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排序方式: 共有375条查询结果,搜索用时 15 毫秒
1.
Qingfeng Chen Corey S. Westfall Leslie M. Hicks Shiping Wang Joseph M. Jez 《The Journal of biological chemistry》2010,285(39):29780-29786
The GH3 family of acyl-acid-amido synthetases catalyze the ATP-dependent formation of amino acid conjugates to modulate levels of active plant hormones, including auxins and jasmonates. Initial biochemical studies of various GH3s show that these enzymes group into three families based on sequence relationships and acyl-acid substrate preference (I, jasmonate-conjugating; II, auxin- and salicylic acid-conjugating; III, benzoate-conjugating); however, little is known about the kinetic and chemical mechanisms of these enzymes. Here we use GH3-8 from Oryza sativa (rice; OsGH3-8), which functions as an indole-acetic acid (IAA)-amido synthetase, for detailed mechanistic studies. Steady-state kinetic analysis shows that the OsGH3-8 requires either Mg2+ or Mn2+ for maximal activity and is specific for aspartate but accepts asparagine as a substrate with a 45-fold decrease in catalytic efficiency and accepts other auxin analogs, including phenyl-acetic acid, indole butyric acid, and naphthalene-acetic acid, as acyl-acid substrates with 1.4–9-fold reductions in kcat/Km relative to IAA. Initial velocity and product inhibition studies indicate that the enzyme uses a Bi Uni Uni Bi Ping Pong reaction sequence. In the first half-reaction, ATP binds first followed by IAA. Next, formation of an adenylated IAA intermediate results in release of pyrophosphate. The second half-reaction begins with binding of aspartate, which reacts with the adenylated intermediate to release IAA-Asp and AMP. Formation of a catalytically competent adenylated-IAA reaction intermediate was confirmed by mass spectrometry. These mechanistic studies provide insight on the reaction catalyzed by the GH3 family of enzymes to modulate plant hormone action. 相似文献
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Yaoming Li Wangwang Lv Lili Jiang Lirong Zhang Shiping Wang Qi Wang Kai Xue Bowen Li Peipei Liu Huan Hong Wangmu Renzen A Wang Caiyun Luo Zhenhua Zhang Tsechoe Dorji Neslihan Ta Zhezhen Wang Huakun Zhou Yanfen Wang 《Global Change Biology》2019,25(10):3438-3449
Changes in labile carbon (LC) pools and microbial communities are the primary factors controlling soil heterotrophic respiration (Rh) in warming experiments. Warming is expected to initially increase Rh but studies show this increase may not be continuous or sustained. Specifically, LC and soil microbiome have been shown to contribute to the effect of extended warming on Rh. However, their relative contribution is unclear and this gap in knowledge causes considerable uncertainty in the prediction of carbon cycle feedbacks to climate change. In this study, we used a two‐step incubation approach to reveal the relative contribution of LC limitation and soil microbial community responses in attenuating the effect that extended warming has on Rh. Soil samples from three Tibetan ecosystems—an alpine meadow (AM), alpine steppe (AS), and desert steppe (DS)—were exposed to a temperature gradient of 5–25°C. After an initial incubation period, soils were processed in one of two methods: (a) soils were sterilized then inoculated with parent soil microbes to assess the LC limitation effects, while controlling for microbial community responses; or (b) soil microbes from the incubations were used to inoculate sterilized parent soils to assess the microbial community effects, while controlling for LC limitation. We found both LC limitation and microbial community responses led to significant declines in Rh by 37% and 30%, respectively, but their relative contributions were ecosystem specific. LC limitation alone caused a greater Rh decrease for DS soils than AMs or ASs. Our study demonstrates that soil carbon loss due to Rh in Tibetan alpine soils—especially in copiotrophic soils—will be weakened by microbial community responses under short‐term warming. 相似文献
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利用平板对峙法和牛津杯法,从疏花水柏枝、金银花、秋华柳的内生菌中,筛选出1株对稻瘟病菌具有很强抑制作用的菌株JS-1。经生理生化实验和18S rDNAITS序列分析,确定该菌株为黑曲霉(Aspergillus niger)。实验结果表明,JS-1发酵液作用稻瘟病菌后,稻瘟病菌的菌丝变细,分支减少,菌丝基质颜色变浅,作用72 h后干重显著降低。进一步实验表明,该菌产生的活性物质位于其发酵液的乙酸乙酯酯相部位,对稻瘟病病菌抑制率高达96.1%。大田实验数据(天然接种圃)显示,添加该物质后,丰两优4号(中感)和广陆矮4号(易感)叶瘟病情指数分别只有16.25%和32.48%,对稻瘟病的防治取得了很好的效果,说明该菌株具有开发成高效生物农药的巨大潜能。 相似文献
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Cuihai You Yanbing Wang Xingru Tan Bingwei Zhang Tingting Ren Boyu Chen Mengzhen Xu Shiping Chen 《Journal of Plant Ecology》2022,15(5):961
北方半干旱草原生态系统光合参数的季节和年际变异
生态系统表观量子效率(α)、最大光合速率(Pmax)和暗呼吸速率(Rd)不仅反映了生态系统水平 光合生理特征,同时也是碳循环模型中光合过程模拟的关键参数。气候和植被因子都会影 响光合参数的季节和年际变异,但二者在光合参数调控过程中的相对贡献和作用途径尚不清晰。本研究基于连续12年(2006–2017)的涡度相关观测数据,分析了内蒙古半干旱典型草原光合参数的季节和年际变化规律;利用回归分析和结构方程模型(SEM)方法明晰了环境和生理调控的作用途径及相对贡献。结果发现,光合参数(α、Pmax和Rd)均表现出单峰的季节变化趋势,并呈现明显的年际波动。温度(Ta)和土壤含水量(SWC)的变化共同影响光合参数的季节变化,而SWC主导了其年际变异。α和Rd的变化主要由Ta决定,而Pmax的变化主要受SWC的影响。SEM模型分析表明,除了直接作用外,环境因子主要通过影响冠层水平气孔导度(gc)对光合参数和碳同化生理过程进行调控。此外,叶面积指数对光合参数特别是Pmax的季节和年际变异起主要调控作用。以上结果明确了环境和植被共同决定了生态系统水平光合参数的季节和年际变异,并强调了在水分受限的草原生态系统中,植被生理调控在光合碳同化能力和碳汇功能评估中的重要作用。 相似文献
