As contamination is one of important factors to Panax notoginseng quality and safety. Saponin is one of important compounds with the medicinal values of P. notoginseng. The impact of soil As on production of saponin o...As contamination is one of important factors to Panax notoginseng quality and safety. Saponin is one of important compounds with the medicinal values of P. notoginseng. The impact of soil As on production of saponin of P. notoginseng knew very little. This study was performed to determine content and heterogeneity of saponins from P. notoginseng and its mechanisms upon treatments with different concentration levels of As in soil. Plants of P. notoginseng were treated with arsenic [As (V)] at 0, 20, 80, 140, 20 and 260 mg/kg concentration levels which were supplied as sodium arsenate (Na<sub>3</sub>AsO<sub>4</sub>)<sub>.</sub> These experimental plants were grown in shade condition in a greenhouse. Plants were harvested at vigorous vegetative growth and fruit ripening stages, separately. Effects of As treatments on saponin content, and heterogeneity of monomers in the mixtures of notoginesenosides and ginsenosides, enzymatic activity and gene expression level of squalene synthetase were determined for rhizome and main root tissues. Results show that:(1) Of all the As treatments from the lowest to the highest concentration levels, the As content in both rhizome and main roots from As-treated plants was within the standard level for superior products derived from P. notoginseng. The content of notoginsenosides from all tissues except the main roots at fruit ripening stage, was 5% higher than the standard level specified in the Chinese Pharmacopoeia;(2) The treatment of As at 20 mg/kg led to an 3.5% - 183.9% increases in total notoginesenosides content in rhizome and main roots, respectively. Treatments with the highest As concentration at 260 mg/kg<sup> </sup>resulted in a significant decline in total notoginsenosides content, and lower enzymatic activity and gene expression levels of squalene synthetase;(3) Under As treatment conditions, the ratio of Rb1/Rg1 decreased but the ratio of (Rb1 + Rg1)/R1 increased in both rhizomes and main roots. Conclusively, this study demonstrated that low As concentration (20 - 80 mg/kg) treatments resulted in higher notoginsenoside content in P. notoginseng. However, treatments with high As concentrations had an adverse effect. The repression in the synthesis of notoginsenoside and interruption of the conversion process from propanaxadiol into propanaxatriol are responsible for more heterogeneous monomer mixtures and low notoginsenoside content. For plants treated with the highest As concentration of 260 mg/kg, both gene expression and enzymatic activities of squalene synthetase were greatly repressed thus leading to a significantly low saponin content in rhizome and main root tissues.展开更多
为了探明刺五加鲨烯合酶(SS)基因家族2成员对皂苷含量的作用机制,以actin为内参基因,利用real time PCR技术,分析刺五加不同生长发育时期、不同器官及茉莉酸甲酯(MeJA)处理对SS1、SS2基因表达及皂苷含量的影响。结果表明:刺五加SS基因...为了探明刺五加鲨烯合酶(SS)基因家族2成员对皂苷含量的作用机制,以actin为内参基因,利用real time PCR技术,分析刺五加不同生长发育时期、不同器官及茉莉酸甲酯(MeJA)处理对SS1、SS2基因表达及皂苷含量的影响。结果表明:刺五加SS基因家族的SS1和SS2在整个生长期和各器官中均有表达,且表达量差异显著(P<0.05),其中,在萌芽期两者的表达量差异最大。SS1在叶片、叶柄和根器官中的表达量显著高于SS2的表达量(P<0.05)。MeJA处理可显著提高SS1和SS2基因的表达量。刺五加SS1的表达量与皂苷含量间的相关系数低,未达显著水平。SS2的表达量与皂苷含量呈显著的正相关关系(P<0.01)。SS2表达量的高低决定了皂苷含量的高低,是刺五加中三萜皂苷生物合成中的关键酶。展开更多
