured in crude extracts increased during fruit development to a level that was maintained during ripening.

Amino Acid Sequence↗

PubMed2025

CRISPR/Cas9-directed disruption of wc-2 leads to the absence of fruiting body development in Pleurotus ostreatus.

Light, particularly blue light, is a key environmental factor that induces fruiting in certain agaricomycetes. In this study, we characterized mutant strains of Pleurotus ostreatus with disrupted wc-2, which encodes one of the white-collar proteins, Wc-2, to investigate the role of light in fruiting in P. ostreatus. We introduced two different plasmids containing expression cassettes for Cas9 and two different gRNAs targeting wc-2 separately into the dikaryotic P. ostreatus strain PC9×#64. Among the 11 dikaryotic hygromycin-resistant transformants, six strains did not form fruiting bodies. Genomic PCR followed by sequencing analysis suggested that all six fruitless strains were dikaryotic wc-2 disruptants. Small aggregate structures were not observed in the dikaryotic wc-2 disruptants grown under light conditions, as in PC9×#64 grown in a red box. These results suggest that Wc-2 is essential for the initiation of blue light-induced fruiting in P. ostreatus.

Pleurotus↗

PubMed2000

Polygalacturonase gene expression in kiwifruit: relationship to fruit softening and ethylene production.

In kiwifruit, much of the softening process occurs prior to the respiratory climacteric and production of ethylene. This fruit therefore represents an excellent model system for dissecting the process of softening in the absence of endogenous ethylene production. We have characterized the expression of three polygalacturonase (PG) cDNA clones (CkPGA, B and C) isolated from fruit of Actinidia chinensis. Expression of CkPGA and B was detected by northern analysis only in fruit producing endogenous ethylene, and by RT-PCR in other tissues including flower buds, petals at anthesis, and senescent petals. CkPGA promoter fragments of 1296, 860 and 467 bp fused to the beta-glucuronidase (uidA) reporter gene directed fruit-specific gene expression during the climacteric in transgenic tomato. CkPGC gene expression was observed in softening fruit, and reached maximum levels (50-fold higher than for CkPGA and B) as fruit passed through the climacteric. However, expression of this gene was also readily detected during fruit development and in fruit harvested prior to the onset of softening. Using RT-PCR, expression of CkPGC was also detected at low levels in root tips and in senescent petals. These results suggest that PG expression is required not only during periods of cell wall degeneration, but also during periods of cell wall turnover and expansion.

Amino Acid Sequence↗

PubMed1992

An Antisense Pectin Methylesterase Gene Alters Pectin Chemistry and Soluble Solids in Tomato Fruit.

Pectin methylesterase (PME, EC 3.1.11) demethoxylates pectins and is believed to be involved in degradation of pectic cell wall components by polygalacturonase in ripening tomato fruit. We have introduced antisense and sense chimeric PME genes into tomato to elucidate the role of PME in fruit development and ripening. Fruits from transgenic plants expressing high levels of antisense PME RNA showed <10% of wild-type PME enzyme activity and undetectable levels of PME protein and mRNA. Lower PME enzyme activity in fruits from transgenic plants was associated with an increased molecular weight and methylesterification of pectins and decreased levels of total and chelator soluble polyuronides in cell walls. The fruits of transgenic plants also contained higher levels of soluble solids than wild-type fruits. This trait was maintained in subsequent generations and segregated in normal Mendelian fashion with the antisense PME gene. These results indicate that reduction in PME enzyme activity in ripening tomato fruits had a marked influence on fruit pectin metabolism and increased the soluble solids content of fruits, but did not interfere with the ripening process.

Journal Article↗

PubMed2003

Differential expression of seven alpha-expansin genes during growth and ripening of pear fruit.

