Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Lactuca sativa”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1999

Initiation and elongation of lateral roots in Lactuca sativa.

Lactuca sativa cv. Baijianye seedlings do not normally produce lateral roots, but removal of the root tip or application of auxin, especially indole-butyric acid, triggered the formation of lateral roots. Primordia initiated within 9 h and were fully developed after 24 h by activating the pericycle cells opposite the xylem pole. The pericycle cells divided asymmetrically into short and long cells. The short cells divided further to form primordia. The effect of root tip removal and auxin application was reversed by 6-benzylaminopurine at concentrations >10(-8) M. The cytokinin oxidase inhibitor N1-(2chloro4pyridyl)-N2-phenylurea also suppressed auxin-induced lateral rooting. The elongation of primary roots was promoted by L-alpha-(2-aminoethoxyvinyl) glycine and silver ions, but only the latter enhanced elongation of lateral roots. The data indicate that the induction of lateral roots is controlled by basipetally moving cytokinin and acropetally moving auxin. Lateral roots appear to not produce ethylene.

Adenine↗
PubMed2002

Toxicity of methyl tert-butyl ether to plants (Avena sativa, Zea mays, Triticum aestivum, and Lactuca sativa).

Influence of methyl tert-butyl ether (MTBE) on the germination of seeds and growth of seedling plants were studied in laboratory experiments. Test plants were wild oats (Avena sativa), sweet corn (Zea mays), wheat (Triticum aestivum), and lettuce (Lactuca sativa). Seed germination, shoot growth, and root growth of plants exposed to different concentrations of MTBE in a moist soil were examined. Seed germination and seedling growth in MTBE-contaminated soil were markedly reduced in all test plants. The median lethal concentration values for seed germination tests and the median effective concentration values for shoot or root growth were calculated. The values for lettuce, wild oats, wheat, and sweet corn were in the range of 18 to 91, 362 to 459, 432 to 751, and 672 to 964 mg MTBE/kg soil as dry weight, respectively. Lettuce was most sensitive to MTBE, followed (in order of decreasing sensitivity) by wild oats, wheat, and sweet corn. Because MTBE can be readily absorbed by plants due to its high solubility in water, plant growth was a more sensitive endpoint than seed germination. Shoot length was more reduced in MTBE-contaminated soil than was the root length, which indicated that MTBE might be transported within the plant from the roots to the shoots.

Absorption↗
PubMed2004

Analgesic and anti-inflammatory activity of Lactuca sativa seed extract in rats.

Lactuca sativa (Lettuce) is a member of Compositae family. In folk medicine of Iran, the seeds of this plant were used for relieving of inflammation and osteodynia. In this study, anti-nociceptive and anti-inflammatory activities of a crude methanol/petroleum ether (70/30, v/v) extract of the seeds have been evaluated. The extract exhibited a time- and dose-dependent analgesic effect in formalin test and also a dose-dependent anti-inflammatory activity in a carrageenan model of inflammation. The extract had no analgesic effect in tail-flick test up to the highest dose used (6 g/kg). No abnormal behavior and lethality was observed by the extract up to 6 g/kg. Preliminary phytochemical analysis showed the presence of triterpenoids, saponins and simple phenols in the extract.

Animals↗
PubMed1998

Study of a case of hypersensitivity to lettuce (Lactuca sativa).

BACKGROUND: Allergic reactions to lettuce (Lactuca sativa) are not too frequent and few cases of systemic adverse reactions after its ingestion have been described. OBJECTIVE: We report a case of clinical sensitization to lettuce on a patient who presented mucocutaneous manifestations after its ingestion, with positive skin tests, histamine release test and serum specific-IgE to lettuce. The allergens responsible for this sensitization were also characterized by means of SDS-PAGE immunoblotting. MATERIALS AND METHODS: We performed skin tests, histamine release test, serum specific IgE determination and CAP inhibition with lettuce and mugwort (Artemisia vulgaris) extracts. An aqueous and enriched lettuce (from loose leaf type) extract was subjected to SDS-PAGE immunoblotting for determination of its IgE-binding components. RESULTS AND CONCLUSIONS: CAP inhibition showed antigenic community between lettuce and mugwort. Four protein bands from the lettuce extracts with molecular weights of 50, 43, 39 and 16 kDa exhibited IgE-binding properties.

