Laboratoire de Biochimie & Physiologie Moléculaire des Plantes, UMR Université Montpellier 2, CNRS, INRA, Montpellier SupAgro, 2 place Viala, F-34060 Montpellier Cedex 02, France.
New Phytol. 2011 Oct;192(1):140-150. doi: 10.1111/j.1469-8137.2011.03792.x. Epub 2011 Jun 16.
• Apart from their antifungal role, plant defensins have recently been shown to be involved in abiotic stress tolerance or in inhibition of root growth when added in plant culture medium. We studied the subcellular localization of these proteins, which may account for these different roles. • Stable and transient expression of AhPDF1.1::GFP (green fluorescent protein) fusion proteins were analysed in yeast and plants. Functional tests established that the GFP tag did not alter the action of the defensin. Subcellular localization of AhPDF1.1 was characterized: by imaging AhPDF1.1::GFP together with organelle markers; and by immunolabelling AhPDF1.1 in Arabidopsis halleri and Arabidopsis thaliana leaves using a polyclonal serum. • All our independent approaches demonstrated that AhPDF1.1 is retained in intracellular compartments on the way to the lytic vacuole, instead of being addressed to the apoplasm. • These findings challenge the commonly accepted idea of secretion of defensins. The subcellular localization highlighted in this study could partly explain the dual role of plant defensins on plant cells and is of major importance to unravel the mechanisms of action of these proteins at the cellular level.
除了抗真菌作用外，植物防御素最近还被证明在添加到植物培养基中时参与非生物胁迫耐受或抑制根生长。我们研究了这些蛋白质的亚细胞定位，这可能解释了它们的不同作用。
在酵母和植物中分析了 AhPDF1.1::GFP（绿色荧光蛋白）融合蛋白的稳定和瞬时表达。功能测试证实 GFP 标签不会改变防御素的作用。AhPDF1.1 的亚细胞定位特征为：通过与细胞器标记物共成像 AhPDF1.1::GFP；并使用多克隆血清在拟南芥和拟南芥叶片中对 AhPDF1.1 进行免疫标记。
我们所有的独立方法都证明，AhPDF1.1 在向溶酶体的运输过程中被保留在细胞内隔室中，而不是被递送到质外体。
这些发现挑战了防御素分泌的普遍观点。本研究中突出的亚细胞定位可以部分解释植物防御素对植物细胞的双重作用，对于在细胞水平上阐明这些蛋白质的作用机制具有重要意义。
