Ecological restoration design of a stream on a college campus in central Ohio

Straightened stream channels and altered and drained wetlands have adversely impacted streams and rivers throughout Midwestern USA, where some of the most dense drainage and riparian ecosystem alteration in the world have occurred. A segment of Grave Creek on The Ohio State University's Marion (OSU Marion) campus in Ohio, USA, with its lack of riparian ecosystems, illustrates the transformation of a natural fluvial ecosystem to an unstable and “simplified” aquatic environment that requires continued maintenance and provides little value to the surrounding landscape or to the university. However, the straight ditch, available adjacent riparian land and existing hydric soil give OSU Marion a great opportunity to demonstrate a project of stream and wetland restoration on a college campus. To restore the natural ecological stability of OSU Marion's “back yard” and to provide habitat improvement to Grave Creek and its surrounding landscape on the OSU Marion campus, we have designed a restoration of 1.1 km of Grave Creek meandering to the east of the existing sewer, using the two-stage channel techniques, and about 0.6–0.8 ha of adjacent wetland. We estimate that restoration on this scale will cost about US$ 200,000–300,000, not including monitoring of the results. To fulfill this project, it is likely that an opportunity for using this restoration in a stream/wetland loss mitigation will present itself in this region of Ohio while a long-term pre- and post-construction monitoring plan and more detailed design would be expected as the next step.     

墨兰菌根的结构及酸性磷酸酶定位研究

利用光学显微镜、电子显微镜及细胞化学方法,对墨兰菌根的结构和酸性磷酸酶定位进行了初步研究。结果表明墨兰具有典型的兰科植物根结构,发现该兰花的根的外皮层不具薄壁通道细胞,菌根真菌通过破坏部分根被和外皮层细胞而侵入根的皮层细胞并在细胞内形成菌丝结,侵入的菌丝被染菌皮层细胞质膜和电子透明物质包围,进一步被消化并聚集成衰败菌丝团块。酸性磷酸酶在染菌皮层细胞及包围菌丝的皮层细胞质膜和衰败菌丝细胞壁上有强烈的酶反应,衰败菌丝周围分布有许多单层膜的含酶小泡,它们可相互愈合形成大的含酶泡或与包围菌丝的质膜融合,类似于兰科植物共生原球茎中观察到的现象。说明皮层细胞可主动释放水解酶参与对菌丝的消化     

Ultraviolet-B irradiation-induced freezing tolerance in relation to antioxidant system in winter wheat (Triticum aestivum L.) leaves

Seven-day-old seedlings of winter wheat (Triticum aestivum L.) in a growth chamber were exposed to ultraviolet-B (UV-B) irradiation for 20 days with daily biologically effective (BE) UV-B irradiation (UV-B_BE) at low (4.2 kJ m⁻² day⁻¹, L_UVB) and high (7.0 kJ m⁻² day⁻¹, H_UVB) levels. The UV-B irradiated seedlings and the control without UV-B irradiation were then subjected to freezing stress at −6 °C for 6 h and recovered to 20 °C with gradually increased temperature, to investigate the effects of UV-B irradiation on freezing tolerance. During the UV-B exposure, both L_UVB and H_UVB irradiated seedlings had lower half lethal temperature (LT₅₀) values in comparison with the control, and L_UVB more effectively decreased the LT₅₀ values than H_UVB. Moreover, foliar concentrations of thiobarbituric acid reactive substances (TBARS) in the UV-B irradiated seedlings were lower than that of control after recovery from freezing stress. Hydrogen peroxide (H₂O₂) rapidly increased after UV-B exposure, as did activity of superoxide dismutase (SOD). After recovery from freezing stress, activities of catalase (CAT), guaiacol peroxidase (GPX) and glutathione reductase (GR) increased in both L_UVB and H_UVB leaves, whereas activities of ascorbate peroxidase (APX) and monodehydroascorbate reductase (MDHAR) significantly increased only in the L_UVB leaves. Furthermore, the ascorbic acid (AsA) concentration and reduced-to-oxidized ascorbate ratio (AsA/DHA) increased in the L_UVB leaves both at the end of UV-B exposure and after recovery from freezing stress. However, the reduced glutathione (GSH) concentration, together with reduced-to-oxidized glutathione ratio (GSH/GSSG) increased in both L_UVB and H_UVB leaves after recovery from freezing stress. UV-B irradiation increased freezing tolerance in winter wheat seedlings, and this response appears to involve the scavenging enzymes and compounds in the antioxidant defense systems, particularly the ascorbate–glutathione cycle.     

Production of xylanase from a newly isolated <Emphasis Type="Italic">Penicillium</Emphasis> sp. ZH-30

A new strain of Penicillium sp. ZH-30 that produces xylanase was isolated from soil. According to the morphology and comparison of internal transcribed spacer (ITS) rDNA gene sequence, the strain Penicillium sp. ZH-30 was identified as a strain of Penicillium oxalicum. When xylan or wheat bran was used as substrate at 30°C for 3 days under submerged cultivation, xylanase production was 5.3 and 13.3 U ml⁻¹, respectively. The temperature and pH for optimum activity were 50°C and 5.0–6.0, respectively.     

