关键词：
Rice;Cd content;Bacterial community;Soil Cd species;Soil nutrient;Contaminated soil remediation
摘要：
Microorganisms have a significant role in regulating the absorption and transportation of Cd in the soil-plant system. However, the mechanism by which key microbial taxa play a part in response to the absorption and transportation of Cd in rice under Cd stress requires further exploration. In this study, the cadmium-tolerant endophytic bacterium Herbaspirillum sp. R3 (R3) and Fe-Mn-modified biochar (Fe-Mn) were, respectively, applied to cadmium-contaminated rice paddies to investigate the effects of key bacterial taxa in the soil-rice system on the absorption and transportation of Cd in rice under different treatments. The results showed that both R3 and Fe-Mn treatments considerably decreased the content of cadmium in roots, stems and leaves of rice at the peak tillering stage by 17.24-49.28% in comparison to the control (CK). The cadmium content reduction effect of R3 treatment is better than that of Fe-Mn treatment. Further analysis revealed that the key bacterial taxa in rice roots under R3 treatment were Sideroxydans and Actinobacteria, and that their abundance showed a substantial positive correlation and a significant negative correlation with the capacity of rice roots to assimilate Cd from the surroundings, respectively. The significant increase in soil pH under Fe-Mn treatment, significant reduction in the relative abundances of Acidobacteria, Verrucomicrobia, Subdivision3 genera incertae sedis, Sideroxydans, Geobacter, Gp1, and Gp3, and the significant increase in the relative abundance of Thiobacillus among the soil bacterial taxa may be the main reasons for the decrease in available Cd content of the soil. In addition, both the R3 and Fe-Mn treatments showed some growth-promoting effects on rice, which may be related to their promotion of transformations of soil available nutrients. This paper describes the possible microbial mechanisms by which strain R3 and Fe-Mn biochar reduce Cd uptake in rice, providing a theoretical basis for the remediation of Cd contamination in rice and soil by utilizing key microbial taxa.
关键词：
Deep tillage;Spatial homogenization;Soil compaction;Bacterial community;Compositional stability;Homogeneous selection
摘要：
The pressures from machinery use and continuous agricultural production practices exacerbate soil compaction. Deep tillage (DT) can reduce subsoil compaction, but the spatial composition patterns and community assembly mechanisms of subsoil vs. topsoil bacteria mediated by DT are unknown. Here, we collected soil profile samples from 18 agricultural fields within a multiple cropping area of southern China to investigate the status of soil compaction. The effects of DT on soil physicochemical properties and bacterial communities at different soil depths were investigated by establishing three long-term experimental sites, and the spatial composition mechanisms of the bacterial community were preliminarily explored. Our results showed that soil compaction occurred at soil depths greater than 20 cm, as evidenced by higher soil bulk density, and sharp decreases in water and nutrient contents and bacterial community diversity. Although the ameliorative effect of DT on deep soil compaction diminished in the fourth year, the water and organic matter content and bacterial alpha diversity remained high. DT resulted in a more homogeneous bacterial community across the soil profile in terms of community similarity and compositional stability, along with increased alpha diversity, all of which were associated with reduced heterogeneity in the soil variables, increased soil organic matter content, and the importance of homogeneous selection in the community assembly mechanism. Additionally, the homogenization of bacterial communities under DT may promote enhancement of bacterial network complexity and stability. Collectively, our findings reveal the importance of deep tillage for deep soil improvement and spatial homogenization of bacterial communities, which has far-reaching implications for comprehensively understanding the spatial dynamics and assembly mechanisms of tillage-mediated soil microbial communities in agroecosystems.
