Northeast Institute of Geography and Agroecology, Chinese Academy Of Sciences
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The Indeterminate Domain Protein ROC1 Regulates Chilling Tolerance via Activation of DREB1B/CBF1 in Rice
No full textAbiotic stress, including salinity, drought and cold, severely affect diverse aspects of plant development and production. Rice is an important crop that does not acclimate to cold; therefore, it is relatively sensitive to low temperature stress. Dehydration-responsive element-binding protein 1s (DREB1s)/C-repeat binding factors (CBFs) are well known for their function in cold tolerance, but the transcriptional regulation of CBFs remains elusive, especially in rice. Here, we performed a yeast one-hybrid assay using the promoter of CBF1, a cold-induced gene, to isolate transcriptional regulators of CBF1. Among the seven candidates identified, an indeterminate domain (IDD) protein named ROC1 (a regulator of CBF1) was further analyzed. The ROC1 transcript was induced by exogenously-treated auxin, while it was not altered by cold or ABA stimuli. ROC1-GFP was localized at the nucleus, and ROC1 showed trans-activation activity in yeast. The electrophoretic mobility shift assay (EMSA) and ChIP analyses revealed that ROC1 directly bound to the promoter of CBF1. Furthermore, ROC1 mutants exhibited chilling-sensitive symptoms and inhibited cold-mediated induction of CBF1 and CBF3, indicating that ROC1 is a positive regulator of cold stress responses. Taken together, this study identified the CBF1 regulator, and the results are important for rice plant adaptation to chilling stress
Integrated Use of GCM, RS, and GIS for the Assessment of Hillslope and Gully Erosion in the Mushi River Sub-Catchment, Northeast China
No full textThe black soil region of Northeast China has suffered from severe soil erosion by water. Hillslope and gully erosion are the main erosion types. The objective of this research was to integrate the assessment of hillslope and gully erosion and explore spatial coupling relations between them in the Mushi River sub-catchment using geographical conditions monitoring (GCM) including remote sensing (RS) and geographic information system (GIS) techniques. The revised universal soil loss equation (RUSLE) model and visual satellite image interpretation were used to evaluate hillslope and gully erosion, respectively. The results showed that (1) the study area as a whole had slight erosion due to rill and sheet erosion, but suffered more serious gully erosion, which mainly occurs in cultivated land; (2) GCM contributed to the overall improvement of soil erosion assessment, but the RUSLE model likely overestimates the erosion rate in dry land; (3) the hillslope and gully erosion were stronger on sunny slopes than on shady slopes, and mainly occurred at middle elevations. When the slope was greater than 15 degrees, the slope was not the main factor restricting the erosion, while at steeper slopes, the dominant forest land significantly reduced the soil loss; (4) trends of gully erosion intensity and density were not consistent with the change in soil erosion intensity. To our knowledge, this study was one of the first that attempted to integrate gully erosion and hillslope erosion on a watershed scale. The findings of this study promote a better understanding of the spatial coupling relationships between hillslope and gully erosion and similarly indicate that GCM, RS, and GIS can be used efficiently in the hilly black soil region of Northeast China to assess hillslope and gully erosion
No tillage combined with crop rotation improves soil microbial community composition and metabolic activity
No full textSoil microbial community can vary with different agricultural managements, which in turn can affect soil quality. The objective of this work was to evaluate the effects of long-term tillage practice (no tillage (NT) and conventional tillage (CT)) and crop rotation (maize-soybean (MS) rotation and monoculture maize (MM)) on soil microbial community composition and metabolic capacity in different soil layers. Long-term NT increased the soil organic carbon (SOC) and total nitrogen (TN) mainly at the 0-5 cm depth which was accompanied with a greater microbial abundance. The greater fungi-to-bacteria (F/B) ratio was found in NTMS at the 0-5 cm depth. Both tillage and crop rotation had a significant effect on the metabolic activity, with the greatest average well color development (AWCD) value in NTMS soil at all three soil depths. Redundancy analysis (RDA) showed that the shift in microbial community composition was accompanied with the changes in capacity of utilizing different carbon substrates. Therefore, no tillage combined with crop rotation could improve soil biological quality and make agricultural systems more sustainable
Performance Evaluation of Cluster Validity Indices (CVIs) on Multi/Hyperspectral Remote Sensing Datasets
No full textThe number of clusters (i.e., the number of classes) for unsupervised classification has been recognized as an important part of remote sensing image clustering analysis. The number of classes is usually determined by cluster validity indices (CVIs). Although many CVIs have been proposed, few studies have compared and evaluated their effectiveness on remote sensing datasets. In this paper, the performance of 16 representative and commonly-used CVIs was comprehensively tested by applying the fuzzy c-means (FCM) algorithm to cluster nine types of remote sensing datasets, including multispectral (QuickBird, Landsat TM, Landsat ETM+, FLC1, and GaoFen-1) and hyperspectral datasets (Hyperion, HYDICE, ROSIS, and AVIRIS). The preliminary experimental results showed that most CVIs, including the commonly used DBI (Davies-Bouldin index) and XBI (Xie-Beni index), were not suitable for remote sensing images (especially for hyperspectral images) due to significant between-cluster overlaps; the only effective index for both multispectral and hyperspectral data sets was the WSJ index (WSJI). Such important conclusions can serve as a guideline for future remote sensing image clustering applications