Seven cDNAs, designated PcExp1 to PcExp7, encoding expansin homologues, were isolated from mature pear fruit and their expression profiles were investigated in ripening fruit and other tissues, and in response to ethylene. Accumulation of PcExp2, -3, -5 and -6 mRNA increased markedly with fruit softening and then declined at the over-ripe stage. Treatment of fruit at an early ripening stage with 1-methylcyclopropene (MCP), an inhibitor of ethylene action, suppressed ethylene biosynthesis, fruit softening and the accumulation of the expansin mRNAs. Conversely, propylene treatment at the preclimacteric stage induced accumulation of the same four expansin genes, as well as ethylene production and fruit softening. The expression patterns correlated with alteration in the rate and extent of fruit softening. The abundance of PcExp1 mRNA increased at the late expanding phase of fruit development and further increased during ripening, whereas PcExp4 mRNA levels were constant throughout fruit growth and ripening. The MCP and propylene treatments had little effect on PcExp1 and PcExp4 expression. PcExp7 was expressed in young but not mature fruit. PcExp4 and PcExp6 mRNA was also detected in flowers. The accumulation of PcExp4, -5, -6 and -7 mRNA was more abundant in young growing tissues, but not in fully expanded tissues, suggesting roles for these genes in cell expansion. These results demonstrate that characteristically, multiple expansin genes show differential expression and hormonal regulation during pear fruit development and at least six expansins show overlapping expression during ripening.

Journal Article↗

PubMed2001

Limited carbohydrate availability as a potential cause of fruit abortion in Rubus chamaemorus.

Fruit abortion can be caused by a range of abiotic and biotic factors. To gain a better understanding of the causes of the high fruit abortion frequency in cloudberry (Rubus chamaemorus L.), we manipulated different sources of carbon, that is, leaves and rhizome. We also manipulated flower number to see if competition between floral ramets explained fruit abortion in cloudberry. Reducing the number of flowers had no impact on fruit abortion frequency. In fact, the species forms an extensive rhizome network with only a few ramets per clone and competition between floral ramets is unlikely. Ramet defoliation had limited impact on fruit abortion, but successful fruit development was affected by rhizome length. The longer the rhizome, the higher the chances to mature a fruit. These results suggest that current photoassimilate production by the reproductive ramet alone is insufficient to insure fruit development. Carbon can come from other ramets but distances are usually high between ramets. Fruit production might thus depend on the use of stored carbohydrates in the rhizome to balance insufficient photosynthetic contribution during fruit production.

Journal Article↗

PubMed1993

Isolation and characterization of fruit vacuolar invertase genes from two tomato species and temporal differences in mRNA levels during fruit ripening.

To determine the relationship between invertase gene expression and glucose and fructose accumulation in ripening tomato fruit, fruit vacuolar invertase cDNA and genomic clones from the cultivated species, Lycopersicon esculentum cv. UC82B, and a wild species, Lycopersicon pimpinellifolium, were isolated and characterized. The coding sequences of all cDNA clones examined are identical. By comparison to the known amino acid sequence of mature L. esculentum fruit vacuolar invertase, a putative signal sequence and putative amino-terminal and carboxy-terminal propeptides were identified in the derived amino acid sequence. Of the residues 42% are identical with those of carrot cell wall invertase. A putative catalytic site and a five-residue motif found in carrot, yeast, and bacterial invertases are also present in the tomato sequence. Minor differences between the nucleotide sequences of the genomic clones from the two tomato species were found in one intron and in the putative regulatory region. The gene appears to be present in one copy per haploid genome. Northern analysis suggests a different temporal pattern of vacuolar invertase mRNA levels during fruit development in the two species, with the invertase mRNA appearing at an earlier stage of fruit development in the wild species. Nucleotide differences found in the putative regulatory regions may be involved in species differences in temporal regulation of this gene, which in turn may contribute to observed differences in hexose accumulation in ripening fruit.

Amino Acid Sequence↗

PubMed2006

Tomato Expression Database (TED): a suite of data presentation and analysis tools.

The Tomato Expression Database (TED) includes three integrated components. The Tomato Microarray Data Warehouse serves as a central repository for raw gene expression data derived from the public tomato cDNA microarray. In addition to expression data, TED stores experimental design and array information in compliance with the MIAME guidelines and provides web interfaces for researchers to retrieve data for their own analysis and use. The Tomato Microarray Expression Database contains normalized and processed microarray data for ten time points with nine pair-wise comparisons during fruit development and ripening in a normal tomato variety and nearly isogenic single gene mutants impacting fruit development and ripening. Finally, the Tomato Digital Expression Database contains raw and normalized digital expression (EST abundance) data derived from analysis of the complete public tomato EST collection containing >150,000 ESTs derived from 27 different non-normalized EST libraries. This last component also includes tools for the comparison of tomato and Arabidopsis digital expression data. A set of query interfaces and analysis, and visualization tools have been developed and incorporated into TED, which aid users in identifying and deciphering biologically important information from our datasets. TED can be accessed at http://ted.bti.cornell.edu.

