associated with organic acids, bitterness is often the result of phenolic compounds, saltiness is attributable to sodium or potassium, and sweetness is the result of sugars, including fructose, glucose, and sucrose ( Sims and Golaszewski, 2003 ). Sugars not
Kyle M. VandenLangenberg, Paul C. Bethke, and James Nienhuis
Margarita Pérez-Jiménez, Alfonso Guevara-Gázquez, Antonio Carrillo-Navarro, and José Cos-Terrer
given a central role. Sucrose, fructose, glucose, and sorbitol are the most commonly used sugars used as carbon source and osmotic stabilizer ( Scozzoli and Pasini, 1991 ), although their concentration is more important for the osmolarity of the medium
Alejandra Guadalupe Zamora-Solís, Marcelino Bazan-Tene, Javier Farias-Larios, Jose Gerardo López-Aguirre, and Jaime Molina-Ochoa
Distribution of salinity and sodicity through the world is around 80 thousand million km2. To this quantity, we must add 10 million ha of irrigated lands that are abandoned each year due to such adverse effects on irrigation as salinity and/or alkalinity. Easily available substrates, such as glucose, increase the microbial activity to imprpove soils; for example, pH decreases because of a high production of some metabolites, such as carboxylic acids and hydro phenolics group. We carried out a study to evaluate the effect of glucose application on tomato plant (Lycopersicum esculentum Mill.) growth in saline soil. The experiment was done under greenhouse conditions. Soil samples were taken from 0–20-cm depth at the “El Chococo” ranch (lat. 18°47'N; long. 103°55'W). Treatments imposed were: 2% (T1), 4% (T2), and 6% (T3) glucose and a control without glucose (T0). Soil with treatments was incubated at ambient temperature for 40 days. Tomato seeds were germinated for 30 days and later transplanted to plastic bags that contained treatments. After transplant, tomato plants were grown for 40 days and then evaluated for plant height, dry and fresh weight, aerial and radicular biomass, and foliar area. Treatments were distributed under randomized design, and Tukey's (0.05) separation means were done. When the glucose percentage was increased, the soil pH decreased 8.50, 8.0, 7.70, and 7.60 in T0, T1, T2, and T3, respectively, but electrical conductivity increased. The highest values of parameters evaluated in plants were measured in treatment T3, and all the plants died in treatment (0).
David B. Rubino
Segregating progenies from controlled pollinations of Eustoma grandiflorum Griseb. were investigated to determine the inheritance of diaphorase (DIA) and glucoses-phosphate isomerase (GPI) isozymes. Phenotypic data supported the hypotheses that DIA1 is tetrameric and is controlled by a single locus with two alleles (Dia1-1 and Dia1-2) and that GPI1 is dimeric and also is controlled by a single locus with two alleles (Gpi1-1 and Gpi1-2). Examination of isozyme phenotypes for over 70 cultivars of E. grandiflorum revealed polymorphism for DIA1 and GPI1. These isozymes may be useful for marker-assisted selection and cultivar identification.
David B. Rubino
Segregating lisianthus [Eustoma grandiflorum (Griseb.) Shinn.] progeny were evaluated to determine the inheritance of esterase (EST), diaphorase (DIA), and glucose-6-phosphate isomerase (GPI) isozymes. Phenotypic data supported the hypotheses that EST is monomeric and controlled by one locus (Est1) with at least three alleles, DIA is tetrameric and controlled by one locus (Dia2) with at least two alleles, and GPI is controlled by one locus (Gpil) with at least two alleles. The structure of the GPI isozyme could not be inferred from banding patterns. Joint segregation analyses indicated that the three loci segregate independently. These three isozymes are the first simply inherited, unlinked biochemical markers identified in lisianthus. These marker loci will be useful for genetic studies, breeding, and germplasm characterization.
Rui Zhou and Lailiang Cheng
Apple leaf ADP-glucose pyrophosphorylase was purified over 1400-fold to apparent homogeneity with a specific activity of 58.9 units per mg of protein. The enzyme was activated by 3-phosphoglycerate (PGA) and inhibited by inorganic phosphate (Pi) in the ADPG synthesis direction. In the pyrophosphorolysis direction, however, high concentrations of PGA (>2.5 mm) inhibited the enzyme activity. The enzyme was resistant to thermal inactivation with a T0.5 (temperature at which 50% of the enzyme activity is lost after 5 min of incubation) of 52 °C. Incubation with 2 mm PGA or 2 mm Pi increased T0.5 to 68 °C. Incubation with 2 mm dithiothreitol (DTT) decreased T0.5 to 42 °C, whereas inclusion of 2 mm PGA in the DTT incubation maintained T0.5 at 52 °C. DTT-induced decrease in thermal stability was accompanied by monomerization of the small subunits. Presence of PGA in the DTT incubation did not alter the monomerization of the small subunits of the enzyme induced by DTT. These findings indicate that the binding of PGA may have dual functions in regulating apple leaf AGPase activity—activating the enzyme and rendering the enzyme with a conformation more stable to thermal inactivation.
Ya-Ching Chuang and Yao-Chien Alex Chang
·L −1 sucrose, 20 g·L −1 fructose, or 20 g·L −1 glucose, alone or plus 200 mg·L −1 8-HQS; and distilled water as a control ( Table 1 ). These concentrations were chosen according to previous literature ( Ichimura and Korenaga, 1998 ; Islam et al
Mark J. Howieson and Nick Edward Christians
a polymer of fructose with a terminal glucose moiety ( Chatterton et al., 1989 ). Increased catabolism and decreases in levels of fructans have been observed in grasses in response to defoliation ( Morvan-Betrand et al., 2001 ; Prud'homme et al
Wesley Gartner, Paul C. Bethke, Theodore J. Kisha, and James Nienhuis
showed that 80% of the soluble carbohydrate that accumulated in cotyledons was sucrose, with less than 5% each of glucose and fructose ( Patrick and McDonald, 1980 ). Significant accumulation of seed dry weight begins ≈8–12 d after fertilization, stops
Marija Perić, Slavica Dmitrović, Suzana Živković, Biljana Filipović, Marijana Skorić, Ana Simonović, and Slađana Todorović
species. Among carbohydrates used for in vitro cultures, sucrose is the most common, but for some species, other sugars are more suitable. Glucose proved to be a better carbon source for in vitro development of Nepeta rtanjensis ( Mišić et al., 2005 ) as