An official website of the United States government
Here’s how you know
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
... The ATPase activity and fluorescence of ribulose-1,5-bisphosphate carboxylase oxygenase (Rubisco) activase were determined over a range of MgCl2, KCl, and activase concentrations. Both salts promoted ADP release from ATP and intrinsic fluorescence enhancement by adenosine 5'-[gamma-thio] triphosphate, but Mg2+ was about 10 times more effective than K+. ATPase and fluorescence enhancement both incr ...
... Soybean plants (Glycine max L. Merr) were grown with 100 micromolar S and 15 mM N and studied with respect to S allocation during grain development. The grains accounted for 87% of the S taken up after d 42, the balance coming from internal redistribution of S from leaves and pods. Detailed studies of the leaves, pods, and grains associated with leaf axils 6 and 7 showed that sulfate accumulated i ...
... Using dichromatic radiation, we show that the actions of phytochromes A and B (phyA and phyB) in Arabidopsis thaliana are antagonistic in mediating red and far-red radiation effects on seedling de-etiolation and yet act in a complementary manner to regulate de-etiolation, irrespective of spectral composition. At low phytochrome photoequilibria inhibition of hypocotyl extension was strong, because ...
... The potential role of antioxidant enzymes in protecting maize (Zea mays L.) seedlings from chilling injury was examined by analyzing enzyme activities and isozyme profiles of chilling-susceptible (CO 316) and chilling-tolerant (CO 328) inbreds. Leaf superoxide dismutase (SOD) activity in CO 316 was nearly one-half that of CO 328, in which the high activity was maintained during the chilling and po ...
... By comparing growth under five different temperature and irradiance regimes (20 degrees C and 800, 250, and 50 micromoles m-2 s-1 and 5 degrees C and 250 and 50 micromoles m-2 s-1), we have examined the effects of light, temperature, and the relative reduction state of photosystem II on plant morphology, freezing tolerance (lethal temperature at which freezing injury occurs [LT50]), transcript lev ...
Glycine max; cell growth; stems; developmental stages; water stress; cells; xylem; roots; hydraulic conductivity; root water potential; measurement
Abstract:
... Cell enlargement depends on a growth-induced difference in water potential to move water into the cells. Water deficits decrease this potential difference and inhibit growth. To investigate whether the decrease causes the growth inhibition, pressure wasapplied to the roots of soybean (Glycine max L. Merr.) seedlings and the growth and potential difference were monitored in the stems. In water-limi ...
... A glycopeptide elicitor prepared from germ tubes of the rust fungus Puccinia graminis Pers. f. sp. tritici Erikss. & Henn (Pgt),as well as chitin oligosaccharides, chitosan, and methyl jasmonate (MJ) stimulated lipoxygenase (LOX) activity (E.C. 1.13.11.12) in wheat (Triticum aestivum) leaves. Immunoblot analysis using anti-LOX antibodies revealed the induction of 92- and 103-kD LOX species after P ...
... Quinone oxidoreductase activities dependent on pyridine nucleotides are associated with the plasma membrane (PM) in zucchini (Cucurbita pepo L.) hypocotyls. In the presence of NADPH, lipophilic ubiquinone homologs with up to three isoprenoid units were reduced by intact PM vesicles with a Km of 2 to 7 micromolars. Affinities for both NADPH and NADH were similar (Km of 62 and 51 micromolars, respec ...
... Rice (Oryza sativa L.) plants with decreased ribulose-1,5-bisphosphate carboxylase (Rubisco) were obtained by transformation with the rice rbcS antisense gene under the control of the rice rbcS promoter. The primary transformants were screened for the Rubisco to leaf N ratio, and the transformant with 65% wild-type Rubisco was selected as a plant set with optimal Rubisco content at saturating CO2 ...
... We characterized the effect of water stress on cell division rates within the meristem of the primary root of maize (Zea mays L.) seedlings. As usual in growth kinematics, cell number density is found by counting the number of cells per small unit length of the root; growth velocity is the rate of displacement of a cellular particle found at a given distance from the apex; and the cell flux, repre ...
