Improving seed germination and seedling growth of Omphalea oleifera (Euphorbiaceae) for restoration projects in tropical rain forests
ABSTRACT To improve the restoration of tropical rain forests, we tested the germination of seeds of Omphalea oleifera collected from soil (S) and from trees (T) in the 2001 dry season (Spring), at the beginning of a dry season (2005a, winter) and in the rainy season (2005b, winter). All seeds had high water content (WC, 31–33%), and the lipid content varied from 14 to 46%. Seedlings from seeds collected in 2001 were subjected to moderate water stress as a preconditioning treatment for severe stress. T-seeds collected in the dry season had high WC, rapid and high germination percentage; S and T-seeds collected in winter (2005) had also high WC but were dormant. GA3 (250 ppm) broke this dormancy. S-seeds collected in the dry season or at the beginning of it had relatively low WC and low and delayed germination. Some 2001 S-seeds produced albino seedlings. The critical water content for maintaining ecological longevity in these seeds was ∼15%. Seeds collected in 2005b that were dehydrated for 20 days in a moist and fresh atmosphere lost their viability, showing recalcitrant behavior. T-seeds with the lowest lipid content (2005a) after dehydration maintained low germination (15 ± 18%). In all samples the seed size varied widely and was not predictive of seed WC. Embryos taken from dehydrated seeds had two to four times higher WC than the seeds, but germination did not take place. Laboratory and field germination of dormant seeds showed that viability may be maintained for at least 2–3 months on a moist substrate (soil or agar). Moderate water stress at the seedling stage reduced the efficiency of biomass production. Response to this water stress was expressed more in physiological traits than in morphological characters, consequently biomass allocation was maintained and plants retained most of their morphological characteristics (root:shoot ratio, leaf area ratio, specific leaf area, leaf weight ratio). Moderate water stress did not increase the tolerance of seedlings to severe stress, causing leaf shedding and plant death. For restoration purposes we recommend that T-seeds be germinated immediately avoiding dehydration. The use of S-seeds could result in unhealthy seedlings. Seed recalcitrance and the response to moderate water stress restrict germination and establishment to small gaps, where this species naturally grows. We suggest that before introducing O. oleifera in restoration programs, a plant cover should be built to reduce soil water deficit. It is necessary to improve methods to increase potential seed longevity in storage.
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ABSTRACT: Glioblastoma is the most malignant primary brain tumor. Due to its highly promigratory and proinvasive properties, standard therapy including surgery, chemotherapy and radiation fails in eradicating this highly aggressive type of cancer. Here, we evaluated the role of TFPI-2, a Kunitz-type serine protease inhibitor, which has been previously described as a tumor suppressor gene in several types of cancer, including glioma. TFPI-2 expression was absent in five of nine investigated high-grade glioma cell lines. Lentiviral knockdown of TFPI-2 in two of the TFPI-2-expressing cell lines (MZ-18 and Hs 638) was associated with pronounced changes in the cellular behavior: glioma cell proliferation, migration and invasion were significantly increased in TFPI-2 knockdown cells in comparison to empty vector-transfected control cells. Since TFPI-2 might exert its tumor suppressor function by inhibiting MMPs, we subsequently analyzed the effects of specific MMP inhibitors on cell invasion of TFPI-2 KD cells vs. control cells. The data obtained from these experiments suggest that the anti-invasive properties of TFPI-2 are associated with inhibition of MMP-1 and MMP-2, while inhibition of MMP-9 seems to play a minor role in this context. Our findings underscore the important role of TFPI-2 as a tumor suppressor gene and indicate that TFPI-2 may be a useful diagnostic marker for the aggressive phenotype of glial tumors.Neuroscience Letters 06/2011; 497(1):49-54. · 2.03 Impact Factor
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ABSTRACT: To facilitate restoration of the lava field forests surrounding Mexico City, we developed methods to improve the germination and field seedling performance of Quercus rugosa using hydropriming (regulated hydration of seeds in water), and we used special watering regimes to improve seedling acclimation. The size, dry mass, fresh mass and water content of seeds were measured, and curves were generated to evaluate acorn hydration and dehydration. The effects of stratification (5°C), heat shock (50°C) and scarification on germination were tested. All treated seeds and controls were germinated in control chambers at 21°C. One hydropriming cycle (PC) consisted of two hydration days followed by two dehydration days; treatments of 1, 2 and 3 PCs were tested. Seedlings from 1PC to 2PC were acclimated in a shade house under high and low watering regimes (400 and 200 mL week−1, respectively). In the shade house and field, the effects of hydropriming and watering treatments were evaluated by measuring length, basal diameter, crown cover, number of leaves and branches and leaf area of seedlings. Dry and fresh mass were used to calculate acorn water content. Dehydration and hydration curves displayed hysteresis. Acorns exhibited physiological dormancy, which could be overcome by stratification or by 1 month of storage. 1PC led to increased germination rates and final germination. In both the shade house and field, 1PC showed a positive effect on all seedling growth parameters except branch number. Field survival was not affected. Generally, 1PC favoured efficient seed germination, seedling vigour and homogenous plant production.European Journal of Forest Research 01/2012; · 1.96 Impact Factor
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ABSTRACT: The adaptation responses to different water conditions and the drought tolerance of Sophora davidii seedlings were assessed in a greenhouse experiment. Two-month-old seedlings were subjected to the following water supplies for 95days: 100, 80, 60, 40 and 20% of field water capacity. The seedlings at 100% FC had the greatest productivity, height, basal diameter, branch number, leaf number and leaf area. Water supply <80% FC was the threshold of drought-initiated negative effects on seedling growth, yield and physiological processes; these parameters were severely reduced at 20% FC, however, there was no plant death during the experiment. Moreover, water stress decreased leaf relative water content, specific leaf area, leaf area ratio, and water-use efficiency (WUE), whereas it increased the biomass allocation to roots, which resulted in a higher root:stem mass ratio under drought. The S. davidii seedlings tolerated drought by maintaining high leaf relative water content and by reducing branching and leaf expansion. However, low productivity and WUE at 20% FC suggested that seedlings did not produce high biomass under severe drought. Therefore, prior to introducing S. davidii in forestation efforts, a water supply >40% FC is recommended for seedlings to maintain growth and productivity. These results provide insights into limitations and opportunities for establishment of S. davidii in arid regions.Agroforestry Systems 01/2009; 77(3):193-201. · 1.37 Impact Factor