Databases, Genetic↗

PubMed2006

Cyclin-dependent kinase (CDK) inhibitors regulate the CDK-cyclin complex activities in endoreduplicating cells of developing tomato fruit.

The jelly-like locular (gel) tissue of tomato fruit is made up of large thin-walled and highly vacuolized cells. The development of the gel tissue is characterized by the arrest of mitotic activities, the inhibition of cyclin-dependent kinase A (CDKA) activity, and numerous rounds of nuclear DNA endoreduplication. To decipher the molecular determinants controlling these developmental events, we investigated the putative involvement of CDK inhibitors (p27(Kip)-related proteins, or KRPs) during the endoreduplication process. Two cDNAs, LeKRP1 and LeKRP2, encoding tomato CDK inhibitors were isolated. The LeKRP1 and LeKRP2 transcript expression was shown to be enhanced in the differentiating cells of the gel undergoing endoreduplication. At the translational level, LeKRP1 was shown to accumulate in the gel tissue and to participate in the inhibition of the CDK-cyclin kinase activities occurring in endoreduplicating cells of the gel tissue. We here propose that LeKRP1 participates in the control of both the cell cycle and the endoreduplication cycle.

Amino Acid Sequence↗

PubMed1999

Ochratoxin A in dried vine fruit: method development and survey.

A method is described for the determination of concentrations of the mycotoxin ochratoxin A in dried vine fruits (currants, raisins and sultanas) using acidic methanolic extraction, immunoaffinity chromatography clean-up and HPLC determination. The limit of detection was estimated as 0.2 microgram/kg, and recoveries of 63-77% were achieved at 5 micrograms/kg. HPLC-mass spectrometric confirmation of the identity of ochratoxin was obtained. Ochratoxin A and aflatoxins were determined in 60 samples of retail dried vine fruits purchased in the United Kingdom. Ochratoxin A was found in excess of 0.2 microgram/kg in 19 of 20 currant, 17 of 20 sultana and 17 of 20 raisin samples examined, an overall incidence of 88%. The maximum level found was 53.6 micrograms/kg. No aflatoxin was found in any sample analysed, using a method with a detection limit of 0.2 microgram/kg for each of aflatoxin B1, B2, G1 and G2.

Aflatoxins↗

PubMed2005

Enhancer-binding proteins with a forkhead-associated domain and the sigma54 regulon in Myxococcus xanthus fruiting body development.

In response to starvation, Myxococcus xanthus initiates a developmental program that results in the formation of spore-filled, multicellular fruiting bodies. Many developmentally regulated genes in M. xanthus are transcribed from sigma(54) promoters, and these genes require enhancer-binding proteins. Here we report the finding of an unusual group of 12 genes encoding sigma(54)-dependent enhancer-binding proteins containing a forkhead-associated (FHA) domain as their N-terminal sensory domain. FHA domains in other proteins recognize phosphothreonine residues. An insertion mutation in one of these genes, Mx4885, caused a cell autonomous aggregation and sporulation defect. In-frame deletion mutants showed that the FHA domain is necessary for proper Mx4885 function. The altered pattern of developmental gene expression in the mutant implied that Mx4885 is on the pathway of response to the morphogenetic C-signal. Immunoblots specific for C-signal and FruA imply that the site of Mx4885 action is downstream of FruA synthesis on the C-signal transduction pathway. Mx4885 may help to coordinate the level of intracellular phosphorylated FruA (FruA-P) with the level of C-signal displayed on the signal donor cell. Because FHA domains respond to phosphothreonine-containing proteins, these results suggest a regulatory link to the abundant Ser/Thr protein kinases in M. xanthus.

