摘要：
Exploring the relationship between net anthropogenic phosphorus input (NAPI) and soil available P (SAP) content could inform applied issues related to environmental quality and agronomic productivity and increase our knowledge of element biogeochemical cycles. Here, the NAPI was estimated and the SAP content determined in eight counties in subtropical China from 1980 to 2010. It is suggested that the NAPI ranging 318-924 km(-2) yr(-1) in 1980 had increased substantially to 865-3601 km(-2) yr(-1) in 2010 across the eight counties, in which the P fertilizer application was estimated to represent the largest individual source of NAPI, accounting for an average of 36.1-74.6% of the NAPI. The NAPI in agricultural land (NAPIa) was the largest component of the NAPI, and 60.7-77.1% of the NAPIa accumulated in the upper 20 cm layer of agricultural soils, which significantly increased soil total-P (TP) and SAP contents. The increases in SAP, resulting from 10,000 kg P km(-2) of the NAPI(a) (IOPNAPI), were estimated to be 1.61-4.36 mg P kg(-1) in the counties. Both the correlation and variation partitioning analyses (VPAs) suggested that the soil pH and organic matter content (SOM) were the most important factors influencing the variations of IOPNAPI (determination coefficient: 72.5%). Therefore, the contribution of soil pH and SOM should be considered in enriching soil SAP levels and implementing optimal P management strategies to improving the agronomic effectiveness of P fertilization and further reduce the environmental risk of P loss in subtropical region. (C) 2018 Elsevier Ltd. All rights reserved.
摘要：
Successful floral meristem (FM) determinacy is critical for subsequent reproductive development and the plant life cycle. Although the phytohormones cytokinin and auxin interact to coregulate many aspects of plant development, whether and how cytokinin and auxin function in FM determinacy remain unclear. Here, we show that in Arabidopsis thaliana, cytokinin homeostasis is critical for FM determinacy. In this developmental context, auxin promotes the expression of AUXIN RESPONSE FACTOR3 (ARF3) to repress cytokinin activity. ARF3 directly represses the expression of ISOPENTENYLTRANSFERASE (IPT) family genes and indirectly represses LONELY GUY (LOG) family genes, both of which encode enzymes required for cytokinin biosynthesis. ARF3 also directly inhibits the expression of ARABIDOPSIS HISTIDINE KINASE4, a cytokinin receptor gene, resulting in reduced cytokinin activity. Consequently, ARF3 controls cell division by regulating cell cycle gene expression through cytokinin. In flowers, we show that AGAMOUS (AG) dynamically regulates the expression of ARF3 and IPTs, resulting in coordinated regulation of FM maintenance and termination through cell division. Moreover, genome-wide transcriptional profiling revealed both repressive and active roles for ARF3 in early flower development. Our findings establish a molecular link between AG and auxin/cytokinin and shed light on the mechanisms of stem cell maintenance and termination in the FM.
关键词：
Crop morbidity;Biological control agents;Bacterial interactions;Bacterial diversity;Bacterial community structure
摘要：
Bacterial wilt, caused by Ralstonia solanacearum, occurs occasionally during tobacco planting and potentially brings huge economic losses in affected areas. Soil microbes in different management stages play important roles in influencing bacterial wilt incidence. Studies have focused on the impacts of species diversity and composition during cropping periods on disease morbidity; however, the effects of the soil bacterial biomass, species diversity, species succession, and population interactions on morbidity remain unclear during non-cropping periods. In this study, we explored the soil bacterial communities in the non-cropping winter fallow (WF) and cropping late growing (LG) periods under consecutive monoculture systems using 16S ribosomal RNA gene sequencing and qPCR and further analyzed their effects on tobacco bacterial wilt incidence. We found that the bacterial communities in the WF period were significantly different from those in the LG period based on detrended correspondence analysis and dissimilarity tests. Crop morbidity was significantly related to bacterial community structure and to the presence of some genera during WF and LG periods. These genera, such as Arthrobacter, Pseudomonas, Acidobacteria GP6, and Pasteuria, may be potential biological control agents for bacterial wilt. Further analysis indicated that low soil bacterial diversity during the WF period, decrease of bacterial interactions from the WF to LG periods, and low soil biomass during the LG period all have the potential to increase morbidity. In conclusion, an increase of soil bacterial diversity and control of some bacterial abundances in the WF period might be an effective approach in controlling bacterial wilt incidence.
