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Relations Between Indoleacetic Acid, Calcium Ions and Ethylene in the Regulation of Growth and Cell Wall Composition in Picea abies 总被引:2,自引:0,他引:2
Effects of indoleacetic acid, calcium ions and ethylene on thegrowth of and deposition of different cell wall fractions inthe hypocotyl of Norway spruce (Picea abies (L.) Karst.) seedlingswere investigated. Indoleacetic acid progressively stimulated cellulose depositionas the amount of added Ca2+ increased. In contrast, indoleaceticacid promoted lignification and the deposition of non-cellulosicpolysaccharides only in the absence of added Ca2+ . When Ca2+was added, the indoleacetic acid effect disappeared. Similarly,indoleacetic acid promoted non-cellulosic polysaccharide depositiononly in the absence of ethylene. At increasing ethylene levelsthe effect of indoleacetic acid on non-cellulosic polysaccharidedeposition disappeared and indoleacetic acid instead promotedcellulose deposition. The response to indoleacetic acid depended on the Ca2+ concentrationand on the rate of ethylene production. The relationship betweenindoleacetic acid and Ca2+ seemed complex, but clearly indoleaceticacid could partially overcome a Ca2+ deficiency. The resultssuggest that ethylene may be a factor of particular importancefor the type of polysaccharide deposition during cell wall formation. Key words: Calcium, cell wall, conifers, ethylene, indoleacetic acid 相似文献
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FLORIS M. VAN BEEST LEIF EGIL LOE ATLE MYSTERUD JOS M. MILNER 《The Journal of wildlife management》2010,74(2):219-227
ABSTRACT The practice of feeding cervids in winter, either as a supplement to enhance nutritional status or to divert animals away from roads, railways, or vulnerable habitats, is rising noticeably. Moose (Alces alces) densities in Scandinavia are currently at historically high levels, resulting in amplified damage to economically important young Scots pine (Pinus sylvestris) forest stands. Nevertheless, there is limited information as to how diversionary feeding affects herbivore space use and habitat selection. We followed 32 female moose marked with Global Positioning System collars to evaluate 1) if feeding stations serve as attraction points to the extent that habitat-selection patterns resemble those of central-place foragers (i.e., high usage and more uniform selection close to the attraction point), and 2) if moose using feeding sites select young pine stands less than those not using feeding sites. Moose that used diversionary forage concentrated their space use around feeding stations and selected habitats as predicted for a central-place forager with a decreasing probability of using areas away from feeding sites and a low degree of habitat selectivity close to feeding sites. However, moose that used feeding sites continued to select young pine stands to the same extent as moose that did not use feeding sites. Feeding sites were, therefore, not successful in diverting moose away from valuable natural browse, so we recommend wildlife managers establish feeding sites in sacrifice areas where moose browsing is permissible and, if possible, >1 km from young pine plantations. 相似文献
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ABSTRACT. Cells of the ciliate Tetrahymena thermophila failed to establish cultures in lipid-free standard synthetic nutrient medium if the initial population density was 250 cells per ml or less. These cells died within 10 h, but were saved and formed dense cultures if their medium was supplemented with 10 μg per ml of either certain phospholipids, 1,2-di-, 1-monoglycerides, fatty acids, long-chain alcohols, or sterols. Cell multiplication was followed in cultures in which the standard synthetic medium was supplemented with a selection of the compounds listed above. It was observed that the cells in the supplemented cultures in their exponential phases of growth had about the same average doubling times as control cells starting multiplication at 10-fold higher initial cell densities in lipid-free medium. These cells have been grown for decades in lipid-free synthetic nutrient media at short (ca. two-three h) doubling times. Therefore lipids have been considered nutritionally non-essential for growth and multiplication of these cells. We propose that those compounds that rescue the cells at low cell densities act as "proliferation signals," sensu lato . This effect of lipids and long-chain alcohols has so far remained unnoticed. 相似文献
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KOLBY JARDINE FREDERIK WEGENER LEIF ABRELL JOOST VAN HAREN CHRISTIANE WERNER 《Plant, cell & environment》2014,37(2):414-424
Acetylation of plant metabolites fundamentally changes their volatility, solubility and activity as semiochemicals. Here we present a new technique termed dynamic 13C‐pulse chasing to track the fate of C1–3 carbon atoms of pyruvate into the biosynthesis and emission of methyl acetate (MA) and CO2. 13C‐labelling of MA and CO2 branch emissions respond within minutes to changes in 13C‐positionally labelled pyruvate solutions fed through the transpiration stream. Strong 13C‐labelling of MA emissions occurred only under pyruvate‐2‐13C and pyruvate‐2,3‐13C feeding, but not pyruvate‐1‐13C feeding. In contrast, strong 13CO2 emissions were only observed under pyruvate‐1‐13C feeding. These results demonstrate that MA (and other volatile and non‐volatile metabolites) derive from the C2,3 atoms of pyruvate while the C1 atom undergoes decarboxylation. The latter is a non‐mitochondrial source of CO2 in the light generally not considered in studies of CO2 sources and sinks. Within a tropical rainforest mesocosm, we also observed atmospheric concentrations of MA up to 0.6 ppbv that tracked light and temperature conditions. Moreover, signals partially attributed to MA were observed in ambient air within and above a tropical rainforest in the Amazon. Our study highlights the potential importance of acetyl coenzyme A (CoA) biosynthesis as a source of acetate esters and CO2 to the atmosphere. 相似文献