Overaccumulation of higher polyamines in ripening transgenic tomato fruit revives metabolic memory, upregulates anabolism-related genes, and positively impacts nutritional quality.

Vegetables and fruits are essential components of the human diet as they are sources of vitamins, minerals, and fiber and provide antioxidants that prevent chronic diseases. Our goal is to improve durable nutritional quality of tomato fruit. We developed transgenic tomatoes expressing yeast S-adenosylmethionine decarboxylase (ySAMdc) gene driven by a fruit-specific E8 promoter to investigate the role of polyamines in fruit metabolism.

Isolation of high-quality RNA from apple (Malus domestica) fruit.

It is difficult to isolate sufficient quantities of high-quality RNA from apple fruit. An abundance of polyphenolic compounds and polysaccharides and a relatively low concentration of RNA in the fruit tissue create conditions that hamper RNA isolation when standard techniques are used. We have developed two RNA isolation methods that include an initial homogenization and extraction with acetone or ethanol.

Molecular characterization of a tomato endo-beta-1,4-glucanase gene expressed in mature pistils, abscission zones and fruit.

A cDNA (TAC1) and genomic clone (cel5) encoding an endo-beta-1,4-glucanase (EGase) were identified from tomato (Lycopersicon esculentum Mill., cv. Rutgers).

Isolation of a zeta class wheat glutathione S-transferase gene.

A new Zeta class glutathione S-transferases (GST) gene, pGST, has been cloned from wheat for the first time by the differential display PCR (DD-PCR) method. The genomic sequence of pGST, TA-GSTZ1, contains nine exons that encode a polypeptide of 213 amino acids and eight introns. The deduced amino acid sequence of TA-GSTZ1 as well as the exon:intron placement are more similar to the GSTs of the Zeta class than to the two wheat GSTs reported earlier.

Cloning and characterization of a rhamnogalacturonan hydrolase gene from Botrytis cinerea.

Rhamnogalacturonan hydrolase (Rgase A) cleaves alpha 1--2 linkages between rhamnosyl and galacturonosyl residues in pectin. A 1.9 kb RGase A cDNA clone (BCRHGA) was isolated from a B.

Three different polygalacturonases are expressed in tomato leaf and flower abscission, each with a different temporal expression pattern.

Abscission, or organ separation, is accompanied by a marked increase in hydrolases, which are responsible for the degradation of the middle lamella and the loosening of the primary cell wall surrounding cells in the separation layer. We recently reported on the cloning of a tomato (Lycopersicon esculentum) polygalacturonase (PG) cDNA, TAPG1, expressed during leaf and flower abscission. In addition to TAPG1, we have cloned two more PG cDNAs (TAPG2 and TAPG4) that are also expressed during leaf and flower abscission.

Suppression of cellulase and polygalacturonase and induction of alcohol dehydrogenase isoenzymes in avocado fruit mesocarp subjected to low oxygen stress.

Expression of polygalacturonase and cellulase, two hydrolytic enzymes of avocado (Persea americana, cv Hass) fruit which are synthesized de novo during ripening, and alcohol dehydrogenase, a known anaerobic protein, were studied under different O(2) regimes. Low O(2) concentrations (2.5-5.

Visualization of acid phosphatase activity on nitrocellulose filters following electroblotting of polyacrylamide gels.

A method for visualizing acid phosphatase isoenzymes by activity staining on nitrocellulose filters after electroblotting of proteins fractionated on nondenaturing polyacrylamide gels is described. Reproducible results were obtained when 25 mM Tris-192 mM glycine was used as the transfer buffer instead of 0.7% acetic acid, 50 mM sodium acetate, pH 4, or 0.

Hydrolytic Enzyme Activities and Protein Pattern of Avocado Fruit Ripened in Air and in Low Oxygen, with and without Ethylene.

The effect of 2.5% O(2) atmosphere with and without ethylene on the activities of hydrolytic enzymes associated with cell walls, and total protein profile during ripening of avocado fruits (Persea americana Mill., cv Hass) were investigated.

Changes in Sugars, Enzymic Activities and Acid Phosphatase Isoenzyme Profiles of Bananas Ripened in Air or Stored in 2.5% O(2) with and without Ethylene.

