Discovery of Resveratrol and its Derivatives as Novel Antiviral and Anti- Phytopathogenic-Fungus Agents.

BACKGROUND: Plant diseases caused by viruses and pathogens have posed a serious threat to global agricultural production and are difficult to control. Natural products have always been a valuable source for lead discovery in medicinal and agricultural chemistry. The natural product resveratrol was found to have good antiviral activity against the tobacco mosaic virus (TMV) and fungicidal activities against 14 kinds of phytopathogenic fungi. OBJECTIVE: The aim of this work was to design, synthesize a series of derivatives of resveratrol, and evaluate their antiviral and fungicidal activities systematically. METHODS: Novel resveratrol sulfonate derivatives were prepared by a convenient synthesis method from resveratrol, alkyl sulfonyl chloride, aryl sulfonyl chloride, and heterocyclic sulfonyl chloride. Their structures were also identified by nuclear magnetic resonance (NMR) spectroscopy and high-resolution mass spectrometry (HRMS). RESULTS: Most of the targets were obtained at a high yield. Compounds I-2, I-5, I-10, II-2, and II-4, with excellent antiviral activities, showed higher anti-TMV activities than those of lead compounds and commercial ribavirin (inhibitory rates of 38, 37, and 38% at 500 µg/mL for inactivation, curative, and protection activities in vivo, respectively). In particular, compounds I-5, I-10, II-2, and II-4 displayed similar inhibitory effects as ningnanmycin (inhibitory rates of 54, 56, and 58% at 500 µg/mL for inactivation, curative, and protection activities in vivo, respectively), the best antiviral agent at present, thereby emerging as new antiviral pilot compounds. Further fungicidal activity tests showed that resveratrol derivatives also displayed broad-spectrum fungicidal activities. CONCLUSION: The anti-TMV activities of these compounds were discovered for the first time. Some of these simply structured compounds showed higher TMV inhibitory effects than ribavirin. The current study provided valuable insights into the antiviral and fungicidal activities of resveratrol derivatives, but more modification of the structure should be conducted.

Relative contributions of different substrates to soil N2O emission and their responses to N addition in a temperate forest.

With increasing nitrogen (N) deposition, soil nitrous oxide (N2O) emission is expected to increase, causing positive feedback to global warming. However, the substrates of soil N2O emission, especially their responses to N addition, are still unclear. Here, we conducted an in situ 15N tracing experiment to study the substrates of N2O (i.e., ammonium-derived, nitrate-derived and organic N-derived N2O emission) under N addition treatment in a temperate forest in northeast China. Nitrate derived N2O through denitrification contributed most to the total N2O emission, pointing to the importance of denitrification under ambient N deposition. NH4NO3 addition of 50 kg N ha-1 yr-1 significantly increased organic N derived N2O on the 6th day after N addition, which suggests that heterotrophic nitrification may be the dominating process with higher N deposition rate. However, because soil pH and the examined functional genes did not change after N addition, future studies should be carried out to understand if the increase of heterotrophic nitrification is transient. Our study emphasizes the role of organic N pool in soil N2O emissions, highlighting the importance of considering the heterotrophic nitrification process while studying soil N cycling or modeling soil N2O emission.

Phosphorus Reduces Negative Effects of Nitrogen Addition on Soil Microbial Communities and Functions.

Increased soil nitrogen (N) from atmospheric N deposition could change microbial communities and functions. However, the underlying mechanisms and whether soil phosphorus (P) status are responsible for these changes still have not been well explained. Here, we investigated the effects of N and P additions on soil bacterial and fungal communities and predicted their functional compositions in a temperate forest. We found that N addition significantly decreased soil bacterial diversity in the organic (O) horizon, but tended to increase bacterial diversity in the mineral (A) horizon soil. P addition alone did not significantly change soil bacterial diversity but mitigated the negative effect of N addition on bacterial diversity in the O horizon. Neither N addition nor P addition significantly influenced soil fungal diversity. Changes in soil microbial community composition under N and P additions were mainly due to the shifts in soil pH and NO3- contents. N addition can affect bacterial functional potentials, such as ureolysis, N fixation, respiration, decomposition of organic matter processes, and fungal guilds, such as pathogen, saprotroph, and mycorrhizal fungi, by which more C probably was lost in O horizon soil under increased N deposition. However, P addition can alleviate or switch the effects of increased N deposition on the microbial functional potentials in O horizon soil and may even be a benefit for more C sequestration in A horizon soil. Our results highlight the different responses of microorganisms to N and P additions between O and A horizons and provides an important insight for predicting the changes in forest C storage status under increasing N deposition in the future.

Different fates of deposited NH4+ and NO3- in a temperate forest in northeast China: a 15 N tracer study.