作者机构：
[Peng Li] Hunan Soil and Fertilizer Institute, Hunan Academy of Agricultural Sciences, Changsha, China;[Yunhe Tian; Meijie Tian; Xinyu Chen; Ruiwen Hu; Tian Qin; Zhenxie Yi; Hejun Ao; Juan Li] College of Agronomy, Hunan Agricultural University, Changsha, China;[Kun Yang; Yongjun Liu; Shuguang Peng] Hunan Tobacco Science Institute, Changsha, China;[Yi Zhu] Hunan Tobacco Company Changde Branch, Changde, China;[Zhixuan Liu] Hunan Rice Research Institute, Hunan Academy of Agricultural Sciences, Changsha, China
通讯机构：
[Zhixuan Liu] H;[Hejun Ao; Juan Li] C;Hunan Rice Research Institute, Hunan Academy of Agricultural Sciences, Changsha, China<&wdkj&>College of Agronomy, Hunan Agricultural University, Changsha, China<&wdkj&>College of Agronomy, Hunan Agricultural University, Changsha, China
摘要：
The use of nitrogen-fixing bacteria in agriculture is increasingly recognized as a sustainable method to boost crop yields, reduce chemical fertilizer use, and improve soil health. However, the microbial mechanisms by which inoculation with nitrogen-fixing bacteria enhance rice production remain unclear. In this study, rice seedlings were inoculated with the nitrogen-fixing bacterium R3 (Herbaspirillum) at the rhizosphere during the seedling stage in a pot experiment using paddy soil. We investigated the effects of such inoculation on nutrient content in the rhizosphere soil, plant growth, and the nitrogen-fixing microbial communities within the rhizosphere and endorhizosphere. The findings showed that inoculation with the R3 strain considerably increased the amounts of nitrate nitrogen, ammonium nitrogen, and available phosphorus in the rhizosphere by 14.77%, 27.83%, and 22.67%, respectively, in comparison to the control (CK). Additionally, the theoretical yield of rice was enhanced by 8.81% due to this inoculation, primarily through a 10.24% increase in the effective number of rice panicles and a 4.14% increase in the seed setting rate. Further analysis revealed that the structure of the native nitrogen-fixing microbial communities within the rhizosphere and endorhizosphere were altered by inoculation with the R3 strain, significantly increasing the α-diversity of the communities. The relative abundance of key nitrogen-fixing genera such as Ralstonia, Azotobacter, Geobacter, Streptomyces, and Pseudomonas were increased, enhancing the quantity and community stability of the nitrogen-fixing community. Consequently, the nitrogen-fixing capacity and sustained activity of the microbial community in the rhizosphere soil were strengthened. Additionally, the expression levels of the nitrogen absorption and transport-related genes OsNRT1 and OsPTR9 in rice roots were upregulated by inoculation with the R3 strain, potentially contributing to the increased rice yield. Our study has revealed the potential microbial mechanisms through which inoculation with nitrogen-fixing bacteria enhances rice yield. This finding provides a scientific basis for subsequent agricultural practices and is of critical importance for increasing rice production and enhancing the ecosystem services of rice fields.
摘要：
Cadmium (Cd) contamination in rice (Oryza sativa) is particularly problematic due to its high risk to human health. Investigating the hidden roles of seed endophytes of rice in influencing Cd accumulation is essential to comprehensively understand the effects of biotic and abiotic factors to food security. Here, the content of Cd in soils and rice (Huanghuazhan) seeds from 19 sites along the Yangtze River exhibited considerable differences. From a biotic perspective, we observed the dominant endophytic bacteria, Stenotrophomonas (7.25 %), contribute to Cd control of rice (below 0.2mg kg(-1)). Partial Least Squares (PLS) analysis further suggested that Enterobacteriaceae (15.48 %), altitude and pH were found to be the strong variables that might reduce the Cd uptake of rice. In contrast, Cytophagaceae (0.58 %), latitude and mean annual air pressure had the opposite effect. In pot experiments, after respectively inoculating the isolated endophytic bacteria Stenotrophomonas T4 and Enterobacter R1, N1 (f_Enterobacteriaceae), the Cd contents in shoot decreased by 47.6 %, 21.9 % and 33.0 % compared to controls. The distribution of Cd resistant genes (e.g., czcABC, nccAB, cznA) of Stenotrophomonas, Enterobacteriaceaea and Cytophagaceae further suggested their distinct manners in influencing the Cd uptake of rice. Overall, this study provides new insights into the food security threatened by globally widespread Cd pollution.