Potential effects of tidal flat variations on decomposition and nutrient dynamics of Phragmites australis, Suaeda salsa and Suaeda glauca litter in newly created marshes of the Yellow River estuary, China
No full textSalinity gradient and tidal flooding are two key factors in the newly created marshes of the Yellow River estuary as they are closely correlated with the accretion or erosion of tidal flat. To investigate the potential effects of tidal flat variations on decomposition and nutrient dynamics of Phragmites australis, Suaeda salsa and Suaeda glauca litters in the Yellow River estuary, the natural salinity and flooding gradients in the newly created tidal flat [high marsh (river bank), middle marsh and low marsh] were applied to simulate the variations of salinity and tidal flooding in the three typical halophyte communities. Results showed that the mass losses and decomposition rates of the three halophyte litters differed significantly along salinity and flooding gradients (p S. glauca > S. salsa, while in low salinity and moisture, the order demonstrated S. glauca > S. salsa > P. australis. The C and N concentrations in the three halophytes along salinity and flooding gradients showed different variations, and, with the increasing of salinity and moisture, there was a tendency that the N in P. australis and S. salsa shifted from accumulation to release while those in S. glauca demonstrated strong release at all times. This study also indicated that salinity, tidal inundation and C/N ratios were three important factors affecting the differences in decomposition rates and C and N release patterns of the three halophytes. If the salinity and flooding frequency in P. australis and S. salsa communities were greatly increased, the decomposition rates would increase by 61.88-205.48% and 103.93%, and the C release after 571 days would increase by 40.23-83.49% and 30.12%, respectively; if the salinity and flooding frequency in S. glauca community were significantly decreased, the decomposition rates would decrease by 42.79-44.78% and the C release would decrease by 23.78-27.93%. Differently, if the salinity and flooding frequency in S. glauca community were greatly decreased, the N release would at least decrease by 67.46%; if the salinity and flooding frequency in P. australis and S. salsa communities were significantly increased, the N release only would occur in high salinity and flooding frequency. In recent years, the coastal marsh in the Yellow River estuary has shifted from erosion to accretion with the long-term implementation of "Flow-sediment Regulation Project", and our results provided valuable information for predicting the possible influences of tidal flat variations on decomposition and nutrient dynamics of the three halophytes in future. (C) 2016 Elsevier B.V. All rights reserved
Rapid N2O fluxes at high level of nitrate nitrogen addition during freeze-thaw events in boreal peatlands of Northeast China
No full textFreeze-thaw (FT) events and increasing nitrogen (N) availability may alter N turnover and nitrous oxide (N2O) emissions in permafrost peatlands. However, the responses of N2O emissions to different N levels and additions during FT events are far from clear. We conducted an incubation study to investigate the impacts of different N addition levels (LN: 0.07 mg N g(-1), HN: 0.14 mg N g(-1)) and N addition forms (AC: ammonium chloride, NS: sodium nitrate) on the emissions of N2O under FT and non-freeze-thaw (NFT) conditions in boreal peatlands of Northeast China. Results indicated that the FT condition significantly increased N2O emissions compared with the NFT condition and peaks occurred during thawing. Compared with AC treatments, NS treatments significantly elevated the accumulation of N2O emissions under the FT condition, exhibiting significant differences in different NS levels. N2O emissions were also positively dependent on soil NO3- concentrations to supply nitrate for denitrification. Nitrate-N addition was mainly responsible for the burst of N2O with denitrification as the main process during FT events. Therefore, these results suggest that N2O emissions potentially increase during FT events with increasing nitrate-N deposition in permafrost peatlands, which would contribute to global climate warming. (C) 2016 Elsevier Ltd. All rights reserved
A recessive allele for delayed flowering at the soybean maturity locus E9 is a leaky allele of FT2a, a FLOWERING LOCUS T ortholog
No full textBackground: Understanding the molecular mechanisms of flowering and maturity is important for improving the adaptability and yield of seed crops in different environments. In soybean, a facultative short-day plant, genetic variation at four maturity genes, E1 to E4, plays an important role in adaptation to environments with different photoperiods. However, the molecular basis of natural variation in time to flowering and maturity is poorly understood. Using a cross between early-maturing soybean cultivars, we performed a genetic and molecular study of flowering genes. The progeny of this cross segregated for two maturity loci, E1 and E9. The latter locus was subjected to detailed molecular analysis to identify the responsible gene. Results: Fine mapping, sequencing, and expression analysis revealed that E9 is FT2a, an ortholog of Arabidopsis FLOWERING LOCUS T. Regardless of daylength conditions, the e9 allele was transcribed at a very low level in comparison with the E9 allele and delayed flowering. Despite identical coding sequences, a number of single nucleotide polymorphisms and insertions/deletions