School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong, China.
Plant Physiol. 2011 Aug;156(4):2069-81. doi: 10.1104/pp.111.176933. Epub 2011 Jun 13.
ACBP3 is one of six Arabidopsis (Arabidopsis thaliana) genes, designated ACBP1 to ACBP6, that encode acyl-coenzyme A (CoA)-binding proteins (ACBPs). These ACBPs bind long-chain acyl-CoA esters and phospholipids and are involved in diverse cellular functions, including acyl-CoA homeostasis, development, and stress tolerance. Recombinant ACBP3 binds polyunsaturated acyl-CoA esters and phospholipids in vitro. Here, we show that ACBP3 plays a role in the plant defense response to the bacterial pathogen Pseudomonas syringae pv tomato DC3000. ACBP3 mRNA was up-regulated upon pathogen infection and treatments using pathogen elicitors and defense-related phytohormones. Transgenic Arabidopsis ACBP3 overexpressors (ACBP3-OEs) showed constitutive expression of pathogenesis-related genes (PR1, PR2, and PR5), cell death, and hydrogen peroxide accumulation in leaves. Consequently, ACBP3-OEs displayed enhanced resistance to the bacterial pathogen P. syringae DC3000. In contrast, the acbp3 T-DNA insertional mutant was more susceptible and exhibited lower PR gene transcript levels upon infection. Using the ACBP3 OE-1 line in combination with nonexpressor of PR genes1 (npr1-5) or coronatine-insensitive1 (coi1-2), we concluded that the enhanced PR gene expression and P. syringae DC3000 resistance in the ACBP3-OEs are dependent on the NPR1-mediated, but not the COI1-mediated, signaling pathway. Given that ACBP3-OEs showed greater susceptibility to infection by the necrotrophic fungus Botrytis cinerea while the acbp3 mutant was less susceptible, we suggest that ACBP3 plays a role in the plant defense response against biotrophic pathogens that is distinct from necrotrophic pathogens. ACBP3 function in plant defense was supported further by bioinformatics data showing up-regulation of many biotic and abiotic stress-related genes in ACBP3 OE-1 in comparison with the wild type.
ACBP3 是拟南芥（Arabidopsis thaliana）6 个基因之一，分别命名为 ACBP1 到 ACBP6，这些基因编码酰基辅酶 A（CoA）结合蛋白（ACBPs）。这些 ACBPs 结合长链酰基辅酶 A 酯和磷脂，并参与多种细胞功能，包括酰基辅酶 A 稳态、发育和应激耐受。重组 ACBP3 在体外结合多不饱和酰基辅酶 A 酯和磷脂。在这里，我们表明 ACBP3 在植物对细菌病原体丁香假单胞菌 pv 番茄 DC3000 的防御反应中发挥作用。病原体感染和使用病原体激发子和防御相关植物激素处理后，ACBP3 mRNA 上调。拟南芥 ACBP3 过表达转基因（ACBP3-OE）表现出病程相关基因（PR1、PR2 和 PR5）的组成型表达、细胞死亡和叶片中过氧化氢的积累。因此，ACBP3-OE 对细菌病原体丁香假单胞菌 DC3000 表现出增强的抗性。相比之下，acbp3 T-DNA 插入突变体在感染时更敏感，PR 基因转录水平更低。使用 ACBP3 OE-1 系与非表达病程相关基因 1（npr1-5）或冠菌素不敏感 1（coi1-2）组合，我们得出结论，ACBP3-OE 中增强的 PR 基因表达和对丁香假单胞菌 DC3000 的抗性依赖于 NPR1 介导的信号通路，但不依赖于 COI1 介导的信号通路。鉴于 ACBP3-OE 对坏死真菌 Botrytis cinerea 的感染表现出更高的敏感性，而 acbp3 突变体的敏感性较低，我们认为 ACBP3 在植物对生物病原体的防御反应中发挥作用，与坏死病原体不同。生物信息学数据进一步支持了 ACBP3 在植物防御中的功能，与野生型相比，ACBP3 OE-1 中许多生物和非生物胁迫相关基因上调。
