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
目的:探讨孕期恐伤肾对其56日龄仔鼠股骨发育和血清中骨代谢指标的影响,为“恐伤肾,肾主骨”理论提供实验依据。方法:选取基线一致的孕0.5 d Wistar大鼠20只按照随机数字表法分为模型组和对照组,模型组运用旁观电击法建立妊娠期恐伤大...目的:探讨孕期恐伤肾对其56日龄仔鼠股骨发育和血清中骨代谢指标的影响,为“恐伤肾,肾主骨”理论提供实验依据。方法:选取基线一致的孕0.5 d Wistar大鼠20只按照随机数字表法分为模型组和对照组,模型组运用旁观电击法建立妊娠期恐伤大鼠模型,对照组正常喂养,分别在孕7 d、14 d和20 d采用旷场实验对孕鼠进行行为学测试,在孕20 d采用酶联免疫法(ELISA)检测其血清糖皮质激素(GC)水平并评价建模情况。仔鼠延续母鼠分组,利用旷场实验对56日龄仔鼠进行行为学测试,采集血清和双后肢股骨样本并检测钙磷水平。用ELISA检测血清中I型胶原羧基端交联肽(CTX-I)、骨源性碱性磷酸酶(BALP)和I型前胶原氨基端原肽(PINP)水平。结果:与对照组比较,模型组孕鼠在孕7 d、14 d和20 d的旷场实验水平得分、垂直得分均降低(P<0.05),孕20 d GC水平显著升高(P<0.05);与对照组比较,模型组56日龄仔鼠旷场实验水平得分、垂直得分均降低(P<0.05),体质量减轻,肾脏质量和脏器系数均降低(P<0.05);双后肢股骨干重降低(P<0.05),股骨钙磷含量也均降低(P<0.05),血清中钙含量降低(P<0.05),CTX-I水平显著升高(P<0.05),BALP和PINP的水平均降低(P<0.05)。结论:恐伤孕鼠可影响其子代的股骨发育和代谢,恐惧刺激可以引起骨发育损伤,主要表现为钙磷代谢紊乱和骨吸收增强。展开更多
以天然产物白杨素为原料,与多种α-溴代苯乙酮反应制得6种7-(2-羰基-2-苯基)乙氧基白杨素衍生物(2a^2f);2a^2f与盐酸羟胺进行肟化反应,合成了6种新型的Z-构型7-(2-羟亚胺-2-苯基)乙氧基白杨素衍生物(3a^3f),其结构经1 H NMR,13 C NMR,IR...以天然产物白杨素为原料,与多种α-溴代苯乙酮反应制得6种7-(2-羰基-2-苯基)乙氧基白杨素衍生物(2a^2f);2a^2f与盐酸羟胺进行肟化反应,合成了6种新型的Z-构型7-(2-羟亚胺-2-苯基)乙氧基白杨素衍生物(3a^3f),其结构经1 H NMR,13 C NMR,IR和HR-MS(ESI)表征。采用MTT法测试了3a^3f对人宫颈癌细胞株Hela和人胃癌细胞SGC-7901的体外抑制活性。结果表明:化合物3b和3e对Hela的抑制作用较好,IC 50分别为18.2和17.4μmol·L^-1。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
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.
文摘以天然产物白杨素为原料,与多种α-溴代苯乙酮反应制得6种7-(2-羰基-2-苯基)乙氧基白杨素衍生物(2a^2f);2a^2f与盐酸羟胺进行肟化反应,合成了6种新型的Z-构型7-(2-羟亚胺-2-苯基)乙氧基白杨素衍生物(3a^3f),其结构经1 H NMR,13 C NMR,IR和HR-MS(ESI)表征。采用MTT法测试了3a^3f对人宫颈癌细胞株Hela和人胃癌细胞SGC-7901的体外抑制活性。结果表明:化合物3b和3e对Hela的抑制作用较好,IC 50分别为18.2和17.4μmol·L^-1。
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.