摘要：
In recent years, advanced oxidation processes (AOPs), especially sulfate radical based AOPs have been widely used in various fields of wastewater treatment due to their capability and adaptability in decontamination. Recently, metal-free carbon materials catalysts in sulfate radical production has been more and more concerned because these materials have been demonstrated to be promising alternatives to conventional metal-based catalysts, but the review of metal-free catalysts is rare. The present review outlines the current state of knowledge on the generation of sulfate radical using metal-free catalysts including carbon nanotubes, graphene, mesoporous carbon, activated carbon, activated carbon fiber, nanodiamond. The mechanism such as the radical pathway and non-radical pathway, and factors influencing of the activation of sulfate radical was also be revealed. Knowledge gaps and research needs have been identified, which include the perspectives on challenges related to metal-free catalyst, heterogeneous metal-free catalyst/persulfate systems and their potential in practical environmental remediation. (C) 2017 Elsevier Ltd. All rights reserved.
摘要：
Increased nitrogen (N) concentrations in water bodies have highlighted issues regarding nutrient pollution in agricultural catchments. In this study, the ammonium-N (NH4
+-N), nitrate-N (NO3
−-N), and total N (TN) concentrations were observed in the stream water and groundwater of two contrasting catchments (named Tuojia and Jianshan) in subtropical central China from 2010 to 2014, to determine the rice agriculture impacts on the hydrographic patterns, and N export characteristics of the catchments. The results suggested that greater amounts of stream flow (523.0 vs. 434.7 mm year−1) and base flow (237.6 vs. 142.8 mm year−1) were produced in Tuojia than in Jianshan, and a greater base flow contribution to stream flow and higher frequencies of high-base flow days were observed during the fallow season than during the rice-growing season, indicating that intensive rice agriculture strongly influences the catchment hydrographic pattern. Rice agriculture resulted in moderate N pollution in the stream water and groundwater, particularly in Tuojia. Primarily, rice agriculture increased the NH4
+-N concentration in the stream water; however, it increased the NO3
−-N concentrations in the groundwater, suggesting that the different N species in the paddy fields migrated out of the catchments through distinct hydrological pathways. The average TN loading via stream flow and base flow was greater in Tuojia than in Jianshan (1.72 and 0.58 vs. 0.72 and 0.15 kg N ha−1 month−1, respectively). Greater TN loading via stream flow was observed during the fallow season in Tuojia and during the rice-growing season in Jianshan, and these different results were most likely a result of the higher base flow contribution to TN loading (33.5 vs. 21.3%) and greater base flow enrichment ratio (1.062 vs. 0.876) in Tuojia than in Jianshan. Therefore, the impact of rice agriculture on catchment eco-hydrological processes should be considered when performing water quality protection and treatment in subtropical central China.
通讯机构：
[Meng, DL; Yin, HQ] C;Cent South Univ, Sch Minerals Proc & Bioengn, Changsha 410083, Hunan, Peoples R China.