Increasing atmospheric reactive nitrogen (N) deposition due to human activities could change N cycling in terrestrial ecosystems. However, the differences between the fates of deposited NH4+ and NO3- are still not fully understood. Here, we investigated the fates of deposited NH4+ and NO3-, respectively, via the application of 15 NH4 NO3 and NH415 NO3 in a temperate forest ecosystem. Results showed that at 410 days after tracer application, most 15NH4+ was immobilized in litter layer (50 ± 2%), while a considerable amount of 15NO3- penetrated into 0-5 cm mineral soil (42 ± 2%), indicating that litter layer and 0-5 cm mineral soil were the major N sinks of NH4+ and NO3-, respectively. Broad-leaved trees assimilated more 15 N under NH415 NO3 treatment compared to under 15 NH4 NO3 treatment, indicating their preference for NO3--N. At 410 days after tracer application, 16 ± 4% added 15 N was found in aboveground biomass under 15NO3- treatment, which was twice more than that under 15NH4+ treatment (6 ± 1%). At the same time, approximately 80% added 15 N was recovered in soil and plants under both treatments, which suggested that this forest had high potential for retention of deposited N. These results provided evidence that there were great differences between the fates of deposited NH4+ and NO3-, which could help us better understand the mechanisms and capability of forest ecosystems as a sink of reactive nitrogen.

Biogeographic Distribution Patterns of Bacteria in Typical Chinese Forest Soils.

Microbes are widely distributed in soils and play a very important role in nutrient cycling and ecosystem services. To understand the biogeographic distribution of forest soil bacteria, we collected 115 soil samples in typical forest ecosystems across eastern China to investigate their bacterial community compositions using Illumina MiSeq high throughput sequencing based on 16S rRNA. We obtained 4,667,656 sequences totally and more than 70% of these sequences were classified into five dominant groups, i.e., Actinobacteria, Acidobacteria, Alphaproteobacteria, Verrucomicrobia, and Planctomycetes (relative abundance >5%). The bacterial diversity showed a parabola shape along latitude and the maximum diversity appeared at latitudes between 33.50°N and 40°N, an area characterized by warm-temperate zones and moderate temperature, neutral soil pH and high substrate availability (soil C and N) from dominant deciduous broad-leaved forests. Pairwise dissimilarity matrix in bacterial community composition showed that bacterial community structure had regional similarity and the latitude of 30°N could be used as the dividing line between southern and northern forest soils. Soil properties and climate conditions (MAT and MAP) greatly accounted for the differences in the soil bacterial structure. Among all soil parameters determined, soil pH predominantly affected the diversity and composition of the bacterial community, and soil pH = 5 probably could be used as a threshold below which soil bacterial diversity might decline and soil bacterial community structure might change significantly. Moreover, soil exchangeable cations, especially Ca(2+) (ECa(2+)) and some other soil variables were also closely related to bacterial community structure. The selected environmental variables (21.11%) explained more of the bacterial community variation than geographic distance (15.88%), indicating that the edaphic properties and environmental factors played a more important role than geographic dispersal limitation in determining the bacterial community structure in Chinese forest soils.

[Effects of nitrification inhibitors DCD and DMPP on cinnamon soil' s gross nitrogen mineralization and nitrification rates].

By using 15N pool dilution technique in combining with in situ soil cultivation, this paper studied the effects of nitrification inhibitors dicyandiamide (DCD) and 3,4-dimethylpyrazole phosphate (DMPP) on the gross nitrogen (N) mineralization and nitrification rates in a saline-alkali cinnamon soil in North China. The experiment was carried out in a maize-wheat rotation field in Yuncheng City of Shanxi Province, and three treatments were installed, i.e., urea, urea + DCD, and urea + DMPP. In the first two weeks after fertilization, DCD and DMPP made the gross N mineralization rate and gross N nitrification rate decreased by 25.5% and 7.3%, and by 60.3% and 59.1%, respectively, with a significant difference in the gross N mineralization rate but less difference in the gross N nitrification rate between the effects of DCD and DMPP. However, significant difference was observed in the gross N nitrification rate between the effects of DCD and DMPP after seven weeks of fertilization. The gross N mineralization and nitrification rates and the NH4+ and NO3-consumption rates after two weeks of fertilization were 7.2-10.0, 5.5-21.5, 9.1-12.2, and 5.1-8.4 times of those before fertilization, respectively, possibly due to the stimulating effect of N fertilization. DCD and DMPP made the fertilizer urea N more maintained in NH(4+)-N form and less accumulated in NO(3-)-N form in soil. The decreases of the gross N mineralization and nitrifications rate in the test soil due to the effects of the inhibitors would benefit the reduction of N2O emission from the soil.