This study investigates the effect of 2.5% O(2), both alone and in combination with ethylene, on respiration, sugar accumulation and activities of pectin methylesterase and acid phosphatase during ripening of bananas (Musa paradisiaca sapientum). In addition, the changes in the phosphatase isoenzyme profiles are also analyzed.

Characterization of the Stimulation of Ethylene Production by Galactose in Tomato (Lycopersicon esculentum Mill.) Fruit.

We have characterized the stimulation of ethylene production by galactose in tomatoes (Lycopersicon esculentum Mill.). The effect of concentration was studied by infiltrating 0, 4, 40, 100, 200, 400, or 800 micrograms galactose for each gram of fresh fruit weight into mature green ;Rutgers' fruit.

Enhancement by ethylene of cellulysin-induced ethylene production by tobacco leaf discs.

Cellulysin-induced ethylene production in tobacco (Nicotiana tabacum L.) leaf discs was enhanced several-fold by prior exposure of the leaf tissue to ethylene. This enhancement in the response of the tissue to Cellulysin increased rapidly during 4 and 8 hours of pretreatment with ethylene and resulted from greater conversion of methionine to ethylene.

Some Characteristics of the System Converting 1-Aminocyclopropane-1-carboxylic Acid to Ethylene.

The rate of C(2)H(4) production in plant tissue appears to be limited by the level of endogenous 1-aminocyclopropane-1-carboxylic acid (ACC). Exogenous ACC stimulated C(2)H(4) production considerably in plant tissues, but this required 10 to 100 times the endogenous concentrations of ACC before significant increases in C(2)H(4) production were observed. This was partially due to poor penetration of ACC into the tissues.

Effects of Cyanide and Ethylene on the Respiration of Cyanide-sensitive and Cyanide-resistant Plant Tissues.

The effects of cyanide and ethylene, respectively, were studied on the respiration of a fully cyanide-sensitive tissue-the fresh pea, a slightly cyanide-sensitive tissue-the germinating pea seedling, and a cyanide-insensitive tissue-the cherimoya fruit. Cyanide inhibition of both fresh pea and pea seedling respiration was attended by a conventional Pasteur effect where fermentation was enhanced with an accumulation of lactate and ethanol and a change in the level of glycolytic intermediates indicative of the activation of phosphofructokinase and pyruvate kinase accompanied by a sharp decline in ATP level. In these tissues, ethylene had little or no effect on the respiration rate, or on the level of glycolytic intermediates or ATP.

The mechanism of ethylene and cyanide action in triggering the rise in respiration in potato tubers.

Ethylene and cyanide induce a sharp increase in respiration in potato tubers (Solanum tuberosum, var. Russet) attended by changes in the glycolytic intermediates which indicate that both gases enhance glycolysis. The level of sucrose also increases in response to both treatments.

Similarities between the Actions of Ethylene and Cyanide in Initiating the Climacteric and Ripening of Avocados.

A continuous exposure of intact avocados (Persea americana) to 400 mul/l of cyanide results in a rapid increase in the rate of respiration, followed by a rise in ethylene production, and eventual ripening. The pattern of changes in the glycolytic intermediates glucose 6-phosphate, fructose diphosphate, 3-phosphoglyceric acid, and phosphoenolpyruvate during the rapid rise in respiration in both ethylene and cyanide-treated fruits is similar to that found in fruits made anaerobic where a 2.3- to 3-fold increase in the rate of glycolysis is observed.

Effects of cycloheximide, D-threo-chloramphenicol, erythromycin and actinomycin D on De-novo synthesis of cytoplasmic and mitochondrial proteins in the cotyledons of germinating pea seeds.

Inhibitors of, and radioactive substrates for, protein synthesis were introduced into germinating pea (Pisum sativum L.) seeds, and protein synthesis was allowed to proceed in vivo. Subsequent analyses of subcellular fractions showed the following: Cycloheximide strongly inhibited the incorporation of [(14)C]leucine into both mitochondrial and cytoplasmic proteins.

Use of dextran-40 gradients for separation of pea cotyledon mitochondria into different fractions.

A crude pea (Pisum sativum L. var. Homesteader) mitochrondrial preparation was divided into two equal parts.