Amino Acid Sequence↗

PubMed1987

Sucrose Metabolism in Netted Muskmelon Fruit during Development.

Sugar content and composition are major criteria used in judging the quality of netted muskmelon (Cucumis melo L. var reticulatus) fruit. Sugar composition and four enzymes of sucrose metabolism were determined in ;Magnum 45' muskmelon fruit at 10-day intervals beginning 10 days after pollination (DAP) until full-slip (35 DAP). Sugar content increased in both outer (green) mesocarp and inner (orange) mesocarp between 20 and 30 DAP. The major proportion of total increase in sugar was attributed to sucrose accumulation. The large increase in sucrose relative to glucose and fructose was accompanied by a dramatic decrease in acid invertase activity, which was highest in both tissues at 10 and 20 DAP, and increases in sucrose phosphate synthase (SPS) and sucrose synthase activities. The green tissue had a lower proportion of total sugar as sucrose, greater invertase activity, and less SPS activity than the orange tissue. Changes in relative sucrose content were highly correlated with changes in enzyme activity. The results strongly suggest that increases in the proportion of sucrose found in melon fruit were associated with a decline in acid invertase activity and an increase in SPS activity approximately 10 days before full-slip. Therefore, these enzymes apparently play a key role in determining sugar composition and the quality of muskmelon fruit.

Journal Article↗

PubMed1992

Sucrose Synthase in Wild Tomato, Lycopersicon chmielewskii, and Tomato Fruit Sink Strength.

Here it is reported that sucrose synthase can be readily measured in growing wild tomato fruits (Lycopersicon chmielewskii) when suitable methods are adopted during fruit extraction. The enzyme also was present in fruit pericarp tissues, in seeds, and in flowers. To check for novel characteristics, the wild tomato fruit sucrose synthase was purified, by (NH(4))(2)SO(4) fraction and chromatography with DE-32, Sephadex G-200, and PBA-60, to one major band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The following characteristics were obtained: native protein relative molecular weight 380,000; subunit relative molecular weight 89,000; K(m) values with: sucrose 53 millimolar, UDP 18.9 micromolar, UDP-glucose 88 micromolar, fructose 8.4 millimolar; pH optima between 6.2 to 7.3 for sucrose breakdown and 7 to 9 for synthesis; and temperature optima near 50 degrees C. The enzyme exhibited a high affinity and a preference for uridylates. The enzyme showed more sensitivity to divalent cations in the synthesis of sucrose than in its breakdown. Sink strength in tomato fruits also was investigated in regard to sucrose breakdown enzyme activities versus fruit weight gain. Sucrose synthase activity was consistently related to increases in fruit weight (sink strength) in both wild and commercial tomatoes. Acid and neutral invertases were not, because the published invertase activity values were too variable for quantitative analyses regarding the roles of invertases in tomato fruit development. In rapidly growing fruits of both wild and commercially developed tomato plants, the activity of sucrose synthase per growing fruit, i.e. sucrose synthase peak activity X fruit size, was linearly related to final fruit size; and the activity exceeded fruit growth and carbon import rates by at least 10-fold. In mature, nongrowing fruits, sucrose synthase activities approached nil values. Therefore, sucrose synthase can serve as an indicator of sink strength in growing tomato fruits.

Journal Article↗

PubMed2005

Virus-induced gene silencing in tomato fruit.

Virus-induced gene silencing (VIGS) is a powerful tool for the study of gene function in plants. Here we report that either by syringe-infiltrating the tobacco rattle virus (TRV)-vector into the surface, stem or carpopodium of a tomato fruit attached to the plant or by vacuum-infiltrating into a tomato fruit detached from the plant, TRV can efficiently spread and replicate in the tomato fruit. Although VIGS can be performed in tomato fruit by all of the means mentioned above, the most effective method is to inject the TRV-vector into the carpopodium of young fruit attached to the plant about 10 days after pollination. Several reporter genes related to ethylene responses and fruit ripening, including LeCTR1 and LeEILs genes, were also successfully silenced by this method during fruit development. In addition, we found that the silencing of the LeEIN2 gene results in the suppression of tomato fruit ripening. The results of our study indicate that the application of VIGS techniques by the described methods can be successfully applied to tomato fruit and is a valuable tool for studying functions of the relevant genes during fruit developing.

