[Responses of plant C:N:P stoichiometry to soil properties on unstable slopes of dry-hot valley]. / 干热河谷失稳性坡面植物碳氮磷化学计量特征对土壤性质的响应.

In this study, we examined plant C:N:P stoichiometry of herbaceous plants in different sections (stable area, unstable area and deposition area) of the unstable slope on both shade and sunny aspects of dry-hot valley with different soil properties. The results showed that C concentration (320.59 g·kg-1), N concentration (12.15 g·kg-1), and N:P ratio (25.37) of shoot on the unstable slope were significantly higher than those of root, with 254.01 g·kg-1, 6.12 g·kg-1 and 13.43, respectively. The average value of the C:N ratio was significantly higher in root (43.09) than shoot (31.90). The C content and N:P ratio of shoot and root in stable and unstable areas were significantly higher than in deposition area, whereas the N content in unstable area was significantly higher than that in deposition area on the sunny slope. In addition, the N and P contents of shoot and the root P content in deposition area were significantly higher than in stable and unstable areas, whereas the C content of root in stable and unstable areas were significantly higher than in deposition area on the shade slope. Moreover, the shoot growth of plants was mainly limited by P, whereas root growth was mainly limited by N and the limitation gradually increased as the section goes down. Soil water content (SWC) was an important factor controlling the C, N, and P contents change of shoot with the relative influence ratios of 28.8%, 20.8%, and 19.9%, respectively. Soil organic carbon (SOC) had a significant impact on the C and P contents of root with the relative influence ratios of 49.5% and 22.1%. The change of root N content was mainly affected by soil pH (24.3%). Our results revealed that nutrient allocation of plant was significantly affected by slope aspects, sections and soil factors, which were mainly constituted by SWC, SOC, and soil pH.

[Carbon source metabolic diversity of soil microbial community under different climate types in the area affected by Wenchuan earthquake].

The MS8.0 Wenchuan earthquake in 2008 led to huge damage to land covers in northwest Sichuan, one of the critical fragile eco-regions in China which can be divided into Semi-arid dry hot climate zone (SDHC) and Subtropical humid monsoon climate zone (SHMC). Using the method of Bilog-ECO-microplate technique, this paper aimed to determine the functional diversity of soil microbial community in the earthquake-affected areas which can be divided into undamaged area (U), recover area (R) and damaged area without recovery (D) under different climate types, in order to provide scientific basis for ecological recovery. The results indicated that the average-well-color-development (AWCD) in undamaged area and recovery area showed SDHC > SHMC, which was contrary to the AWCD in the damaged area without recovery. The AWCD of damaged area without recovery was the lowest in both climate zones. The number of carbon source utilization types of soil microbial in SHMC zone was significantly higher than that in SDHC zone. The carbon source utilization types in both climate zones presented a trend of recover area > undamaged area > damaged area without recovery. The carbon source metabolic diversity characteristic of soil microbial community was significantly different in different climate zones. The diversity index and evenness index both showed a ranking of undamaged area > recover area > damaged area without recovery. In addition, the recovery area had the highest richness index. The soil microbial carbon sources metabolism characteristic was affected by soil nutrient, aboveground vegetation biomass and vegetation coverage to some extent. In conclusion, earthquake and its secondary disasters influenced the carbon source metabolic diversity characteristic of soil microbial community mainly through the change of aboveground vegetation and soil environmental factors.

[Nitrogen leaching and associated environmental health effect in sloping cropland of purple soil].

In this paper, we monitored different forms of nitrogen (N) transported by the subsurface flow under three different natural rainfall events and different fertilizations and conducted an associated risk evaluation on environmental health, which provides scientific basis for controlling N non-point pollution and establishing a reasonable fertilization system in purple soil area. The results showed that there were different forms of N transport by subsurface flow under different rainfall events, where in dissolved nitrogen (DN) accounted for about 53.74% - 99.21%, and nitrate (NO3(-) -N) accounted for about 35.70% - 93.65% of DN, and especially under the moderate rainfall, NO3(-) -N could reach 84.09% - 93.65% of DN. The different N fluxes were the highest under moderate rainfall among different rainfall events, in which the flux of total nitrogen (TN), DN, particle nitrogen (PN), ammonia (NH4(+) -N) and nitrite (NO2(-) -N) reached 737.17, 711.12, 26.06, 12.70 and 0.46 mg x m(-2), respectively, and the NO3(-)-N flux was as high as 686.12 mg x m(-2), showing a huge potential threat on groundwater health. Through the risk assessment on N pollution for groundwater quality, we concluded that the straw returning could be used to effectively alleviate the N leaching and groundwater N pollution; especially, the combined application of organic and chemical fertilizer could effectively mitigate the groundwater pollution, improve soil fertility and increase crop yield.

Expression and production of bioactive human interleukin-18 in transgenic tobacco plants.

The cDNA of human interleukin-18 (hIL-18) was successfully inserted into the genome of tobacco plant, Nicotiana tabacum cv. NC-89, using Agrobacterium tumefaciens-mediated transformation. Insertion and translation of hIL-18 in transformants were confirmed by PCR, ELISA, and Western blot, respectively. The transformed extracts contained the recombinant hIL-18 protein up to 0.05% of total soluble protein. Activity of the recombinant hIL-18 in plant cells was confirmed by the induction of IFN-gamma on IL-18-responsive J6-1 cells by the extracts obtained from the transformants. The expression level of hIL-18 (351 ng g(-1) tobacco tissue) obtained in the present study may be sufficient to induce responses/effects in vivo.