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1.
Seeds of ten species of Cistaceae, Ericaceae and Poaceae were examinated to compare their responses to high temperatures and ash, simulating the direct effect of fire on germination. A variable response to these factors between families and within species from the same family was detected.In Cistaceae, heat treatment pre-sowing stimulated germination. In Ericaceae, germination was stimulated by thermic shock, but a wide range of response was detected (between all four species), from Erica ciliari, very sensitive, to Daboecia cantabrica and Calluna vulgaris which showed no significant response. The range of reaction shown by the species of this family suggest that the size of the seeds is directly related to the difference in response, at least in species with a similar structure. In Poaceae, germination was not found to be dependent upon thermic shock.The effect of ash varies in magnitude. Although it decreased the germination percentage in all species, in Avenula marginata (Poaceae) the effect was not statistically significant, whilst in Ericaceae, particularly in those showing the highest levels of germination in the control (C. vulgaris and E. umbellata), the effect is to inhibit germination completely. In respect to the effect of ash the families could be arranged in the order Ericaceae>Cistaceae>Poaceae.Complex interactions between various dormancy types and seed size could explain these results. In species which depend on physical dormancy temperature has an important role. When other dormancy type is dominant in the control of germination, the medium characteristics could have a relevant role on seed response. In addition, the seed-size could determine the threshold of tolerance to temperature. 相似文献
3.
4.
Hideyuki Matsuura Kumiko Ohashi Hiroshi Sasako Noriko Tagawa Yuuko Takano Yumiko Ioka Kensuke Nabeta Teruhiko Yoshihara 《Plant Growth Regulation》2008,54(1):31-36
Root exudate of Vigna unguiculata was extracted from a soil system consisting of charcoal and vermiculite. Germination stimulating activity for Striga gesnerioides was found in extracts of the soil system, and an active compound was isolated. The chemical structure of the active ingredient
was determined to be (+)-4-O-acetylorobanchol, based on analysis of the spectral data of 1-D and 2-D NMR together with nuclear Overhauser effect (NOE)
experiments. Application of the active compound to the seeds of S. gesnerioides at a concentration of 0.35 × 10−9 mol/disk led to 69% germination. The germination observed with application of GR-24, a positive control, at 0.57 × 10−10 mol/disk was 80%. 相似文献
5.
J. P. DUBEY 《The Journal of eukaryotic microbiology》1997,44(6):592-602
ABSTRACT. The development of Toxoplasma gondii was studied in mice fed bradyzoites. At one hour after oral inoculation (HAI), bradyzoites were found in cells of the surface epithelium and the lamina propria of the small intestine, primarily the ileum. Division into two tachyzoites was first observed at 18 HA1 in the intestine. At 24 HAI, organisms were also seen in mesenteric lymph nodes. Organisms were first detected in the brain at six days after oral inoculation with bradyzoites (DAI) but not consistently until 10 DAI. Immunohistochemical staining with bradyzoite specific (BAG-5 antigen) anti-serum showed that bradyzoites retained their BAG-5 reactivity even after the first division into two tachyzoites in the intestine at 18 HAL BAG-5 positive organisms were not seen 2–5 DAI. BAG-5 antigens reappeared in T. gondii at 6 DAI. Whole mice and individual tissues of mice fed bradyzoites were bioassayed in cats and mice for the presence of bradyzoites. Feces of cats fed murine tissues were examined for oocyst shedding for short prepatent periods. Bradyzoites were present in the intestines of mice up to 12 HA1 but not at 18 HAI, and tachyzoites and not bradyzoites disseminated to other tissues from the intestine. Bradyzoites were again detected 6 DAI. Using the mouse bioassay, T. gondii was first detected in peripheral blood at 24 HA1 and more consistently at 48 HAL Using a pepsin-digestion procedure and mouse bioassay, organisms were demonstrated in many tissues of mice 15 and 49 DAI. 相似文献
6.
《Fungal biology》2020,124(12):1058-1067
Fungal growth often appears in a surrounding where water and nutrients are scarce. The impact of this environment during sporogenesis on subsequent growth is often neglected.This study investigates the effect of water availability during sporogenesis on subsequent early growth. Therefore, a carbon-depleted substrate was constructed. Humidity is then the only parameter of interest. The water conditions during sporogenesis, and during subsequent growth, were varied. This is a stressing environment: no carbon source is present, and water provided solely via the vapour.The lag time, , and initial growth rate, , of the germ tubes were monitored.The effect of history on germination and initial growth depends on the of the environment. Only at low do spores produced at low have a smaller and higher compared to those grown at high . This result was remarkably pronounced when the substrate was also made hydrophobic: growth only occurred when spores were developed at low and placed in high .Spores grown on lowered attract more water. It is hypothesized that this attraction affects subsequent growth behaviour, and is the reason why growth on hydrophobic glass only prevails in the condition of high and lowered history.We demonstrate the influence of cultivation conditions on germination, which becomes more pronounced in a more desiccated environment. 相似文献
7.