关键词：
Temperature;Original mineral compositions;Microbial community;Zinc leaching efficiency;Models
摘要：
Temperature and energy resources (e.g., iron, sulfur and organic matter) usually undergo dynamic changes, and play important roles during industrial bioleaching process. Thus, it is essential to investigate their synergistic effects and the changes of their independent effects with simultaneous actions of multi-factors. In this study, we explored the synergistic effects of temperature and original mineral compositions (OMCs, energy resources) on the sphalerite bioleaching process. The microbial community structure was monitored by 16S rRNA gene sequencing technology and showed clear segregation along temperature gradients and Shannon diversity decreased at high temperature. On the contrary, the physicochemical parameters (pH and [Fe3+]) in the leachate were significantly affected by the OMCs. Interestingly, the influence of temperature on zinc recovery was greater at relatively simpler OMCs level, whereas the influence of OMCs was stronger at lower temperature. In addition, using [Fe3+], pH, relative abundances of dominant OTUs of microbial community and temperature as variable parameters, several models were constructed to predict zinc leaching efficiency, providing a possibility to predict the metal recovery efficiency under temperature change and variable energy resources.
摘要：
<jats:title>Summary</jats:title><jats:p>
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<jats:list-item><jats:p><jats:italic><jats:styled-content style="fixed-case">APETALA</jats:styled-content>2</jats:italic> (<jats:italic><jats:styled-content style="fixed-case">AP</jats:styled-content>2</jats:italic>) is best known for its function in the outer two floral whorls, where it specifies the identities of sepals and petals by restricting the expression of <jats:italic><jats:styled-content style="fixed-case">AGAMOUS</jats:styled-content></jats:italic> (<jats:italic><jats:styled-content style="fixed-case">AG</jats:styled-content></jats:italic>) to the inner two whorls in <jats:italic>Arabidopsis thaliana</jats:italic>. Here, we describe a role of <jats:italic><jats:styled-content style="fixed-case">AP</jats:styled-content>2</jats:italic> in promoting the maintenance of floral stem cell fate, not by repressing <jats:italic><jats:styled-content style="fixed-case">AG</jats:styled-content></jats:italic> transcription, but by antagonizing <jats:italic><jats:styled-content style="fixed-case">AG</jats:styled-content></jats:italic> activity in the center of the flower.</jats:p></jats:list-item>
<jats:list-item><jats:p>We performed a genetic screen with <jats:italic>ag‐10</jats:italic> plants, which exhibit a weak floral determinacy defect, and isolated a mutant with a strong floral determinacy defect. This mutant was found to harbor another mutation in <jats:italic><jats:styled-content style="fixed-case">AG</jats:styled-content></jats:italic> and was named <jats:italic>ag‐11</jats:italic>. We performed a genetic screen in the <jats:italic>ag‐11</jats:italic> background to isolate mutations that suppress the floral determinacy defect. Two suppressor mutants were found to harbor mutations in <jats:italic><jats:styled-content style="fixed-case">AP</jats:styled-content>2</jats:italic>.</jats:p></jats:list-item>
<jats:list-item><jats:p>While <jats:italic><jats:styled-content style="fixed-case">AG</jats:styled-content></jats:italic> is known to shut down the expression of the stem cell maintenance gene <jats:italic><jats:styled-content style="fixed-case">WUSCHEL</jats:styled-content></jats:italic> (<jats:italic><jats:styled-content style="fixed-case">WUS</jats:styled-content></jats:italic>) to terminate floral stem cell fate, <jats:italic><jats:styled-content style="fixed-case">AP</jats:styled-content>2</jats:italic> promotes the expression of <jats:italic><jats:styled-content style="fixed-case">WUS</jats:styled-content></jats:italic>.</jats:p></jats:list-item>
<jats:list-item><jats:p><jats:italic><jats:styled-content style="fixed-case">AP</jats:styled-content>2</jats:italic> does not repress the transcription of <jats:italic><jats:styled-content style="fixed-case">AG</jats:styled-content></jats:italic> in the inner two whorls, but instead counteracts <jats:italic><jats:styled-content style="fixed-case">AG</jats:styled-content></jats:italic> activity.</jats:p></jats:list-item>
</jats:list>
</jats:p>
摘要：
As an Agrobacterium tumefaciens T-DNA oncogene, T-6b induces the development of tumors and the enation syndrome in vegetative tissues of transgenic plants. Most of these effects are related to increases in soluble sugar contents. To verify the potential roles of T-6b in the distribution of carbon in developing seeds, not in vegetative tissues, we fused an endosperm-specific promoter to the T-6b gene for expression in transgenic Arabidopsis thaliana plants. The expression of T-6b in reproductive organs did not induce the development of the enation syndrome, and moreover, promoted endosperm expansion, which increased the total seed biomass by more than 10%. Additionally, T-6b also increased oil content in mature seeds by more than 10% accompanied with the decrease of starch and mucilage content at the same time. T-6b enhances seed biomass and helps oil biosynthesis but not polysaccharides in reproductive organs without disturbing vegetative growth and development. Our findings suggest T-6b may be very useful for increasing oil production in biodiesel plants.