Adult↗
PubMed2002

Cloning and expression of sesquiterpene synthase genes from lettuce (Lactuca sativa L.).

Sesquiterpenoid lactones (SLs) from lettuce (Lactuca sativa L.) include constitutive components of latex such as lactucin and the induced phytoalexin, lettucenin A. A redundant primer strategy was used to recover two full length cDNA clones (LTC1 and LTC2) encoding sesquiterpene synthases from a cDNA library derived from seedlings with the red spot disorder, which accumulate phytoalexins. Recombinant enzymes produced from LTC1 and LTC2 in Escherichia coli catalysed the cyclisation of farnesyl diphosphate to germacrene A, potentially an early step in the biosynthesis of SLs. RT-PCR analysis showed LTC1 and LTC2 were expressed constitutively in roots, hypocotyls and true leaves but not in cotyledons. Expression in cotyledons was induced by challenge with the downy mildew pathogen Bremia lactucae in the disease resistant cultivar Diana. Southern hybridisation experiments showed that LTC1 and LTC2 were not part of a multigene family. The germacrene A synthases provide targets for modified expression to generate beneficial modifications to the SL profile in lettuce.

Amino Acid Sequence↗
PubMed1977

Release of Esterase Following Germination of Lettuce Seed (Lactuca sativa L.).

Light-insensitive lettuce seeds, Lactuca sativa L. cv. Great Lakes, release esterases for a period following radicle protrusion. Very little or no enzymes are released prior to 24 hours or after 48 hours of germination. As compared to intact seeds, half-seeds readily release esterases and the release is not affected by far red irradiation. Bulk of the released esterases are derived from the endosperm tissue and presumably exists in the intact seed as a component of the extraembryonic fluid.

Journal Article↗
PubMed2005

Purification and biochemical properties of glutathione S-transferase from Lactuca sativa.

A glutathione S-transferase (GST) from Lactuca sativa was purified to electrophoretic homogeneity approximately 403-fold with a 9.6% activity yield by DEAE-Sephacel and glutathione (GSH)-Sepharose column chromatography. The molecular weight of the enzyme was determined to be approximately 23,000 by SDS-polyacrylamide gel electrophoresis and 48,000 by gel chromatography, indicating a homodimeric structure. The activity of the enzyme was significantly inhibited by ShexylGSH and S-(2,4-dinitrophenyl) glutathione. The enzyme displayed activity towards 1-chloro-2,4-dinitrobenzene, a general GST substrate and high activities towards ethacrynic acid. It also exhibited glutathione peroxidase activity toward cumene hydroperoxide.

Enzyme Inhibitors↗
PubMed2002

Germination and growth of lettuce (Lactuca sativa) at low atmospheric pressure.

The response of lettuce (Lactuca sativa L. cv. Waldmann's Green) to low atmospheric pressure was examined during the initial 5 days of germination and emergence, and also during subsequent growth to vegetative maturity at 30 days. Growth took place inside a 66-l-volume low pressure chamber maintained at 70 kPa, and plant response was compared to that of plants in a second, matching chamber that was at ambient pressure (approximately 101 kPa) as a control. In other experiments, to determine short-term effects of low pressure transients, plants were grown at ambient pressure until maturity and then subjected to alternating periods of 24 h of low and ambient atmospheric pressures. In all treatments the partial pressure of O2 was maintained at 21 kPa (approximately the partial pressure in air at normal pressure), and the partial pressure of CO2 was in the range 66.5-73.5 Pa (about twice that in normal air) in both chambers, with the addition of CO2 during the light phase. With continuous exposure to low pressure, shoot and root growth was at least as rapid as at ambient pressure, with an overall trend towards slightly greater performance at the lower pressure. Dark respiration rates were greater at low pressure. Transient periods at low pressure decreased transpiration and increased dark respiration but only during the period of exposure to low pressure. We conclude that long-term or short-term exposure to subambient pressure (70 kPa) was without detectable detriment to vegetative growth and development.