J. Yamaguchi S. Itoh T. Saitoh A. Ikeda T. Tashiro Y. Nagato 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1999,98(1):32-38
β-Amylase deficiency in various cultivars of rice was examined at the molecular level. Using an antibody against β-amylase
purified from germinating seeds of rice, we were able to demonstrate the expression and organization of the β-amylase gene
in normal and deficient cultivars. Although β-amylase is a starch-hydrolyzing enzyme, as is α-amylase, the β-amylase protein/gene
is expressed differently from the α-amylase protein/gene; i.e. (1) β-amylase is synthesized only in aleurone cells, (2) the
enzyme production in the embryo-less half-seeds is not under hormonal control. We identified some cultivars of rice that are
deficient for β-amylase activity. We present new evidence that synthesis is blocked at the level of mRNA synthesis in the
deficient cultivars. The usefulness of β-amylase as a crop trait is also discussed.
Received: 8 May 1998 / Accepted: 5 June 1998 相似文献
8.
E. B. Kirichenko Yu. V. Orlova D. V. Kurilov 《Russian Journal of Plant Physiology》2008,55(6):846-853
Abstrac The composition of essential oil of Artemisia lerchiana Web. plants growing in Volgograd oblast was studied. Sampling was performed from plots contrasting in climatic and soil characteristics.
Essential oil was obtained by hydrodistillation. The content of essential oil in shoot biomass increased gradually during
shoot formation, flower bud formation, and flowering beginning and then decreased. The highest content of essential oil varied
from 1.1 to 1.5% of plant dry weight at the stage of flower bud formation. More than thirty compounds were identified by gas
chromatography-mass spectrometry. The following major components were found: camphor, borneol, bornylacetate, camphene, and
1,8-cineole. Some of compounds (sesquiterpenes and sesquiterpenoids) were identified for the first time. The time-course of
accumulation of essential oil components strongly depended on habitat edaphic factors and climatic conditions during the year
of sampling. The results permit a conclusion that A. lerchiana is a valuable producer of essential oils.
Original Russian Text ? E.B. Kirichenko, Yu.V. Orlova, D.V. Kurilov, 2008, published in Fiziologiya Rastenii, 2008, Vol. 55,
No. 6, pp. 934–941. 相似文献
9.
《Saudi Journal of Biological Sciences》2021,28(11):6500-6507
The nanoparticle has been reported to have severe effects and metabolic disorders in crops. Analysis of poisoning exposure to titanium dioxide is very important during the seed germination stage. Measuring the levels of water supply, reserve mobilization and redox metabolism with germination success is a prerequisite for understanding the TiO2 stress mechanism. These measurements are carried out using different methods, including germination tests, determination of growth parameters, analysis of reserve mobilization processes and redox activities under different stress conditions. The significant effects (P < 0.05) of TiO2 on seed germination were determined by analysis of variance (2 ways-ANOVA). We considered the effect of TiO2 dose (0 and 50 mg/L) and time of exposure (1,2,3,4 and 5 days). The results showed that TiO2 treatment significantly affected the germination rate (GR), the mean daily germination (MDG), the tissues dry weights, water supply, solute leakage, and induced oxidative stress and antioxidant enzyme activities. Oxidative and metabolic disturbances are among the major causes of the successful germination of pea seeds. 相似文献
10.
Guenter Harth Alea A. Mills Thais Souto-Padrón Wanderley de Souza 《Molecular and cellular biochemistry》1992,109(1):25-36
Two monoclonal antibodies were used to biochemically characterize glycoprotein 72 (GP72) from Trypanosoma cruzi and to localize the protein in live and fixed parasites by indirect immunofluorescence and in thin section of parasites by immunogold electron microscopy. GP72 was shown in immunoblots to be specific for the epimastigote stage; the protein could not be detected in trypomastigotes. Each antibody reacted with a different epitope on the glycoprotein and deglycosylation of GP72 ablated reactivity with one of the antibodies. Indirect immunofluorescence and electron microscopic evaluation of parasite associated gold particles showed the presence of GP72 in the cell surface membrane including the flagellar pocket and the cytostome. In addition, cytoplasmic membrane vesicles of the endosomal-lysosomal system stained intensely. 相似文献