Search results for "botany"
showing 10 items of 4586 documents
Biological activity of resveratrol, a stilbenic compound from grapevines, against Botrytis cinerea, the causal agent for gray mold
1997
The biological activity of resveratrol, a stilbenic compound synthesized by grapevines in response to various stresses, was reevaluated against Botrytis cinerea using a novel in vitro system that enabled direct observation of the fungus with an inverted microscope. We determined that 90 μg resveratrol/ml reduced germination of B. cinerea conidia by ca. 50%. Moreover, resveratrol was shown to significantly reduce mycelial growth of B. cinerea at concentrations ranging from 60 to 140 μg/ml. Exposure to resveratrol at concentrations ranging from 60 to 140 μg/ml resulted in cytological changes in B. cinerea, such as production of secondary or tertiary germ tubes by conidia, cytoplasmic granulat…
Degradation of stilbene-type phytoalexins in relation to the pathogenicity of Botrytis cinerea to grapevines
1996
The ability of eight isolates of Botrytis cinerea to degrade the stilbene phytoalexins, resveratrol and pterostilbene, was compared with their pathogenicity to grapevines. All strains which degraded resveratrol and pterostilbene were highly or moderately pathogenic to in vitro cultures of grapevines (Vitis rupestris) after inoculation with agar disks containing mycelium, while those which were unable to degrade phytoalexins were non-pathogenic. In all cases, the hydroxystilbene-degrading activity was related to the presence of laccase activity in the culture filtrates, as shown by using syringaldazine as substrate. The role of laccase-mediated degradation of phytoalexins in relation to path…
Stilbene Content of MatureVitis viniferaBerries in Response to UV-C Elicitation
2001
A method using HPLC analysis has been used to compare the level of resveratrol and its derivatives, piceid, pterostilbene and epsilon-viniferin, in grapevine berries of three Vitis vinifera varieties. The concentration of these compounds has been evaluated in healthy and Botrytis cinerea infected grape clusters, both in natural vineyard conditions and in response to UV elicitation.
Electrochemical monitoring of ROS influence on seedlings and germination response to salinity stress of three species of the tribe Inuleae.
2019
Solid-state electrochemical methods have been applied to the establishment of patterns of plant growth and response to saline stress using seedlings of Inula helenium L., Dittrichia viscosa (L.) Greuter (Inula viscosa (L.) Aiton), Limbarda crithmoides (L.) Dumort (Inula crithmoides L.). Upon in situ electrochemical generation of reactive oxygen species (ROS) the reactivity with such species was monitored using voltammetric signals associated to the oxidation of polyphenolic components of the plants. A simple kinetic model based on second-order reaction between ROS and polyphenolic components is applied to electrochemical data yielding apparent rate constants which can be correlated with the…
Defoliation and the availability of currently assimilated carbon in the Phleum pratense rhizosphere
2002
Abstract It has been hypothesised that defoliation and aboveground herbivory increase the availability of currently assimilated C to organisms living in plant rhizospheres. We established a growth chamber experiment consisting of Phleum pratense individuals growing in sand culture to examine the short- and long-term effects of defoliation on the availability of current C assimilates in the P. pratense rhizosphere. Using 14CO2 pulse labelling, we followed partitioning of currently assimilated C between shoots, roots and rhizosphere-derived organic matter (RDOM). The experiment constituted of two treatments, defoliation history and recent defoliation, in a fully factorial design. Defoliation …
Micropropagation of Metrosideros excelsa
2008
Multiple shoots were induced on stem segments of a 8-year-old plant of Metrosideros excelsa Sol ex Gaertn. ‘Parnel’. Axillary shoots produced on uncontaminated explants were excised, segmented and recultured in the same medium to increase the stock of shoot cultures. The Murashige and Skoog (MS) medium, augmented with different concentrations of 2- isopenthenyladenine (2iP) and indole-3-acetic acid (IAA), either singly or in combinations, as potential medium for shoot multiplication by nodal segments was tested. In the following experiment equal molar concentrations of four cytokinins [2iP, kinetin, zeatin and N6-benzyladenine (BA)] in combination with equal molar concentrations of three au…
Leaching of n and c from birch leaf litter and raw humus with special emphasis on the influence of soil fauna
1988
Abstract To examine the role of a community of soil animals in N-mineralization and C fluxes in dead organic matter, we established a microcosm system with substrates composed of: (a) birch leaf litter; (b) raw coniferous humus; and (c) litter on humus. Every 3–4 wks the substrates were irrigated with distilled water, and the amounts of NO5-N, NH4-N, total-N and total-C (as well as humic substances at one recording) in the leachates were analyzed. At the end of the experiment, water-soluble and exchangeable forms of N were measured in the test materials. The differences in the release of N were clear both between the replicates with and without soil animals and between the different forms o…
The production of resveratrol (3,5,4'‐trihydroxystilbene) by grapevinein vitrocultures, and its application to screening for grey mould resistance
1992
The ability of grapevine in vitro cultures to synthesise the phytoalexin precursor resveratrol in response to ultraviolet light irradiations is investigated in order to develop methods for screening for resistance to grey mould (Botrytis cinerea Pers.) in grapevines produced as a result of somatic embryogenesis. It is demonstrated that resveratrol formation can be reproducibly induced in leaves of in vitro plantlets. Differences in the production of resveratrol among the three varieties of Vitis vinifera tested (Pinot Noir, Chardonnay and Cabernet Sauvignon) were consistent with observations regarding their field susceptibility to grey mould. The use of phytoalexin induction and of in vitro…
Adventitious shoot regeneration from hypocotyl cultures of service tree(Sorbus domesticaL.)
1992
Effects of growth regulators and N03:NH4 ratio were investigated to determine the mor- phogenic capacity of hypocotyl explants of service tree (Sorbus domestica L.) Organogenic responses were preceded by an initial callus phase and depended mainly on the auxin type used. NAA induced root differentiation whereas IAA added to media containing BA promoted adventitious shoot regeneration. Best results were obtained with 2.5 μM each of BA and IAA (19% of caulogenic explants). This reponse was increased (up to 44%) by varying nitrate to ammonium ratio from 2:1 to 4:1.
Micropropagation of juvenile and adult Sorbus domestica L.
1991
Successful propagation of seedlings and mature trees of Sorbus domestica L. has been achieved by in vitro methods. Multiple shoot formation was obtained by placing shoot apices or nodal segments on a modified Schenck and Hildebrandt medium containing benzyladenine. Regenerated shoots were excised and induced to root on media with auxin. In the best treatments 75–85% of shoots from juvenile material rooted. Rooting capacity of shoots from mature explants was lower (30%) and was not improved by dipping the base of shoots in concentration solutions of indolebutyric or naphthaleneacetic acids. Plantlets were ultimately established in soil.