Overexpression of a tea flavanone 3-hydroxylase gene confers tolerance to salt stress and Alternaria solani in transgenic tobacco
Overexpression of a tea flavanone 3-hydroxylase gene confers tolerance to salt stress and Alternaria solani in transgenic tobacco
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DOI：
10.1007/s11103-014-0203-z
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发表时间：
2014-08-01
影响因子：
5.1
通讯作者：
Yadav, Sudesh Kumar
中科院分区：
文献类型：
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作者：
Mahajan, Monika;Yadav, Sudesh Kumar
黄烷-3-醇是茶叶中主要的黄酮类化合物。已知这些在体外具有抗氧化剂和自由基清除特性。黄烷酮3-羟化酶是茶叶中黄烷醇类化合物积累途径中的重要酶。表达分析显示C.盐胁迫下的中华黄烷酮3-羟化酶（CsF 3 H）编码基因。本研究以烟草为材料，通过基因过量表达技术，对CsF 3 H的生物技术潜力进行了评价。Xanthi）。过量表达CsF 3 H cDNA可提高烟草中黄烷-3-醇类化合物的含量，并赋予烟草对盐胁迫和烟草早疫病菌（Alternaria solani）侵染的抗性。转基因烟草的初生根长度、侧根数、叶绿素含量、抗氧化酶表达量及其活性均有所增加。此外，他们表现出较少的丙二醛含量和电解质渗漏相比，对照烟草植物。此外，转基因植物产生更高程度的果胶甲酯化通过降低果胶甲酯酶（PME）在根和叶在非胁迫和盐胁迫条件下的活性。黄烷-3-醇对盐胁迫条件下果胶甲酯化的影响通过体外实验进一步验证，其中非转基因（野生）烟草幼苗在黄烷-3-醇、表儿茶素和表没食子儿茶素存在下暴露于盐胁迫。在体外暴露的幼苗表现出类似的趋势增加果胶甲酯化通过降低PME活性观察CsF 3 H转基因株系。总之，CsF 3 H的过表达提供了对盐胁迫和真菌A的耐受性。通过改善抗氧化系统和增强果胶甲酯化作用来提高转基因烟草对茄病菌的感染。
Flavan-3-ols are the major flavonoids present in tea (Camellia sinensis) leaves. These are known to have antioxidant and free radical scavenging properties in vitro. Flavanone 3-hydroxylase is considered to be an important enzyme of flavonoid pathway leading to accumulation of flavan-3-ols in tea. Expression analysis revealed the upregulation in transcript levels of C. sinensis flavanone 3-hydroxylase (CsF3H) encoding gene under salt stress. In this study, the biotechnological potential of CsF3H was evaluated by gene overexpression in tobacco (Nicotiana tabacum cv. Xanthi). Overexpression of CsF3H cDNA increased the content of flavan-3-ols in tobacco and conferred tolerance to salt stress and fungus Alternaria solani infection. Transgenic tobaccos were observed for increase in primary root length, number of lateral roots, chlorophyll content, antioxidant enzyme expression and their activities. Also, they showed lesser malondialdehyde content and electrolyte leakage compared to control tobacco plants. Further, transgenic plants produced higher degree of pectin methyl esterification via decreasing pectin methyl esterase (PME) activity in roots and leaves under unstressed and salt stressed conditions. The effect of flavan-3-ols on pectin methyl esterification under salt stressed conditions was further validated through in vitro experiments in which non-transgenic (wild) tobacco seedlings were exposed to salt stress in presence of flavan-3-ols, epicatechin and epigallocatechin. The in vitro exposed seedlings showed similar trend of increase in pectin methyl esterification through decreasing PME activity as observed in CsF3H transgenic lines. Taken together, overexpression of CsF3H provided tolerance to salt stress and fungus A. solani infection to transgenic tobacco through improved antioxidant system and enhanced pectin methyl esterification.