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
文摘分析补骨脂醇提物(Psoraleae Fructus alcohol extract,PFE)化学成分并探讨其促黑色素生成作用机制。采用超高效液相色谱-四级杆飞行时间质谱(UPLC-Q-TOF-MS)对PFE化学成分进行鉴定;观察PFE对斑马鱼黑色素生成的影响;通过实时荧光定量聚合酶链式反应(quantitative real-time PCR,qRT-PCR)考察PFE、补骨脂素和异补骨脂素对小鼠黑色素瘤细胞B16-F10中酪氨酸酶(tyrosinase,Tyr)、酪氨酸酶相关蛋白1(Tyr-related protein 1,Tyrp1)和相关蛋白2(Tyr-related protein 2,Tyrp2)mRNA表达的影响。结果在PFE中共鉴定47个化学成分,其中黄酮类27个,香豆素类10个,单萜酚类8个和其他类2个;发现PFE作用斑马鱼18 hpf(受精后小时,hours post fertilization)后,能明显增加其体内黑色素水平;qRT-PCR结果显示,与对照组相比,PFE能显著增加Tyr和Tyrp2 mRNA的表达,其他给药组均能不同程度地增加Tyr、Tyrp1和Tyrp2 mRNA的表达。
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.