Transformation and mineralization of soil organic nitrogen by the humivorous larva of Pachnoda ephippiata (Coleoptera: Scarabaeidae)

In common bean (Phaseolus vulgaris L.), Fusarium root rot (caused by Fusarium solani f. sp. phaseoli) disease severity is increased by environmental factors that stress the plant. The current study used reciprocal grafting techniques with the resistant cultivar FR266 and the susceptible cultivar Montcalm to determine if the genetic control of resistance is conferred by the rootstock (root genotype) or the scion (shoot genotype) and if root vigor played a role in resistance. The influence of a compacted layer on root and shoot genotype response and root rot resistance was studied. Root rot resistance was found to be controlled by the root genotype, such that on a scale of 1 to 7 (severe disease) the FR266 root had an average score of 2.3 and the Montcalm root had an average score of 4.4. However, when grafted plants were grown in the presence of a compacted layer, the FR266 root and/or shoot genotype in any graft combination with the susceptible Montcalm had reduced root rot (score = 2.4 average) than the Montcalm self graft (score = 4.5). Root mass was shown to be controlled by the root genotype in the absence of compaction such that the FR266 root was 26% larger that the Montcalm root when grafted onto a FR266 shoot or a Montcalm shoot. When a compacted layer was present the root and shoot genotype both contributed to root mass. Average root diameter was controlled by the shoot genotype, as the FR266 shoot grafted to Montcalm or FR266 roots had thicker roots (average diameter 0.455 mm) than the Montcalm shoot (average diameter 0.418 mm). This study shows evidence that root vigor in the presence of Fusarium disease pressure should be evaluated to effectively develop common bean lines resistant to Fusarium root rot across a range of environments.     

Involvement of nitric oxide in cerebroside-induced defense responses and taxol production in <Emphasis Type="Italic">Taxus yunnanensis</Emphasis> suspension cells

This work was to characterize the generation of nitric oxide (NO) in Taxus yunnanensis cells induced by a fungal-derived cerebroside and the signal role of NO in the elicitation of plant defense responses and taxol production. (2S,2′R,3R,3′E,4E,8E)-1-O-β-d-glucopyranosyl-2-N-(2′-hydroxy-3′-octadecenoyl)-3-hydroxy-9-methyl-4,8-sphingadienine at 10 μg/ml induced a rapid and dose-dependent NO production in the Taxus cell culture, reaching a maximum within 5 h of the treatment. The NO donor sodium nitroprusside (SNP) potentiated cerebroside-induced H₂O₂ production and cell death. Inhibition of nitric oxide synthase activity by phenylene-1,3-bis(ethane-2-isothiourea) dihydrobromide or scavenging NO by 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide partially blocked the cerebroside-induced H₂O₂ production and cell death. Moreover, NO enhanced cerebroside-induced activation of phenylalanine ammonium-lyase and accumulation of taxol in cell cultures. These results are suggestive of a role for NO as a new signal component for activating the cerebroside-induced defense responses and secondary metabolism activities of plant cells. Taxol is a trademark of Bristol-Myers Squibb, Madison, NJ.     

Effects of fertigation scheme on N uptake and N use efficiency in cotton

While fertigation can increase fertilizer use efficiency, there is an uncertainly as to whether the fertilizer should be introduced at the beginning of the irrigation or at the end, or introduced during irrigation. Our objective was to determine the effect of different fertigation schemes on nitrogen (N) uptake and N use efficiency (NUE) in cotton plants. A pot experiment was conducted under greenhouse conditions in year 2004 and 2005. According to the application timing of nitrogen (N) fertilizer solution and water (W) involved in an irrigation cycle, four nitrogen fertigation schemes [nitrogen applied at the beginning of the irrigation cycle (N–W), nitrogen applied at the end of the irrigation cycle (W–N), nitrogen applied in the middle of the irrigation cycle (W–N–W) and nitrogen applied throughout the irrigation cycle (N&W)] were employed in a completely randomized design with four replications. Cotton was grown in plastic containers with a volume of 84 l, which were filled with a clay loam soil and fertilized with 6.4 g of N per pot as unlabeled and ¹⁵N-labeled urea for 2004 and 2005, respectively. Plant total dry matter (DM) and N content in N–W was significantly higher than in N&W in both seasons, but these were not consistent for W–N and W–N–W treatments. In year 2005, a significantly higher nitrogen derived from fertilizer (NDFF) for the whole plant was found in W–N and N–W than that in W–N–W and N&W. Fertigation scheme had a consistent effect on total NUE: N–W had the highest NUE for the whole plant, but this was not significantly different from W–N. Treatments W–N and W–N–W had similar total NUE, and N&W had the lowest total NUE. After harvesting, the total residual fertilizer N in the soil was highest in W–N, lowest in N–W, but this was not significantly different from N&W and W–N–W treatments. Total residual NO₃–N in the soil in N&W and W–N treatments was 20.7 and 21.2% higher than that in N–W, respectively. The total ¹⁵N recovery was not statistically significant between the four fertigation schemes. In this study, the fertigation scheme N–W (nitrogen applied at the beginning of an irrigation cycle) increased DM accumulation, N uptake and NUE of cotton. This study indicates that Nitrogen application at the beginning of an irrigation cycle has an advantage on N uptake and NUE of cotton. Therefore, NUE could be enhanced by optimizing fertilization schemes with drip irrigation.     

Growth promoting effect of a transgenic <Emphasis Type="Italic">Bacillus mucilaginosus</Emphasis> on tobacco planting

In this study, we have investigated the plant growth promoting effect of Bacillus mucilaginosus strain D₄B₁, a rhizosphere soil organism, and its transgenic strain NKTS-3 on tobacco planting. The transgenic strain contains a phytase expression cassette that can express high active phytase extracellularly and hydrolyze phytate in the soil to liberate inorganic phosphorus for the growth of tobacco plants. Greenhouse study and field experiments showed that both wild-type B. mucilaginosus and the transgenic strain could promote tobacco plant growth. Moreover, the transgenic strain promoted tobacco plant growth (235% more than control in pot experiments and 125% more than control in field experiments) was higher than the wild-type B. mucilaginosus (183% more than control in pot experiments and 108% more than control in field experiments). In addition, the inoculation with transgenic rhizobacteria could significantly improve root acquisition of phosphorus and increase the phosphorus content of the plant.