SrUGT76G1,the most well-studied diterpene glycosyltransferase in Stevia rebaudiana,is key to the biosynthesis of economically important steviol glycosides(SGs).However,the molecular regulatory mechanism of SrUGT76G1 h...SrUGT76G1,the most well-studied diterpene glycosyltransferase in Stevia rebaudiana,is key to the biosynthesis of economically important steviol glycosides(SGs).However,the molecular regulatory mechanism of SrUGT76G1 has rarely been explored.In this study,we identified a MYB transcription factor,SrMYB1,using a yeast one-hybrid screening assay.SrMYB1 belongs to the typical R2R3-type MYB protein and is specifically localized in the nucleus with strong transactivation activity.The transcript of SrMYB1 is predominantly accumulated in flowers,but is also present at a lower level in leaves.Yeast one-hybrid and electrophoretic mobility shift assays verified that SrMYB1 binds directly to the MYB binding sites in the F4-3 fragment(+50–(–141))of the SrUGT76G1 promoter.Furthermore,we found that SrMYB1 could significantly repress the expression of SrUGT76G1 in both epidermal cells of tobacco leaves and stevia callus.Taken together,our results demonstrate that SrMYB1 is an essential upstream regulator of SrUGT76G1 and provide novel insight into the regulatory network for the SGs metabolic pathway in S.rebaudiana.展开更多
The steviol glycosides(SGs)in stevia(Stevia rebaudiana Bertoni)leaves are becoming increasingly valuable due to its high sweetness but low calorific value,which is driving the development of stevia commercial cultivat...The steviol glycosides(SGs)in stevia(Stevia rebaudiana Bertoni)leaves are becoming increasingly valuable due to its high sweetness but low calorific value,which is driving the development of stevia commercial cultivation.Optimizing fertilization management can effectively increase SGs productivity,but knowledge on the relationship between potassium(K)fertilization and SGs production is still lacking.In this study,pot experiments were conducted in order to investigate the effect of K deficiency on SGs synthesis in stevia leaves,as well as the underlying mechanisms.Our results showed that when compared with standard K fertilization,K deficiency treatment has no significant effect on the biomass of stevia plant grown in a given soil with high K contents.However,K deficiency critically decreased leaf SGs contents as well as the expression of SGs synthesis-related genes.The contents of different sugar components decreased and the activities of sugar metabolism-related enzymes were inhibited under the K deficiency condition.Moreover,spraying sucrose on the leaves of stevia seedlings diminished the inhibitory effect caused by K deficiency.Our results also revealed the significant positive correlations between sucrose,glucose and SGs contents.Overall,our results suggest that K deficiency would suppress the synthesis of SGs in stevia leaves,and this effect may be mediated by the leaf sugar metabolism.Our findings provide new insights into the improvement of SGs production potential.展开更多
目的从文献计量学的角度分析肝移植术麻醉的研究热点及趋势,探究肝移植术麻醉的发展及现状。方法检索Web of Science(核心合集)数据库2012至2021年肝移植术麻醉的文献,利用文献计量学方法对年出版文章数量、高发文期刊、高被引论文方面...目的从文献计量学的角度分析肝移植术麻醉的研究热点及趋势,探究肝移植术麻醉的发展及现状。方法检索Web of Science(核心合集)数据库2012至2021年肝移植术麻醉的文献,利用文献计量学方法对年出版文章数量、高发文期刊、高被引论文方面进行统计分析。运用VOSviewer软件进行主题词共现聚类视图和标签视图分析。结果共纳入肝移植术麻醉研究文献469篇,年出版文献量呈波状趋势,其中《TRANSPLANTATION PROCEEDINGS》是主要文献来源。发表在《BRTISH JOURNAL OF ANAESTHESIA》的Perioperative acute kidney injury是引用频次最高的文献。关键词共现聚类分析肝移植术麻醉研究热点,包括麻醉药物器官保护的基础研究、术前评估、肝移植合并其他器官移植、围术期器官并发症、肝移植患者麻醉药理学、围术期容量管理,其中体外膜肺氧合、血栓弹力图、肝缺血、疼痛管理、围术期管理等越来越受到关注。结论肝移植术麻醉的研究热点从基础研究转向整个围术期器官功能保护的研究,为指导肝移植术麻醉、提高术后生存率提供依据。展开更多
The native point defect states in ZnO have been calculated by using a full-potential linear muffin-tin orbital method. The results show that Zn vacancy and O interstitial produce the shallow acceptor levels above the ...The native point defect states in ZnO have been calculated by using a full-potential linear muffin-tin orbital method. The results show that Zn vacancy and O interstitial produce the shallow acceptor levels above the valence band. The O vacancy produces a deep donor level, while Zn interstitial produces a shallow donor level, both below the conduction band. The Zn interstitial is the main factor which induces the native n-type conductivity in ZnO.展开更多