Atmosphere Exposure Chambers↗
PubMed1981

L-Lactate dehydrogenase from leaves of higher plants. Kinetics and regulation of the enzyme from lettuce (Lactuca sativa L).

1. L-Lactate dehydrogenase from lettuce (Lactuca sativa) leaves was purified to electrophoretic homogeneity by affinity chromatography. 2. In addition to its NAD(H)-dependent activity with L-lactate and pyruvate, the enzyme also catalyses the reduction of hydroxypyruvate and glyoxylate. The latter activities are not due to a contamination of the enzyme preparations with hydroxypyruvate reductase. 3. The enzyme shows allosteric properties that are markedly by the pH. 4. ATP is a potent inhibitor of the enzyme. The kinetic data suggest that the inhibition by ATP is competitive with respect to NADH at pH 7.0 and 6.2. The existence of regulatory binding sites for ATP and NADH is discussed. 5. Bivalent metal cations and fructose 6-phosphate relieve the ATP inhibition of the enzyme. 6. A function of leaf L-lactate dehydrogenase is proposed as a component of the systems regulating the cellular pH and/or controlling the concentration of reducing equivalents in the cytoplasm of leaf cells.

Adenosine Triphosphate↗
PubMedDate not supplied

Antifungal action of latex saps from Lactuca sativa L. and Asclepias curassavica L.

Asclepias curassavica and Lactuca sativa latex saps inhibit the growth of Candida albicans because they degrade a great number of yeasts. This was confirmed by scanning and transmission electron microscopy observations. After a contact of 4 h and 6 h yeasts are deformed and emptied of their cytoplasmic content. Moreover, it appears that these saps, particularly Asclepias, also act on the cell wall: the substances presumed to be responsible for these effects were probably terpens and cardenolids but also enzymes, in particular glucanases.

Antifungal Agents↗
PubMed1996

Molecular analysis of irradiation-induced and spontaneous deletion mutants at a disease resistance locus in Lactuca sativa.

The major cluster of disease resistance genes in lettuce (Lactuca sativa) contains at least nine downy mildew resistance genes (Dm) spanning a genetic distance of 20cM and a physical distance of at least 6 Mb. Nine molecular markers that were genetically tightly linked to Dm3 were used to analyze nine independent deletion mutants and construct a map of the region surrounding Dm3. This analysis identified a linear order of deletion breakpoints and markers along the chromosome. There was no evidence for chromosomal rearrangements associated with the deletions. The region is not highly recombinagenic and the deletion breakpoints provided greater genetic resolution than meiotic recombinants. The region contains a mixture of high-and low-copy number sequences; no single-copy sequences were detected. Three markers hybridized to low-copy-number families of sequences that are duplicated predominantly close to Dm3. This was not true for sequences related to the triose-phosphate isomerase gene; these had been shown previously to be linked to Dm3, as well as to two independent clusters of Dm genes, and elsewhere in the genome. Two spontaneous mutants of Dm3 were identified; several markers flanking Dm3 are absent in one of these two mutants. The stability of the Dm3 region was also studied by analyzing the genotypes of diverse related cultivars. The 1.5 Mb region surrounding Dm3 has remained stable through many generations of breeding with and without selection for Dm3 activity.

Chromosome Mapping↗
PubMed2003

SNP-based codominant markers for a recessive gene conferring resistance to corky root rot (Rhizomonas suberifaciens) in lettuce (Lactuca sativa).