摘要：
Plant meristems are responsible for the generation of all plant tissues and organs. Here we show that the transcription factor (TF) FAR-RED ELONGATED HYPOCOTYL3 (FHY3) plays an important role in both floral meristem (FM) determinacy and shoot apical meristem maintenance in Arabidopsis, in addition to its well-known multifaceted roles in plant growth and development during the vegetative stage. Through genetic analyses, we show that WUSCHEL (WUS) and CLAVATA3 (CLV3), two central players in the establishment and maintenance of meristems, are epistatic to FHY3. Using genome-wide ChIP-seq and RNA-seq data, we identify hundreds of FHY3 target genes in flowers and find that FHY3 mainly acts as a transcriptional repressor in flower development, in contrast to its transcriptional activator role in seedlings. Binding motif-enrichment analyses indicate that FHY3 may coregulate flower development with three flower-specific MADS-domain TFs and four basic helix–loop–helix TFs that are involved in photomorphogenesis. We further demonstrate that CLV3, SEPALLATA1 (SEP1), and SEP2 are FHY3 target genes. In shoot apical meristem, FHY3 directly represses CLV3, which consequently regulates WUS to maintain the stem cell pool. Intriguingly, CLV3 expression did not change significantly in fhy3 and phytochrome B mutants before and after light treatment, indicating that FHY3 and phytochrome B are involved in light-regulated meristem activity. In FM, FHY3 directly represses CLV3, but activates SEP2, to ultimately promote FM determinacy. Taken together, our results reveal insights into the mechanisms of meristem maintenance and determinacy, and illustrate how the roles of a single TF may vary in different organs and developmental stages.
摘要：
<jats:p> The indica rice cultivar Xiangzi 3150 (XZ3150) confers a high level of resistance to 95% of the isolates of Magnaporthe oryzae (the agent of rice blast disease) collected in Hunan Province, China. To identify the resistance (R) gene(s) controlling the high level of resistance in this cultivar, we developed 286 F<jats:sub>9</jats:sub> recombinant inbred lines (RILs) from a cross between XZ3150 and the highly susceptible cultivar CO39. Inoculation of the RILs and an F<jats:sub>2</jats:sub> population from a cross between the two cultivars with the avirulent isolate 193-1-1 in the growth chamber indicated the presence of two dominant R genes in XZ3150. A linkage map with 134 polymorphic simple sequence repeat and single feature polymorphism markers was constructed with the genotype data of the 286 RILs. Composite interval mapping (CIM) using the results of 193-1-1 inoculation showed that two major R genes, designated Pi47 and Pi48, were located between RM206 and RM224 on chromosome 11, and between RM5364 and RM7102 on chromosome 12, respectively. Interestingly, the CIM analysis of the four resistant components of the RILs to the field blast population revealed that Pi47 and Pi48 were also the major genetic factors responsible for the field resistance in XZ3150. The DNA markers linked to the new R genes identified in this study should be useful for further fine mapping, gene cloning, and marker-aided breeding of blast-resistant rice cultivars. </jats:p>