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Ecologic vulnerable areas (EVAs) are the regions where ecosystems are fragile and vulnerable to suffer from degradation with external disturbances, e.g. environmental changes and human activities (Feng et al. 2022; Wang et al. 2019). EVAs in China are widely distributed and account for more than 55% China’s land area (Ministry of Ecology and Environment of the People’s Republic of China 2008). The ecosystem in EVAs, chartered with low stability, weak resistance and high vulnerability, has been experiencing significant degradation owing to the impacts of global climate change and human activities (Bai et al. 2018; Chen et al. 2021; Yu et al. 2022). The EVAs in China are not only the most serious areas of environmental degradation, but also the most poverty-stricken regions (Wang et al. 2019). Harsh environmental condition (drought, low temperature and strong radiation) and limited resource supply (water, soil nutrients, etc.) constrain the vegetation productivity and ecosystem services of EVAs (Li et al. 2021). Climate change adds new challenges with warmer temperatures, changing rainfall regime and increasing frequency of extreme events (drought, heat wave, storms, etc.), which make it is more difficult to predict the changes of ecosystem processes and functions in future scenarios (Piao et al. 2020; Reid et al. 2014).
Carbon and water fluxes are the core ecosystem processes, which is linked to diverse ecosystem services (Lian et al. 2021). Therefore, clarifying the variations and controls of ecosystem carbon and water fluxes is an effective approach to clarifying how ecosystem respond to global change in EVAs (Baldocchi 2020). As the only technique can directly measure the carbon, water and energy fluxes between vegetation and atmosphere, eddy covariance technique has been considered as a standard method for flux observations (Chen et al. 2020). By integrating long-term, eddy covariance measurements over time and space, researches are able to assess ecosystem metabolism at different time scales (hours to decades) (Forzieri et al. 2020; Han et al. 2020; Jung et al. 2017). Eddy covariance measurements also produce information on how ecosystem respond to the changes in climate, which is useful for assessing ecosystem carbon sequestration (Hu et al. 2018), water and energy balance (Forzieri et al. 2020), resource use efficiency (Liu et al. 2019) and ecosystem feedback to climate change (Huang et al. 2019; Piao et al. 2020; Yue et al. 2020). Long-term flux measurements are also vital for detecting the responses of ecosystem functions to extreme events, optimizing and validating models on regional and global scales (Baldocchi 2020). Combining with remote sensing and ecosystem modeling techniques, scientists can upscale and evaluate the functional relations between carbon and water fluxes with environmental variables at high resolution and across diverse spatial/temporal scales (Niu et al. 2017; Xia et al. 2020). 相似文献
8.
Accumulating data have suggested that small RNAs (sRNAs) have important functions in plant responses to pathogen invasion. However, it is largely unknown whether and how sRNAs are involved in the regulation of rice responses to the invasion of Xanthomonas oryzae pv. oryzae (Xoo), which causes bacterial blight, the most devastating bacterial disease of rice worldwide. We performed simultaneous genome-wide analyses of the expression of sRNAs and genes during early defense responses of rice to Xoo mediated by a major disease resistance gene, Xa3/Xa26, which confers durable and race-specific qualitative resistance. A large number of sRNAs and genes showed differential expression in Xa3/Xa26-mediated resistance. These differentially expressed sRNAs include known microRNAs (miRNAs), unreported miRNAs, and small interfering RNAs. The candidate genes, with expression that was negatively correlated with the expression of sRNAs, were identified, indicating that these genes may be regulated by sRNAs in disease resistance in rice. These results provide a new perspective regarding the putative roles of sRNA candidates and their putative target genes in durable disease resistance in rice. 相似文献
9.
Xijia Xu Shiping Xie Xiaomeng Shi Jie Lv Xiaowei Tang Xiaolan Wang Shuiping Lu Mingzhong Wang Xiaobing Zhang Jing Sun Hui Yao 《PloS one》2015,10(12)
Hexanucleotide (GGGGCC) repeat expansion in C9ORF72 (HRE) causes frontotemporal lobar degeneration, frontotemporal dementia–amyotrophic lateral sclerosis, and amyotrophic lateral sclerosis. HRE was also seen in the genomes of patients suffering from several other degenerative diseases. However, whether it is present in the treatment-resistant schizophrenia patients remains unknown. Genotyping 386 patients suffering from treatment-resistant schizophrenia using the method of Repeat-Primed PCR, we reported here that no HRE was detected in the patients of Chinese Han. 相似文献
10.
Shiping Yang Shaomin Lin Qiang Fu Baizhen Cai Fei Kong Guang Huang Fafen Li Han Wang 《PloS one》2015,10(3)