Functional Characterization of 4′OMT and 7OMT Genes in BIA Biosynthesis
Functional Characterization of 4′OMT and 7OMT Genes in BIA Biosynthesis
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DOI：
10.3389/fpls.2016.00098
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发表时间：
2016-02-16
影响因子：
5.6
通讯作者：
Unver, Turgay
中科院分区：
文献类型：
--
作者：
Gurkok, Tugba;Ozhuner, Esma;Unver, Turgay
生物碱是一类广泛存在于植物体内的次生代谢产物。罂粟（罂粟（Papaver somniferum L.），是吗啡烷生物碱的唯一商业来源，自古以来一直被用作药用植物。它产生苄基异喹啉生物碱（BIA），包括麻醉镇痛剂吗啡，肌肉松弛剂罂粟碱和抗癌剂诺斯卡品。尽管BIA在许多生物学机制中起着关键作用，但其生物合成步骤和相关基因仍有待揭示。在这项研究中，3-羟基-N-甲基乌药碱4 '-甲基转移酶（4' OMT）和牛心果碱7-O-甲基转移酶（7 OMT）基因的表达进行了操作，以功能上表征其在BIA生物合成中的作用。相应地在叶、茎和蒴果组织中进行生物碱积累的测量。抑制4 'OMT表达导致茎组织中总生物碱含量降低，而蒴果中总生物碱含量显著诱导。7 OMT基因的沉默也导致抑制茎中的总生物碱含量。另一方面，4 'OMT和7 OMT的过表达导致茎中吗啡积累增加，但抑制了蒴果中的吗啡量。此外，在几个BIA合成基因（CNMT. TYDC，6OMT，SAT。COR，4'OMT。和7 OMT）。在沉默和过表达应用后，鉴定了这些基因的组织特异性效应。4 'OMT和7 OMT基因的操作引起BIA包括吗啡和那可丁在囊和茎组织中的分化积累。
Alkaloids are diverse group of secondary metabolites generally found in plants. Opium poppy (Papaver somniferum L.), the only commercial source of morphinan alkaloids, has been used as a medicinal plant since ancient times. It produces benzylisoquinoline alkaloids (BIA) including the narcotic analgesic morphine, the muscle relaxant papaverine, and the anti-cancer agent noscapine. Though BIAs play crucial roles in many biological mechanisms their steps in biosynthesis and the responsible genes remain to be revealed. In this study, expressions of 3-hydroxy-N-methylcoclaurine 4'-methyltransferase (4'OMT) and reticuline 7-O-methyltransferase (7OMT) genes were subjected to manipulation to functionally characterize their roles in BIA biosynthesis. Measurements of alkaloid accumulation were performed in leaf, stem, and capsule tissues accordingly. Suppression of 4'OMT expression caused reduction in the total alkaloid content in stem tissue whereas total alkaloid content was significantly induced in the capsule. Silencing of the 7OMT gene also caused repression in total alkaloid content in the stem. On the other hand, over-expression of 4'OMT and 7OMT resulted in higher morphine accumulation in the stem but suppressed amount in the capsule. Moreover, differential expression in several BIA synthesis genes (CNMT. TYDC, 6OMT, SAT. COR, 4'OMT. and 7OMT) were observed upon manipulation of 4'OMT and 7OMT expression. Upon silencing and overexpression applications, tissue specific effects of these genes were identified. Manipulation of 4'OMT and 7OMT genes caused differentiated accumulation of BIAs including morphine and noscapine in capsule and stem tissues.