Dek Mohd Sabri Pak, Padmanabhan Priya, Sherif Sherif, Subramanian Jayasankar, Paliyath And Gopinadhan
Department of Plant Agriculture, University of Guelph, Guelph, ON, N1G 2W1, Canada.
Department of Food Science, Faculty of Food Science and Technology, Universiti Putra Malaysia, 43400 Serdang, Malaysia.
Int J Mol Sci. 2017 Jul 15;18(7):1533. doi: 10.3390/ijms18071533.
Phosphatidylinositol 3-kinase (PI3K) is a key enzyme that phosphorylates phosphatidylinositol at 3'-hydroxyl position of the inositol head group initiating the generation of several phosphorylated phosphatidylinositols, collectively referred to as phosphoinositides. The function of PI3K in plant senescence and ethylene signal transduction process was studied by expression of PI3K in transgenic , and delineating its effect on flower senescence. Detached flowers of transgenic tobacco plants with overexpressed - (OX) displayed accelerated senescence and reduced longevity, when compared to the flowers of wild type plants. Flowers from PI3K-overexpressing plants showed enhanced ethylene production and upregulated expression of 1-aminocyclopropane-1-carboxylic acid oxidase 1 (). Real time polymerase chain reaction (PCR) analysis showed that was expressed at a higher level in OX flowers than in the control. Seedlings of OX-lines also demonstrated a triple response phenotype with characteristic exaggerated apical hook, shorter hypocotyls and increased sensitivity to 1-aminocyclopropane-1-carboxylate than the control wild type seedlings. In floral tissue from OX-lines, phosphatidylinositol 3-kinase green fluorescent protein (PI3K-GFP) chimera protein was localized primarily in stomata, potentially in cytoplasm and membrane adjacent to stomatal pores in the guard cells. Immunoblot analysis of PI3K expression in OX lines demonstrated increased protein level compared to the control. Results of the present study suggest that PI3K plays a crucial role in senescence by enhancing ethylene biosynthesis and signaling.
磷脂酰肌醇3激酶（PI3K）是一种关键酶，它能使肌醇头部基团的3'-羟基位置的磷脂酰肌醇磷酸化，从而引发几种磷酸化磷脂酰肌醇的生成，这些磷脂酰肌醇统称为磷酸肌醇。通过在转基因植物中表达PI3K并描述其对花朵衰老的影响，研究了PI3K在植物衰老和乙烯信号转导过程中的作用。与野生型植物的花朵相比，过表达PI3K的转基因烟草植株的离体花朵表现出加速衰老和寿命缩短。来自PI3K过表达植物的花朵显示乙烯产量增加，1-氨基环丙烷-1-羧酸氧化酶1（ACO1）的表达上调。实时聚合酶链反应（PCR）分析表明，ACO1在过表达植株的花朵中的表达水平高于对照。过表达株系的幼苗也表现出三重反应表型，其特征是顶端弯钩夸张、下胚轴较短，并且比对照野生型幼苗对1-氨基环丙烷-1-羧酸盐的敏感性增加。在过表达株系的花组织中，磷脂酰肌醇3激酶绿色荧光蛋白（PI3K-GFP）嵌合蛋白主要定位于气孔，可能位于保卫细胞中气孔孔附近的细胞质和细胞膜中。对过表达株系中PI3K表达的免疫印迹分析表明，与对照相比，蛋白水平增加。本研究结果表明，PI3K通过增强乙烯生物合成和信号传导在衰老中起关键作用。