The analysis of F2 progeny and derived F3 families of Lactuca sativa segregating for resistance to corky root rot caused by Rhizomonas suberifaciens permitted the identification of restriction fragment length polymorphism (RFLP) and single nucleotide polymorphism (SNP) markers linked to the recessive resistance gene cor. PCR-based markers were identified by bulked segregant analysis (BSA). Allele-specific primers were generally designed with the 3 terminal base coinciding with an SNP, matching one of the alleles and mismatching the other, and with an additional subterminal 3 base mismatching both alleles. Codominant, robust, and inexpensive molecular markers were obtained that used standardized PCR conditions. Some of the markers could be analyzed in multiple Lactuca mapping populations that did not segregate for disease resistance allowing the cor locus to be located on several maps. The consistent low density of markers around cor in these maps suggests that cor may be in an area with an elevated rate of recombination. Evaluation of these markers in a large sample of cultivars and landraces identified pairs of flanking polymorphic markers that can be used for marker-assisted selection of corky root resistance.

Chromosome Mapping↗
PubMed1985

Interactions between Mild NaCl Stress and Red Light during Lettuce (Lactuca sativa L. cv Grand Rapids) Seed Germination.

The sensitivity of lettuce (Lactuca sativa L. cv Grand Rapids) seeds to red light was reduced by NaCl concentrations which had no effect upon the germination of continuously illuminated seeds. The germination capacity of the seeds was fully restored by increased red light exposures. Indirect evidence indicates that NaCl does not affect the photoconversion of red-absorbing form of phytochrome to the far-red absorbing form of phytochrome. Instead, the increased red light requirements are attributable to increases in the threshold levels of the far-red absorbing form of phytochrome necessary to induce germination and to changes in the slopes of the fluence-response curves. Results also show that the sensitivity of the seeds to NaCl decreased as the time between red light irradiation and the imposition of NaCl stress increased.

Journal Article↗
PubMed2001

Evidence for a tetrameric form of iceberg lettuce (Lactuca sativa L.) polyphenol oxidase: purification and characterization.

Polyphenol oxidase from iceberg lettuce (Lactuca sativa L.) chloroplasts was released from the thylakoid-membrane by sonication, and it was extensively purified to homogeneity as judged by SDS-PAGE. Purification was achieved by ammonium sulfate fractionation, gel-filtration chromatography, and ion-exchange chromatography. Two molecular forms were separated by gel-filtration chromatography with apparent molecular masses of 188 and 49 kDa. Both forms were characterized by sedimentation analysis with S(20,W) values of 10.2 and 4.1 S, respectively. For the high-molecular-weight form purified to homogeneity, denaturing SDS-PAGE indicated a molecular mass of 60 kDa. Thus, from these data we suggest that lettuce polyphenol oxidase is a tetramer of identical subunits.

Ammonium Sulfate↗
PubMed1980

Stabilization of adenine nucleotide ratios at various values by an oxygen limitation of respiration in germinating lettuce (Lactuca sativa) seeds.

The concentrations of adenine nucleotides were determined in germinating lettuce (Lactuca sativa) seeds after transitions from air to hypoxic or anoxic atmospheres. The ratio ATP/ADP and the energy charge were rapidly lowered after the transitions and remained stable at low values for hours. The energy charge in anoxia stabilized at a value close to 0.3. After 24 h in anoxia the energy charge rose rapidly to high values (0.9) when N2 was replaced by air. The metabolic properties of lettuce seeds had then been conversed for hours at low energy charge. In hypoxia the O2 uptake was decreased and the energy charge was stabilized at values intermediate between that in air and that in anoxia. When the O2 partial pressures (pO2) were 5 and 2kPa, the values of O2 uptake were one-third and one-sixth of that in air, and the energy charges were 0.7 and 0.5. These results show that the energy charge is regulated over a wide range of values. The ratio ATP/ADP and the energy charge are indicators of the limitation of metabolic activity by hypoxia.