期刊：
FRONTIERS IN PLANT SCIENCE,2023年14:1277682 ISSN：1664-462X
通讯作者：
Yuan, M.M.;Li, J.;Meng, D.
作者机构：
School of Minerals Processing and Bioengineering, Central South University, Changsha, China;Key Laboratory of Biometallurgy, Ministry of Education, Changsha, China;[Yuan, Mengting Maggie] Department of Environmental Science, Policy, and Management, University of California, Berkeley, Berkeley, CA, United States;[Li, Juan] College of Agronomy, Hunan Agricultural University, Changsha, China;[Meng, Delong] School of Minerals Processing and Bioengineering, Central South University, Changsha, China, Key Laboratory of Biometallurgy, Ministry of Education, Changsha, China
通讯机构：
[Meng, D.] S;[Yuan, M.M.] D;[Li, J.] C;College of Agronomy, China;Department of Environmental Science, United States
摘要：
In recent years, the problem of Cd pollution in paddy fields has become more and more serious, which seriously threatens the safe production of food crops and human health. Using microorganisms to reduce cadmium pollution in rice fields is a green, safe and efficient method, the complicated interactions between the microbes in rice roots throughout the process of cadmium absorption by rice roots are poorly understood. In this investigation, a hydroponic pot experiment was used to examine the effects of bacteria R3 (Herbaspirillum sp) and T4 (Bacillus cereus) on cadmium uptake and the endophytic bacterial community in rice roots. The results showed that compared with CK (Uninoculated bacterial liquid), the two strains had significant inhibitory or promotive effects on cadmium uptake in rice plant, respectively. Among them, the decrease of cadmium content in rice plants by R3 strain reached 78.57-79.39%, and the increase of cadmium content in rice plants by T4 strain reached 140.49-158.19%. Further investigation showed that the cadmium content and root cadmium enrichment coefficient of rice plants were significantly negatively correlated with the relative abundances of Burkholderia and Acidovorax, and significantly positively correlated with the relative abundances of Achromobacter, Agromyces and Acidocella. Moreover, a more complex network of microbes in rice roots inhibited rice plants from absorbing cadmium. These results suggest that cadmium uptake by rice plants is closely related to the endophytic bacterial community of roots. This study provides a reference scheme for the safe production of crops in cadmium contaminated paddies and lays a solid theoretical foundation for subsequent field applications.
摘要：
World-wide, rice (Oryza sativa L.) is an important food source, and its production is often adversely affected by salinity. Therefore, to ensure stable rice yields for global food security, it is necessary to understand the salt tolerance mechanism of rice. The present study focused on the expression pattern of the rice mismatch repair gene post-meiotic segregation 1 (OsPMS1), studied the physiological properties and performed transcriptome analysis of ospms1 mutant seedlings in response to salt stress. Under normal conditions, the wild-type and ospms1 mutant seedlings showed no significant differences in growth and physiological indexes. However, after exposure to salt stress, compared with wild-type seedlings, the ospms1 mutant seedlings exhibited increased relative water content, relative chlorophyll content, superoxide dismutase (SOD) activity, K(+) and abscisic acid (ABA) content, and decreased malondialdehyde (MDA) content, Na(+) content, and Na(+)/K(+) ratio, as well as decreased superoxide anion (O(2)(-)) and hydrogen peroxide (H(2)O(2)) accumulation. Gene ontology (GO) analysis of the differentially expressed genes (DEGs) of ospms1 mutant seedlings treated with 0 mM and 150 mM NaCl showed significant enrichment in biological and cytological processes, such as peroxidase activity and ribosomes. The Kyoto Encyclopedia of Genes and Genomes (KEGG) metabolic pathway analysis showed that the DEGs specifically enriched ascorbate and aldarate metabolism, flavone and flavonol biosynthesis, and glutathione metabolism pathways. Further quantitative real-time reverse transcription-PCR (qRT-PCR) analysis revealed significant changes in the transcription levels of genes related to abscisic acid signaling (OsbZIP23, OsSAPK6, OsNCED4, OsbZIP66), reactive oxygen scavenging (OsTZF1, OsDHAR1, SIT1), ion transport (OsHAK5), and osmoregulation (OsLEA3-2). Thus, the study's findings suggest that the ospms1 mutant tolerates salt stress at the seedling stage by inhibiting the accumulation of reactive oxygen species, maintaining Na(+) and K(+) homeostasis, and promoting ABA biosynthesis.
