School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
Mol Plant Microbe Interact. 2018 Mar;31(3):323-333. doi: 10.1094/MPMI-08-17-0208-R. Epub 2018 Jan 12.
Plant hormone salicylic acid (SA) plays critical roles in defense signaling against biotrophic pathogens. Pathogen inoculation leads to SA accumulation in plants. SA activates a transactivator protein NPR1, which, in turn, transcriptionally activates many defense response genes. Reports also suggest the presence of NPR1-independent pathways for SA signaling in Arabidopsis. Here, we report the characterization of a zinc-finger protein-coding gene AtOZF1 that positively influences NPR1-independent SA signaling. Mutants of AtOZF1 are compromised, whereas AtOZF1-overexpressing plants are hyperactive for defense against virulent and avirulent pathogens. AtOZF1 expression is SA-inducible. AtOZF1 function is not required for pathogenesis-associated biosynthesis and accumulation of SA. However, it is required for SA responsiveness. By generating atozf1npr1 double mutant, we show that contributions of these two genes are additive in terms of defense. We identified AtOZF1-interacting proteins by a yeast-two-hybrid screening of an Arabidopsis cDNA library. VDAC2 and NHL3 are two AtOZF1-interacting proteins, which are positive regulators of basal defense. AtOZF1 interacts with NHL3 and VDAC2 in plasma membrane and mitochondria, respectively. Our results demonstrate that AtOZF1 coordinates multiple steps of plant-pathogen interaction.
植物激素水杨酸（SA）在对生物营养病原体的防御信号中起着关键作用。病原体接种会导致植物中 SA 的积累。SA 激活转录激活蛋白 NPR1，进而转录激活许多防御反应基因。报告还表明，拟南芥中存在 NPR1 非依赖性的 SA 信号通路。在这里，我们报道了一个锌指蛋白编码基因 AtOZF1 的特征，该基因正向影响 NPR1 非依赖性的 SA 信号。AtOZF1 突变体受到损害，而 AtOZF1 过表达植物对毒性和非毒性病原体的防御表现出过度活跃。AtOZF1 表达受 SA 诱导。AtOZF1 功能对于与发病相关的 SA 生物合成和积累不是必需的。然而，它是 SA 反应所必需的。通过生成 atozf1npr1 双突变体，我们表明这两个基因在防御方面的贡献是累加的。我们通过对拟南芥 cDNA 文库进行酵母双杂交筛选，鉴定了 AtOZF1 相互作用蛋白。VDAC2 和 NHL3 是两个 AtOZF1 相互作用蛋白，它们是基础防御的正调节剂。AtOZF1 分别与 NHL3 和 VDAC2 在质膜和线粒体中相互作用。我们的结果表明，AtOZF1 协调了植物-病原体相互作用的多个步骤。