Adenine Nucleotides↗
PubMed1994

Cell-Wall Autohydrolysis in Isolated Endosperms of Lettuce (Lactuca sativa L.).

Cell walls prepared from the endosperm tissue of hydrated lettuce (Lactuca sativa L.) seeds undergo autohydrolysis. Release of carbohydrates is most rapid (0.4-0.6 [mu]g per endosperm) within the 1st h of incubation in buffer, but substantial autolysis is sustained for at least 10 h. Autolysis is temperature sensitive, and the optimum rate occurs at pH 5. The rate of autolysis increases markedly in the period just prior to radicle emergence. The cell-wall polysaccharide composition in micropylar and lateral endosperm regions differs significantly; the micropylar walls are rich in arabinose and glucose with substantially lower amounts of mannose. Although walls prepared from both micropylar and lateral regions undergo autolysis, micropylar walls release carbohydrates at a higher rate than lateral walls. Autolysis products elute as large polymers when subjected to size-exclusion chromatography, suggesting that endo-enzyme activity is responsible for release of fragments containing arabinose, galactose, mannose, and uronic acids. Arabinose, galactose, mannose, and glucose are also released as monomers. As a function of time, the ratio of polymers to monomers decreases, indicating that exo-enzyme activity is also present. Thermoinhibition or treatment with abscisic acid suppresses germination and reduces the rates of autolysis of walls isolated from the endosperm by about 25%. Treatments that alleviate thermoinhibition (kinetin and gibberellic acid) increase the rates of autolysis by 20 to 30% when compared to thermoinhibited controls.

Journal Article↗
PubMed1986

Role of Ethylene in Lactuca sativa cv ;Grand Rapids' Seed Germination.

Promotion of thermoinhibited (30 degrees C) lettuce (Lactuca sativa cv ;Grand Rapids') seed germination by ethylene is similar to the action of the gas in other hormonal systems. Ethylene was more active than propylene and ethane was inactive. An inhibitor of ethylene production, aminoethoxy-vinylglycine, reduced ethylene evolution and germination. Inhibitors of ethylene action such as, 5-methyl-7-chloro-4-ethoxycarbonylmethoxy-2,1,3-benzothiadiazole, 2,5-norbornadiene, and silver thiosulfate inhibited germination and the effect was reversed by the addition of ethylene to the gas phase. The action of ethylene appears to be due to the promotion of radial cell expansion in the embryonic hypocotyl. The action of N6-benzyladenine and fusiccocin, which also overcome thermoinhibition, appears to be due to a promotion of hypocotyl elongation. None of the germination promoters studied appeared to function by lowering the mechanical resistance of the endosperm to embryonic growth. Data presented here are consistent with the view that ethylene plays a role in lettuce seed germination under thermoinhibited and normal conditions.

Journal Article↗
PubMed2000

Inactivation of DNA replication origins by the cell cycle regulator, trigonelline, in root meristems of Lactuca sativa.

The effects of trigonelline (TRG) on the cell cycle in root meristems of Lactuca sativa L. were examined in the knowledge that TRG is a cell cycle regulator that causes cell arrest in G2, and prevents ligation of replicons in S-phase. The hypothesis was tested that continuous exposure to TRG would perturb DNA replication which, in turn, would lengthen the cell cycle and impair root elongation. Using DNA fibre autoradiography, mean replicon size was 31 and 13 microm in the TRG (3 mM) and control treatments, respectively. Trigonelline also resulted in a lengthening of both S-phase and the cell cycle and a decrease in primary root elongation. Hence, replicon inactivation was responsible for the protracted S-phase. Trigonelline treatment also resulted in a 1.6-fold increase in fork rate (13.8 microm h(-1)) compared with the control (8.4 m h(-1)). The faster fork rate in the larger replicons is in accord with the highly significant positive relationship already established between fork rate and replicon size for various unrelated higher plants.

Alkaloids↗