Elucidating the Role of Transport Processes in Leaf Glucosinolate Distribution
Elucidating the Role of Transport Processes in Leaf Glucosinolate Distribution
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DOI：
10.1104/pp.114.246249
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发表时间：
2014-11-01
期刊：
影响因子：
7.4
通讯作者：
Halkier, Barbara Ann
中科院分区：
文献类型：
--
作者：
Madsen, Svend Roesen;Olsen, Carl Erik;Halkier, Barbara Ann
在拟南芥（Arabidopsis thaliana）中，保护其叶片免受食草动物侵害的策略是沿着中脉和边缘积累芥子油苷。虽然人们通常认为芥子油苷是沿着拟南芥叶片中的脉管系统合成的，从而表明边缘积累是通过运输建立的，但对这些运输过程知之甚少。在这里，我们表明，通过叶质外体流体分析和硫代葡萄糖苷喂养实验，两个硫代葡萄糖苷转运蛋白，GTR 1和GTR 2，在拟南芥中的硫代葡萄糖苷的长距离运输必不可少的，也发挥了关键作用，在一个成熟的叶片内有效地进口质外体本地化的硫代葡萄糖苷到适当的细胞中的硫代葡萄糖苷分配。根木质部汁液中硫代葡萄糖苷的检测明确表明，这种运输途径参与根到地上部的硫代葡萄糖苷分配。详细的叶片解剖表明，在GTR 1和GTR 2的运输活动的情况下，芥子油苷积累主要在叶缘和叶尖。此外，我们表明，硫代葡萄糖苷积累在叶下表皮中的GTR独立的方式。基于我们的研究结果，我们提出了一个模型，硫代葡萄糖苷积累在叶缘和表皮，其中包括通过胞间连丝共质运动，加上这些外围细胞层中的推定的液泡硫代葡萄糖苷进口商的活动。
In Arabidopsis (Arabidopsis thaliana), a strategy to defend its leaves against herbivores is to accumulate glucosinolates along the midrib and at the margin. Although it is generally assumed that glucosinolates are synthesized along the vasculature in an Arabidopsis leaf, thereby suggesting that the margin accumulation is established through transport, little is known about these transport processes. Here, we show through leaf apoplastic fluid analysis and glucosinolate feeding experiments that two glucosinolate transporters, GTR1 and GTR2, essential for long-distance transport of glucosinolates in Arabidopsis, also play key roles in glucosinolate allocation within a mature leaf by effectively importing apoplastically localized glucosinolates into appropriate cells. Detection of glucosinolates in root xylem sap unambiguously shows that this transport route is involved in root-to-shoot glucosinolate allocation. Detailed leaf dissections show that in the absence of GTR1 and GTR2 transport activity, glucosinolates accumulate predominantly in leaf margins and leaf tips. Furthermore, we show that glucosinolates accumulate in the leaf abaxial epidermis in a GTR-independent manner. Based on our results, we propose a model for how glucosinolates accumulate in the leaf margin and epidermis, which includes symplasmic movement through plasmodesmata, coupled with the activity of putative vacuolar glucosinolate importers in these peripheral cell layers.