were detected in the promoter, untranslated regions, and introns between the two cultivars. Furthermore, the e9 allele had a Ty1/copia-like retrotransposon, SORE-1, inserted in the first intron. Comparison of the expression levels of different alleles among near-isogenic lines and photoperiod-insensitive cultivars indicated that the SORE-1 insertion attenuated FT2a expression by its allele-specific transcriptional repression. SORE-1 was highly methylated, and did not appear to disrupt FT2a RNA processing. Conclusions: The soybean maturity gene E9 is FT2a, and its recessive allele delays flowering because of lower transcript abundance that is caused by allele-specific transcriptional repression due to the insertion of SORE-1. The FT2a transcript abundance is thus directly associated with the variation in flowering time in soybean. The e9 allele may maintain vegetative growth in early-flowering genetic backgrounds, and also be useful as a long-juvenile allele, which causes late flowering under short-daylength conditions, in low-latitude regions
Risk assessment of heavy metals contamination in sediment and aquatic animals in downstream waters affected by historical gold extraction in Northeast China
No full textTo assess the risk of heavy metals contamination on the aquatic ecosystem in downstream waters of a gold field in Northeast China, samples of sediment, fish, shrimp, and mussels were collected to determine heavy metals concentrations. According to I-geo, more attention should be given to Hg, Pb, and Cu pollution in sediment of Weisha River. For aquatic animals, the greatest contents of Hg, Cu, and Pb were found in samples collected from Weisha River, while the maximum values of Zn, Cd, and Cr were found in Hongshi Reservoir, Banmiao River, and Songhua Lake, respectively. The Hg and Pb contents in fish were found in the order of predatory fish > omnivorous fish > herbivorous fish, although for other metals no significant difference was observed among the three trophic levels. The contents of metals in Oriental river prawn and Chinese pond mussel were greater than that in fish, except for Pb. The Target Hazard Quotient and Hazard Index of metals showed that the Carnivorous and Omnivorous fish from Songhua Lake and Hongshi Reservoir, as well as all fish from Banmiao River and Weisha River, were not suitable for consuming in the view of the combined risk of all metals
Seasonal changes in the contribution of root respiration to total soil respiration in a freshwater marsh in Sanjiang Plain, Northeast China
No full textSeparating the two major components of soil respiration, root respiration (Rr) and heterotrophic respiration (Rh), is an important step for understanding and modelling carbon cycling in organic soils. However, few partitioning studies exist regarding wetland ecosystems. For this study, we selected a freshwater marsh on Sanjiang Plain, Northeast China and used a trenching method to determine the contribution of R-r to soil respiration during the two growing seasons in 2010 and 2011. The decomposition rate of dead roots (R-D) was estimated to correct the soil respiration of the trenching plots. The soil respiration rates in the control plot increased from May (288-508 mg CO2 m(-2) h(-1)) to late June (1103 mg CO2 m(-2) h(-1) in 2010) or early July (1278 mg CO2 m(-2) h(-1) in 2011) and later decreased during the last growing season. The soil respiration rate in the trenching plot exhibited a similar pattern of seasonal change, but the rates were lower than in the control plot, except at the beginning of trenching. When considering the dead root decomposition in the trenching plots, the contributions of R-r to total soil respiration in the two growing seasons were estimated to range from 22 to 77 % (2010) and 46 to 81 % (2011). The mean contribution of R-D was approximately 12 % in the growing season of the first year (2010) and later decreased to approximately 6 % in the second year (2011). The contents of soil NH4+-N and NO3--N were significantly greater in the trenching plots than in the control plots. The content of microbial biomass nitrogen tended to increase after trenching for the 0- to 30-cm soil depth. These results indicate that the microbial community may change in the second year, which may affect the estimation of the contribution of root respiration to total soil respiration
Synergistic effect using vermiculite as media with a bacterial biofilm of Arthrobacter sp for biodegradation of di-(2-ethylhexyl) phthalate
No full textVermiculite is one of matrix material used for constructed wetland (CW) for the treatment of municipal wastewater. Arthrobacter sp. strain C21 (CGMCC No. 7671), isolated from a constructed wetland receiving municipal wastewater, forms biofilm on the surface of vermiculite. Di-(2-ethylhexyl) phthalate (DEHP), a typical phthalate pollutant in environment, can be degraded by the biofilm of strain C21 formed on vermiculite. Results of laboratory studies indicated that DEHP was removed from aqueous phase via biodegradation, adsorption by vermiculite, and adsorption by biofilm biomass. Synergistic effect of these three reactions enhanced the overall DEHP removal efficiency. During a batch incubation test with vermiculite and the cell suspension, bacterial adhesion to the media surface occurred within 5 h and the phthalate esters (PEs) removal was due to both biodegradation and vermiculite adsorption. As the biofilm developed on surface of vermiculite (5-36 h), biodegradation became the predominance for PEs removal. As mature biofilm was formed (36-54 h), the adsorption of PEs by biofilm biomass became a main driving force for the removal of PEs from aqueous phase. The content of extracellular polymers (EPS) of the biofilm and DEHP removal performance showed a significant positive correlation (r(p) > 0.86). (C) 2015 Elsevier B.V. All rights reserved