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为探究甜叶菊叶片中甜菊糖苷积累与其合成途径上关键基因表达的关系,本研究分别检测了鑫丰3号苗期不同冠层和3个不同品种甜叶菊(守田3号、江甜3号、谱星1号)收获期混合叶片样品中多种糖苷的含量,同时定量检测对应样品中甜菊糖苷合成关键基因的表达水平。结果显示,总糖苷在鑫丰3号顶叶中最高,底叶中最低,而多数检测基因(6/8)表达水平也在顶叶最高底叶中最低;单一糖苷甜菊苷在顶叶中积累最高,而其催化酶编码基因Sr UGT74G1表达也在顶叶中最高;莱鲍迪苷A则在底叶中积累最多,其催化酶编码基因Sr UGT76G1表达水平也在底叶中表达最高。3个品种相比,总糖苷和莱鲍迪苷A的积累在江甜3号中最高,谱星1号中最低;甜菊苷的积累在守田3号中最高,江甜3号中最低,但基因表达水平与糖苷积累趋势一致的类似结果并未在不同品种间出现。由此可知,甜菊糖苷合成基因的表达水平可以影响总糖苷的积累,且在同一甜叶菊品种中单一糖苷合成调控基因的表达水平可以反映其调控的单糖苷的积累量。
In order to explore the relationship between stevioside accumulation and expression of key genes in the synthesis pathway of Stevia rebaudiana leaves, we investigated the effects of Xinfeng No.3 seedling stage and three different varieties of stevia rebaudiana (Shiantan 3, Jiangtian 3, Spectrum Star No. 1) in the mixed leaf samples during harvest, and quantitatively detected the expression level of the key genes involved in the synthesis of stevioside in the corresponding samples. The results showed that the total glycoside was the highest in Xinfeng 3 parietal lobe and lowest in the bottom lobe, while the expression level of most of the detected genes (6/8) was also the lowest in the lobe of the parietal lobe. The single glycoside stevioside accumulated in the parietal lobe While the expression of Sr UGT74G1 was the highest in the parietal lobe. Rebaudioside A accumulated the most in the lobe and the expression level of Sr UGT76G1 was the highest in the bottom leaves. The accumulation of total glycosides and rebaudioside A was the highest in Jiangtian 3 and the lowest in Spectrum 1 among the three cultivars. The accumulation of stevioside was highest in Shaotian 3 and lowest in Jiangtian 3 Similar results of consistent gene expression levels and glycosidic accumulation have not occurred among different breeds. It can be seen that the expression level of the gene for the synthesis of stevioside can affect the accumulation of the total glycosides, and the expression level of the single glycosynthase regulatory gene in the same stevia cultivar can reflect the accumulation of monosaccharides regulated by the same.