Helianthus annuus; Brassica napus; measurement; chemical degradation; dose response; jasmonic acid; gene expression; Triticum aestivum; Nicotiana tabacum; esters; stereochemistry; enzyme activity; chemical structure; seed germination; transgenic plants; cotyledons; proteinase inhibitors; reporter genes; chemical constituents of plants; chlorophyll; beta-glucuronidase
Abstract:
... The importance of the two chiral centers at C-3 and C-7 in the molecular structure of jasmonic acid in plant responses was investigated. We separated methyl jasmonate (MeJA) into (3R)- and (3S)-isomers with a fixed stereochemistry at C-3, but epimerization at C-7 is possible. The four isomers of the nonepimerizable analog 7-methyl MeJA were synthesized. These six esters and their corresponding aci ...
... The influence of various environmental factors on biomass partitioning between shoots and roots in transgenic tobacco (Nicotiana tabacum) plants expressing the movement protein (MP) of tobacco mosaic virus (TMV) was investigated. TMV-MP-expressing transgenic plants exhibited a root-to-shoot ratio that was approximately 40% below that of transgenic vector control plants. When transgenic plants expr ...
mevalonic acid; biosynthesis; lactones; phenotype; chemical reactions; chemical constituents of plants; developmental stages; Persea americana; ontogeny; enzyme inhibitors; cytokinins; hydroxymethylglutaryl-CoA reductases; abscisic acid; catalytic activity; stigmasterol; metabolites
Abstract:
... The effect of isoprenoid growth regulators on avocado (Persea americana Mill. cv Hass) fruit growth and mesocarp 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) activity was investigated during the course of fruit ontogeny. Both normal and smallfruit phenotypes were used to probe the interaction between the end products of isoprenoid biosynthesis and the activity of HMGR in the metabolic co ...
... Exogenous concentrations of 10 micromolar to 1 mM of the nonprotein amino acid taurine stimulated photosynthate release from the dinoflagellate alga Symbiodinium, which had been freshly isolated from the sea anemone Aiptasia pulchella. Photosynthate release, as induced by taurine and animal extract, was metabolically equivalent at both concentrations in that they (a) stimulated photosynthate relea ...
... Transgenic tobacco (Nicotiana tabacum cv Bel W3) plants were used to test the hypothesis that protection from O3 injury could be conferred by overproduction of ascorbate peroxidase (APX) in the chloroplast. The 10-fold increase in soluble APX activity in the chloroplast was expected to alleviate an implied increase in oxidative potential and prevent damage caused by O3. Three different O3 exposure ...
phytoplankton; protein synthesis; cell growth; nutrient deficiencies; iron; net assimilation rate; electron transfer; stress response; cultured cells; Phaeodactylum tricornutum; metalloproteins; photosynthesis; protein content
Abstract:
... Flavodoxin is a small electron-transfer protein capable of replacing ferredoxin during periods of Fe deficiency. When evaluating the suitability of flavodoxin as a diagnostic indicator for Fe limitation of phytoplankton growth, we examined its expression in two marine diatoms we cultured using trace-metal-buffered medium. Thalassiosira weissflogii and Phaeodactylum tricornutum were cultured in eth ...
... Reproductive and vegetative tissues of the seeded Pineapple cultivars of sweet orange (Citrus sinensis L.) contained the following C-13 hydroxylated gibberellins (GAs): GA53, GA17, GA19, GA20, GA1, GA29, and GA8, as well as GA97, 3-epi-GA1, and several uncharacterized GAs. The inclusion of 3-epi-GA1 as an endogenous substance was based on measurements of the isomerization rates of previously added ...
allene; Zea mays; biosynthesis; seeds; chemical reactions; catalytic activity; jasmonic acid; long chain fatty acids; physicochemical properties; enzyme inhibitors; isomerases; biochemical pathways; oxides; protein composition
Abstract:
... Allene oxide cyclase (AOC; EC 5.3.99.6) catalyzes the cyclization of 12,13(S)-epoxy-9(Z),11,15(Z)-octadecatrienoic acid to 12-oxo-10,15(Z)-phytodienoic acid, the precursor of jasmonic acid (JA). This soluble enzyme was purified 2000-fold from dry corn (Zea mays L.) kernels to apparent homogeneity. The dimeric protein has a molecular mass of 47 kD. Allene oxide cyclase activity was not affected by ...