Arabidopsis mutants resistant to S(+)-β-methyl-α, β-diaminopropionic acid, a cycad-derived glutamate receptor agonist
Arabidopsis mutants resistant to S(+)-β-methyl-α, β-diaminopropionic acid, a cycad-derived glutamate receptor agonist
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DOI：
10.1104/pp.124.4.1615
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发表时间：
2000-12-01
期刊：
影响因子：
7.4
通讯作者：
Coruzzi, GM
中科院分区：
文献类型：
--
作者：
Brenner, ED;Martinez-Barboza, N;Coruzzi, GM
嗜离子性谷氨酸受体（iGluRs）是一种配体门控离子通道，是哺乳动物大脑中主要的神经受体。在拟南芥中发现了与动物iGluRs序列高度相似的基因。为了了解拟南芥谷氨酸受体样（AK；LR）基因在植物中的作用，我们采用药理学方法研究了苏铁衍生的iGluR激动剂BMAA [S(+)- β -甲基- α， β -二氨基丙酸]对拟南芥形态发生的影响。在拟南芥幼苗发育早期，施用BMAA可使下胚轴伸长增加2 ~ 3倍，并抑制子叶开放。BMAA对下胚轴伸长的影响不明显。此外，BMAA对拟南芥早期形态发生的影响可以通过同时应用动物体内的天然iGluR激动剂谷氨酸来逆转。为了确定BMAA在拟南芥中的作用靶点，设计了一种遗传筛选方法来分离具有BMAA不敏感形态（bim）的拟南芥突变体。当在BMAA光照下生长时，与野生型相比，他突变体的下胚轴较短。根据在没有BMAA的黑暗环境中生长时的形态，将其突变体分为三类。i类突变体具有正常的黄化形态，类似于野生型植物。ii类突变体在黑暗中生长时，下胚轴较短，子叶闭合。iii类突变体在黑暗中生长时具有短的下胚轴和开放的子叶，类似于先前表征的组成型光形态突变体（cop, det， Jus和shy）。对bim突变体的进一步分析将有助于确定植物源性iGluR激动剂是否靶向植物中的谷氨酸受体信号通路。
Ionotropic glutamate receptors (iGluRs) are ligand-gated ion channels that are the predominant neuroreceptors in the mammalian brain. Genes with high sequence similarity to animal iGluRs have been identified in Arabidopsis. To understand the role of Arabidopsis glutamate receptor-like (AK;LR) genes in plants, we have taken a pharmacological approach by examining the effects of BMAA [S(+)-beta -methyl-alpha, beta -diaminopropionic acid], a cycad-derived iGluR agonist, on Arabidopsis morphogenesis. When applied to Arabidopsis seedlings, BMAA caused a 2- to 3-fold increase in hypocotyl elongation and inhibited cotyledon opening during early seedling development. The effect of BMAA on hypocotyl elongation is light specific. Furthermore, BMAA effects on early morphogenesis of Arabidopsis can be reversed by the simultaneous application of glutamate, the native iGluR agonist in animals. To determine the targets of BMAA action in Arabidopsis, a genetic screen was devised to isolate Arabidopsis mutants with a BMAA insensitive morphology (bim). When grown in the light on BMAA, bim mutants exhibited short hypocotyls compared with wild type. bim mutants were grouped into three classes based on their morphology when grown in the dark in the absence of BMAA. Class-I bim mutants have a normal, etiolated morphology, similar to wild-type plants. Class-II bim mutants have shorter hypocotyls and closed cotyledons when grown in the dark. Class-III bim mutants have short hypocotyls and open cotyledons when grown in the dark, resembling the previously characterized constitutively photomorphogenic mutants (cop, det, Jus, and shy). Further analysis of the bim mutants should help define whether plant-derived iGluR agonists target glutamate receptor signaling pathways in plants.