基金supported by the National Natural Science Foundation of China(31901597)the Natural Science Foundation of Jiangsu Province,China(BK20201243)。
文摘SrUGT76G1,the most well-studied diterpene glycosyltransferase in Stevia rebaudiana,is key to the biosynthesis of economically important steviol glycosides(SGs).However,the molecular regulatory mechanism of SrUGT76G1 has rarely been explored.In this study,we identified a MYB transcription factor,SrMYB1,using a yeast one-hybrid screening assay.SrMYB1 belongs to the typical R2R3-type MYB protein and is specifically localized in the nucleus with strong transactivation activity.The transcript of SrMYB1 is predominantly accumulated in flowers,but is also present at a lower level in leaves.Yeast one-hybrid and electrophoretic mobility shift assays verified that SrMYB1 binds directly to the MYB binding sites in the F4-3 fragment(+50–(–141))of the SrUGT76G1 promoter.Furthermore,we found that SrMYB1 could significantly repress the expression of SrUGT76G1 in both epidermal cells of tobacco leaves and stevia callus.Taken together,our results demonstrate that SrMYB1 is an essential upstream regulator of SrUGT76G1 and provide novel insight into the regulatory network for the SGs metabolic pathway in S.rebaudiana.
基金supported by the Natural Science Foundation of Jiangsu Province,China(BK20180312)the Jiangsu Key Laboratory for the Research and Utilization of Plant Resources,China(JSPKLB201810)the Natural Science Foundation of Shanxi Province,China(201901D111230)。
文摘The steviol glycosides(SGs)in stevia(Stevia rebaudiana Bertoni)leaves are becoming increasingly valuable due to its high sweetness but low calorific value,which is driving the development of stevia commercial cultivation.Optimizing fertilization management can effectively increase SGs productivity,but knowledge on the relationship between potassium(K)fertilization and SGs production is still lacking.In this study,pot experiments were conducted in order to investigate the effect of K deficiency on SGs synthesis in stevia leaves,as well as the underlying mechanisms.Our results showed that when compared with standard K fertilization,K deficiency treatment has no significant effect on the biomass of stevia plant grown in a given soil with high K contents.However,K deficiency critically decreased leaf SGs contents as well as the expression of SGs synthesis-related genes.The contents of different sugar components decreased and the activities of sugar metabolism-related enzymes were inhibited under the K deficiency condition.Moreover,spraying sucrose on the leaves of stevia seedlings diminished the inhibitory effect caused by K deficiency.Our results also revealed the significant positive correlations between sucrose,glucose and SGs contents.Overall,our results suggest that K deficiency would suppress the synthesis of SGs in stevia leaves,and this effect may be mediated by the leaf sugar metabolism.Our findings provide new insights into the improvement of SGs production potential.
文摘目的从文献计量学的角度分析肝移植术麻醉的研究热点及趋势,探究肝移植术麻醉的发展及现状。方法检索Web of Science(核心合集)数据库2012至2021年肝移植术麻醉的文献,利用文献计量学方法对年出版文章数量、高发文期刊、高被引论文方面进行统计分析。运用VOSviewer软件进行主题词共现聚类视图和标签视图分析。结果共纳入肝移植术麻醉研究文献469篇,年出版文献量呈波状趋势,其中《TRANSPLANTATION PROCEEDINGS》是主要文献来源。发表在《BRTISH JOURNAL OF ANAESTHESIA》的Perioperative acute kidney injury是引用频次最高的文献。关键词共现聚类分析肝移植术麻醉研究热点,包括麻醉药物器官保护的基础研究、术前评估、肝移植合并其他器官移植、围术期器官并发症、肝移植患者麻醉药理学、围术期容量管理,其中体外膜肺氧合、血栓弹力图、肝缺血、疼痛管理、围术期管理等越来越受到关注。结论肝移植术麻醉的研究热点从基础研究转向整个围术期器官功能保护的研究,为指导肝移植术麻醉、提高术后生存率提供依据。
基金Supported by the National Natural Science Foundation of China under Grant Nos.59872037 and 19874057.
文摘The native point defect states in ZnO have been calculated by using a full-potential linear muffin-tin orbital method. The results show that Zn vacancy and O interstitial produce the shallow acceptor levels above the valence band. The O vacancy produces a deep donor level, while Zn interstitial produces a shallow donor level, both below the conduction band. The Zn interstitial is the main factor which induces the native n-type conductivity in ZnO.
