Changes in Sulforaphane and Selenocysteine Methyltransferase Transcript Levels in Broccoli Treated with Sodium Selenite
Changes in Sulforaphane and Selenocysteine Methyltransferase Transcript Levels in Broccoli Treated with Sodium Selenite
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DOI：
10.1007/s11105-015-0960-0
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发表时间：
2016-08-01
影响因子：
2.1
通讯作者：
Xiao, W. J.
中科院分区：
文献类型：
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作者：
Huang, K.;Lin, J. C.;Xiao, W. J.
西兰花（Brassica oleracea L. var. italica planck）因其营养成分而受到高度重视，这归因于含硫化合物萝卜硫素和富硒能力。萝卜硫素的合成可能受到 Se/S 代谢的影响，因为硫酸盐和硒酸盐在植物中具有相同的初始吸收途径。硒代半胱氨酸甲基转移酶（SMT）在 Se/S 代谢系统中发挥着关键作用。在本工作中，我们分析了在正常和硒胁迫条件下过表达和RNAi敲低SMT的条件下转基因西兰花中SMT的表达水平和萝卜硫素含量。过表达株系中SMT的相对表达量比未转化对照高13.93%。有趣的是，硒处理后过表达株系的萝卜硫素含量降低了14.09%，而空载体(pCAMBIA1301)转化和未转化植株的萝卜硫素含量分别比未硒处理的植株低59.04和66.56%。在SMT-RNAi系中，SMT相对表达值比未转化的低15.60%，硒处理后我们无法检测到萝卜硫素。这些结果表明，SMT 在富硒环境中萝卜硫素的合成中发挥着关键作用。具体来说，SMT的过度表达减少了硒对萝卜硫素合成的负面影响，而通过RNAi敲低SMT则增强了负面影响。
Broccoli (Brassica oleracea L. var. italica planck) has been highly valued because of its nutrient content, which has been attributed to both sulforaphane, a sulfur-containing compound, and selenium enrichment ability. The sulforaphane synthesis may be affected by Se/S metabolism because sulfate and selenate share the same initial pathway for uptake in plants. Selenocysteine methyltransferase (SMT) plays a critical role in the Se/S metabolism system. In the present work, we analyzed the SMT expression level and sulforaphane content in transgenic broccoli under the conditions of overexpression and RNAi knockdown of SMT under normal and selenium-stressed conditions. The relative expression value of SMT in the overexpression line is 13.93 % higher than that in the untransformed control. Interestingly, the sulforaphane content of the overexpression line was 14.09 % lower after selenium treatment, while that of the empty vector (pCAMBIA1301) transformed and untransformed plants was 59.04 and 66.56 % lower than that of the non-seleniumtreated, respectively. In the SMT-RNAi line, which has a relative expression value for SMT 15.60 % lower than that of the untransformed, we cannot detect sulforaphane after selenium treatment. These results showed that SMT plays a key role in sulforaphane synthesis in a selenium-rich environment. Specifically, overexpression of SMT decreases the negative effect of selenium on sulforaphane synthesis, while knockdown of SMT by RNAi enhances the negative effect.