Abdollahi Mandoulakani Babak, Eyvazpour Elham, Ghadimzadeh Morteza
Department of Plant Breeding and Biotechnology, Faculty of Agriculture, Urmia University, Urmia, Iran; Department of Agricultural Biotechnology, Institute of Biotechnology, Urmia University, Urmia, Iran.
Department of Plant Breeding and Biotechnology, Faculty of Agriculture, Urmia University, Urmia, Iran.
Phytochemistry. 2017 Jul;139:1-7. doi: 10.1016/j.phytochem.2017.03.006. Epub 2017 Mar 30.
Basil (Ocimum basilicum L.), a medicinal plant of the Lamiaceae family, is used in traditional medicine; its essential oil is a rich source of phenylpropanoids. Methylchavicol and methyleugenol are the most important constituents of basil essential oil. Drought stress is proposed to enhance the essential oil composition and expression levels of the genes involved in its biosynthesis. In the current investigation, an experiment based on a completely randomized design (CRD) with three replications was conducted in the greenhouse to study the effect of drought stress on the expression level of four genes involved in the phenylpropanoid biosynthesis pathway in O. basilicum c.v. Keshkeni luvelou. The genes studied were chavicol O-methyl transferase (CVOMT), eugenol O-methyl transferase (EOMT), cinnamate 4-hydroxylase (C4H), 4-coumarate coA ligase (4CL), and cinnamyl alcohol dehydrogenase (CAD). The effect of drought stress on the essential oil compounds and their relationship with the expression levels of the studied genes were also investigated. Plants were subjected to levels of 100%, 75%, and 50% of field capacity (FC) at the 6-8 leaf stage. Essential oil compounds were identified by gas chromatography/mass spectrometry (GC-MS) at flowering stage and the levels of gene expression were determind by real time PCR in plant leaves at the same stage. Results showed that drought stress increased the amount of methylchavicol, methyleugenol, β-Myrcene and α-bergamotene. The maximum amount of these compounds was observed at 50% FC. Real-time PCR analysis revealed that severe drought stress (50% FC) increased the expression level of CVOMT and EOMT by about 6.46 and 46.33 times, respectively, whereas those of CAD relatively remained unchanged. The expression level of 4CL and C4H reduced under drought stress conditions. Our results also demonstrated that changes in the expression levels of CVOMT and EOMT are significantly correlated with methylchavicol (r = 0.94, P ≤ 0.05) and methyleugenol (r = 0.98, P ≤ 0.05) content. Thus, drought stress probably increases the methylchavicol and methyleugenol content, in part, through increasing the expression levels of CVOMT and EOMT.
罗勒（Ocimum basilicum L.）是唇形科的一种药用植物，用于传统医学；其精油富含苯丙素类化合物。甲基胡椒酚和甲基丁香酚是罗勒精油的最重要成分。干旱胁迫被认为可增强精油成分及其生物合成相关基因的表达水平。在当前研究中，在温室中进行了一项基于完全随机设计（CRD）且有三次重复的实验，以研究干旱胁迫对罗勒品种Keshkeni luvelou中参与苯丙素生物合成途径的四个基因表达水平的影响。所研究的基因有胡椒酚O - 甲基转移酶（CVOMT）、丁香酚O - 甲基转移酶（EOMT）、肉桂酸4 - 羟化酶（C4H）、4 - 香豆酸辅酶A连接酶（4CL）和肉桂醇脱氢酶（CAD）。还研究了干旱胁迫对精油成分的影响及其与所研究基因表达水平的关系。在6 - 8叶期，使植株遭受田间持水量（FC）100%、75%和50%的水平。在开花期通过气相色谱/质谱联用（GC - MS）鉴定精油成分，并在同一时期通过实时荧光定量PCR测定植株叶片中的基因表达水平。结果表明，干旱胁迫增加了甲基胡椒酚、甲基丁香酚、β - 月桂烯和α - 佛手柑油烯的含量。在50% FC时观察到这些化合物的含量最高。实时荧光定量PCR分析表明，严重干旱胁迫（50% FC）使CVOMT和EOMT的表达水平分别提高了约6.46倍和46.33倍，而CAD的表达水平相对保持不变。在干旱胁迫条件下，4CL和C4H的表达水平降低。我们的结果还表明，CVOMT和EOMT表达水平的变化与甲基胡椒酚（r = 0.94，P≤0.05）和甲基丁香酚（r = 0.98，P≤0.05）含量显著相关。因此，干旱胁迫可能部分通过提高CVOMT和EOMT的表达水平来增加甲基胡椒酚和甲基丁香酚的含量。