Fruit↗

PubMed2005

Larval competition in weevils Revena rubiginosa (Coleoptera: Curculionidae) preying on seeds of the palm Syagrus romanzoffiana (Arecaceae).

Inter- and intraspecific local resource competition may lead to the selection of specific adaptive individual characteristics to overcome interference competition. A highly selective scenario is predictable for interference competition among seed preying weevil larvae that live in and feed upon a single host seed. This scenario is found in Syagrus romanzoffiana palm seeds which are predated by Revena rubiginosa (Curculionidae) larvae. Although multiple infestation of one seed by weevil larvae can occur, invariably only one individual survives and develops in each host seed. A strong competition between the first instar larvae in a restricted window of host fruit development stages leads to physical interactions of conspecifics by ovicide or direct fighting using falcate mandibles. The occurrence of this type of mandible is synchronized with fruit development and restricted to instars with probable competition, as infestation occurs only while the endocarp is soft. Only after lignification of the endocarp the larva changes into the next instar. Mandibles of subsequent instars differ markedly from those of the first instar. The new mandibles can scrape the solid endosperm but are unable to perforate and kill conspecifics. These findings give strong evidence for the selective pressure of intraspecific competition, where special behaviour, mandible morphology and synchronization of its changes with the seed development contribute to individual benefit that involves the killing of conspecifics, since one host seed can only maintain a single larva throughout its complete development.

Animals↗

PubMed1991

Cell-cell interactions that direct fruiting body development in Myxococcus xanthus.

The soil bacterium, Myxococcus xanthus initiates a developmental program when nutrients are limited. This results in the formation of a multicellular fruiting body structure filled with differentiated, environmentally resistant spores. At least four cell-cell signals, cell motility, and aggregation functions are required for the completion of fruiting body formation.

Bacterial Proteins↗

PubMed1999

Gene encoding polygalacturonase inhibitor in apple fruit is developmentally regulated and activated by wounding and fungal infection.

A cDNA encoding polygalacturonase-inhibiting protein (PGIP) from mature apple fruit has been cloned and characterized. The open reading frame encodes a polypeptide of 330 amino acids, in which 24 amino acids at the N-terminus comprise the signal peptide. Apple PGIP contains 10 imperfect leucine-rich repeat sequence motifs averaging 24 amino acids in length. In addition to the 1.3 kb PGIP transcript, the cloned cDNA also hybridized to RNA molecules with sizes of 3.2 and 5.0 kb. Genomic DNA analysis revealed that the apple PGIP probably belongs to a small family of genes. PGIP transcript levels varied in fruit collected at different maturities, suggesting the gene is developmentally regulated. Very high PGIP transcript levels were detected in decayed areas and the tissue adjacent to the inoculation sites of Penicillium expansum and Botrytis cinerea. However, no increase in the amount of PGIP transcript in tissue distant from the decayed region was observed. Wounding on fruit also induced PGIP gene expression but to a much lessser extent when compared with decayed areas. After storage at 0 degrees C for 1 month, the abundance of PGIP transcript in ripe fruit was substantially increased. The PGIP gene in immature and ripe fruit was rapidly up-regulated by fungal infections, while in stored fruit the induction was very limited and concurred with an increase of fruit susceptibility to fungal colonization. Since PGIP gene expression is regulated by fruit development and responds to wounding, fungal infection and cold storage, these observations suggest that apple PGIP may have multiple roles during fruit development and stress response.

Amino Acid Sequence↗

PubMed2005

Identification of oligomers in polyethyleneterephthalate bottles for mineral water and fruit juice. Development and validation of a high-performance liquid chromatographic method for the determination of first series cyclic trimer.

Cyclic oligomers were identified in PET bottles used for mineral water and fruit juice using MS and (1)H and (13)C NMR: a first series cyclic trimer, a first series cyclic tetramer, a first series cyclic dimmer and a second series cyclic trimer. An analytical method to determine first series cyclic trimer in these bottles was developed and validated, using HPLC. The first series cyclic trimer levels were 316-462 mg/100g of PET bottle.

Beverages↗