目的研究黑老虎[Kadsura coccinea(Lem.)A. C. Smith]转录组特征,克隆三萜生物合成上游途径的关键酶基因角鲨烯合酶(KcSQS),为黑老虎资源利用奠定基础。方法对黑老虎不同部位进行转录组测序分析,根据筛选出的KcSQS候选基因序列设计引物...目的研究黑老虎[Kadsura coccinea(Lem.)A. C. Smith]转录组特征,克隆三萜生物合成上游途径的关键酶基因角鲨烯合酶(KcSQS),为黑老虎资源利用奠定基础。方法对黑老虎不同部位进行转录组测序分析,根据筛选出的KcSQS候选基因序列设计引物,利用PCR技术进行基因克隆,并借助生物学软件进行生物信息学分析。结果克隆得到一个KcSQS基因,包含全长1 227 bp的开放阅读框(ORF),编码408个氨基酸,预测其蛋白分子量为46.65 kD,定位于细胞质膜,含一段跨膜超螺旋结构。该基因在黑老虎叶片中表达量最高,与同科植物厚朴(Magnolia officinalis Rehd. et Wils.)角鲨烯合酶(MoSQS)蛋白序列相似性为76.77%,预测为角鲨烯合酶。结论该研究对黑老虎植物根、茎和叶进行转录组测序,成功克隆了角鲨烯合酶基因,并对其进行生物信息学分析,可为进一步研究黑老虎三萜类化合物的生物合成提供依据。展开更多
文摘As contamination is one of important factors to Panax notoginseng quality and safety. Saponin is one of important compounds with the medicinal values of P. notoginseng. The impact of soil As on production of saponin of P. notoginseng knew very little. This study was performed to determine content and heterogeneity of saponins from P. notoginseng and its mechanisms upon treatments with different concentration levels of As in soil. Plants of P. notoginseng were treated with arsenic [As (V)] at 0, 20, 80, 140, 20 and 260 mg/kg concentration levels which were supplied as sodium arsenate (Na<sub>3</sub>AsO<sub>4</sub>)<sub>.</sub> These experimental plants were grown in shade condition in a greenhouse. Plants were harvested at vigorous vegetative growth and fruit ripening stages, separately. Effects of As treatments on saponin content, and heterogeneity of monomers in the mixtures of notoginesenosides and ginsenosides, enzymatic activity and gene expression level of squalene synthetase were determined for rhizome and main root tissues. Results show that:(1) Of all the As treatments from the lowest to the highest concentration levels, the As content in both rhizome and main roots from As-treated plants was within the standard level for superior products derived from P. notoginseng. The content of notoginsenosides from all tissues except the main roots at fruit ripening stage, was 5% higher than the standard level specified in the Chinese Pharmacopoeia;(2) The treatment of As at 20 mg/kg led to an 3.5% - 183.9% increases in total notoginesenosides content in rhizome and main roots, respectively. Treatments with the highest As concentration at 260 mg/kg<sup> </sup>resulted in a significant decline in total notoginsenosides content, and lower enzymatic activity and gene expression levels of squalene synthetase;(3) Under As treatment conditions, the ratio of Rb1/Rg1 decreased but the ratio of (Rb1 + Rg1)/R1 increased in both rhizomes and main roots. Conclusively, this study demonstrated that low As concentration (20 - 80 mg/kg) treatments resulted in higher notoginsenoside content in P. notoginseng. However, treatments with high As concentrations had an adverse effect. The repression in the synthesis of notoginsenoside and interruption of the conversion process from propanaxadiol into propanaxatriol are responsible for more heterogeneous monomer mixtures and low notoginsenoside content. For plants treated with the highest As concentration of 260 mg/kg, both gene expression and enzymatic activities of squalene synthetase were greatly repressed thus leading to a significantly low saponin content in rhizome and main root tissues.
文摘为了探明刺五加鲨烯合酶(SS)基因家族2成员对皂苷含量的作用机制,以actin为内参基因,利用real time PCR技术,分析刺五加不同生长发育时期、不同器官及茉莉酸甲酯(MeJA)处理对SS1、SS2基因表达及皂苷含量的影响。结果表明:刺五加SS基因家族的SS1和SS2在整个生长期和各器官中均有表达,且表达量差异显著(P<0.05),其中,在萌芽期两者的表达量差异最大。SS1在叶片、叶柄和根器官中的表达量显著高于SS2的表达量(P<0.05)。MeJA处理可显著提高SS1和SS2基因的表达量。刺五加SS1的表达量与皂苷含量间的相关系数低,未达显著水平。SS2的表达量与皂苷含量呈显著的正相关关系(P<0.01)。SS2表达量的高低决定了皂苷含量的高低,是刺五加中三萜皂苷生物合成中的关键酶。