通讯机构：
[Yan, QY; He, ZL ] S;Sun Yat Sen Univ, Sch Environm Sci & Engn, Southern Marine Sci & Engn Guangdong Lab Zhuhai, State Key Lab Biocontrol,Environm Microbi Res Ctr, Guangzhou 510006, Peoples R China.;Southern Marine Sci & Engn Guangdong Lab Zhuhai, Zhuhai 519080, Peoples R China.
关键词：
Community function;Community stability;Denitrification;Phylogenetic diversity;Species interaction;Synthetic microbial community
摘要：
Denitrification is an important process of the global nitrogen cycle as some of its intermediates are environmentally important or related to global warming. However, how the phylogenetic diversity of denitrifying communities affects their denitrification rates and temporal stability remains unclear. Here we selected denitrifiers based on their phylogenetic distance to construct two groups of synthetic denitrifying communities: one closely related (CR) group with all strains from the genus Shewanella and the other distantly related (DR) group with all constituents from different genera. All synthetic denitrifying communities (SDCs) were experimentally evolved for 200 generations. The results showed that high phylogenetic diversity followed by experimental evolution promoted the function and stability of synthetic denitrifying communities. Specifically, the productivity and denitrification rates were significantly (P < 0.05) higher with Paracocus denitrificans as the dominant species (since the 50th generation) in the DR community than those in the CR community. The DR community also showed significantly (t = 7.119, df = 10, P < 0.001) higher stability through overyielding and asynchrony of species fluctuations, and showed more complementarity than the CR group during the experimental evolution. This study has important implications for applying synthetic communities to remediate environmental problems and mitigate greenhouse gas emissions.
摘要：
<jats:title>Abstract</jats:title><jats:p>Tumor necrosis factor receptor‐associated factor (TRAF) proteins are conserved in higher eukaryotes and play key roles in transducing cellular signals across different organelles. They are characterized by their C‐terminal region (TRAF‐C domain) containing seven to eight anti‐parallel β‐sheets, also known as the meprin and TRAF‐C homology (MATH) domain. Over the past few decades, significant progress has been made toward understanding the diverse roles of TRAF proteins in mammals and plants. Compared to other eukaryotic species, the <jats:italic>Arabidopsis thaliana</jats:italic> and rice (<jats:italic>Oryza sativa</jats:italic>) genomes encode many more TRAF/MATH domain‐containing proteins; these plant proteins cluster into five classes: TRAF/MATH‐only, MATH‐BPM, MATH‐UBP (ubiquitin protease), Seven in absentia (SINA), and MATH‐Filament and MATH‐PEARLI‐4 proteins, suggesting parallel evolution of TRAF proteins in plants. Increasing evidence now indicates that plant TRAF proteins form central signaling networks essential for multiple biological processes, such as vegetative and reproductive development, autophagosome formation, plant immunity, symbiosis, phytohormone signaling, and abiotic stress responses. Here, we summarize recent advances and highlight future prospects for understanding on the molecular mechanisms by which TRAF proteins act in plant development and stress responses.</jats:p>
作者机构：
[黄弘毅] College of Agronomy, Hunan Agricultural University, Changsha, 410128, China;[薛寒光; 何岳巍] Hunan BISEN Environmental and Energy Co., Ltd., Changsha, 410100, China;[韩睿] Qinghai Key Laboratory of Vegetable Genetics and Physiology, Academy of Agriculture and Forestry Sciences, Qinghai University, Xining, 810016, China;[彭星] Hunan United Kitchen Waste Treatment Co., Ltd., Changsha, 410022, China;[徐建雪; 黎娟] College of Agronomy, Hunan Agricultural University, Changsha, 410128, China<&wdkj&>Hunan BISEN Environmental and Energy Co., Ltd., Changsha, 410100, China
通讯机构：
College of Agronomy, Hunan Agricultural University, Changsha, China
作者机构：
[田祥珅; 郑卜凡; 周启运; 田丽君; 龚嘉蕾; 黎娟] Agricultural College, Hunan Agricultural University, China;[彭新辉; 荊永锋] Technology R&D Center, Hunan China Tobacco Industry Co. LTD, China;[吴涛; 李正风] Yunnan China Tobacco Industry Co., Ltd., Raw Materials Department, 367 Hong jin Road, Kunming, 650231, China;[李正风] Key Laboratory of Tobacco Chemistry of Yunnan Province, Technical Center of Yunnan China Tobacco Industry Co., Ltd., 367 Hong jin Road, Kunming, 650231, China
通讯机构：
[Li, J.] A;Agricultural College, Hunan Agricultural University, China
期刊：
JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY,2021年69(19):5452-5462 ISSN：0021-8561
通讯作者：
Liqun Rao<&wdkj&>Qiming Wang
作者机构：
[Chen, Yanchao; Zhou, Chi; Pan, Weisong; Wang, Qiming; Zhou, Ting; Xu, Minhui; Liu, Chuwei; Rao, Liqun] Hunan Agr Univ, Coll Biosci & Biotechnol, Changsha 410128, Peoples R China.;[Chen, Yanchao; Zhou, Chi; Wang, Qiming; Zhou, Ting; Xu, Minhui; Liu, Chuwei; Rao, Liqun] Hunan Agr Univ, Hunan Engn Lab Good Agr Practice & Comprehens Uti, Changsha 410128, Peoples R China.;[Peng, Qi] Jiangsu Acad Agr Sci, Inst Ind Crops, Key Lab Cotton & Rapeseed, Minist Agr, Nanjing 210014, Peoples R China.;[Peng, Qi] Jiangsu Univ, Inst Life Sci, Zhenjiang 212013, Peoples R China.;[Wu, Chuan] Cent South Univ, Sch Met & Environm, Changsha 410083, Peoples R China.
通讯机构：
[Liqun Rao; Qiming Wang] C;College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha 410128, China<&wdkj&>Hunan Engineering Laboratory for Good Agricultural Practice and Comprehensive Utilization of Famous-Region Medicinal Plants, Hunan Agricultural University, Changsha 410128, China
作者机构：
[Zhai Z.; 唐春闺] Hunan Changsha Municipal Tobacco Company, Changsha, 410011, China;[彭孟祥; 黎娟; 钟越峰] Liuyang Branch of Changsha Municipal Tobacco Company, Liuyang, 410300, China;[黎娟] College of Agronomy, Hunan Agricultural University, Changsha, 410128, China
通讯机构：
[Li, J.] C;College of Agronomy, China
关键词：
烟稻轮作区;土壤微量元素;容重;有效性评价;回归分析
摘要：
[目的]探明湖南烟稻轮作区0～50 cm 土层有效态微量元素Cu、Zn、Fe和Mn含量特征,并了解其与容重的关系.[方法]采集了郴州、衡阳和长沙3个烟稻轮作区150个土壤剖面样品,分析了不同土层微量元素分布特征、丰缺状况和有效性指数,明确了微量元素与容重的关系.[结果](1)0～10cm 土层有效态Cu、Zn、Fe和Mn含量最高,随土层加深而递减;Cu、Zn、Fe和Mn含量达中等及以上水平的土壤样品分别占98.67％、56.67％、69.33％和56.67％.(2)0～50 cm 土层微量元素综合有效性指数自上而下存在逐层递减的规律,20～30cm 土层下降幅度最大.(3)20～50 cm 土层Cu、Zn和Mn含量与容重呈显著负相关,相关性随土层加深表现出增强的趋势.[结论]容重是湖南烟稻轮作区非表层土壤微量元素有效性提高的限制因素之一.
