Guangdong Province Key Laboratory of Microbial Signals and Disease Control, College of Plant Protection, South China Agricultural University, Guangzhou 510642, China.
College of Marine and Biotechnology, Guangxi Minzu University, Nanning 530008, China.
Int J Mol Sci. 2023 Feb 24;24(5):4494. doi: 10.3390/ijms24054494.
Phytoplasmas are uncultivable, phloem-limited, phytopathogenic bacteria that represent a major threat to agriculture worldwide. Phytoplasma membrane proteins are in direct contact with hosts and presumably play a crucial role in phytoplasma spread within the plant as well as by the insect vector. Three highly abundant types of immunodominant membrane proteins (IDP) have been identified within the phytoplasmas: immunodominant membrane protein (Imp), immunodominant membrane protein A (IdpA), and antigenic membrane protein (Amp). Although recent results indicate that Amp is involved in host specificity by interacting with host proteins such as actin, little is known about the pathogenicity of IDP in plants. In this study, we identified an antigenic membrane protein (Amp) of rice orange leaf phytoplasma (ROLP), which interacts with the actin of its vector. In addition, we generated Amp-transgenic lines of rice and expressed Amp in tobacco leaves by the potato virus X (PVX) expression system. Our results showed that the Amp of ROLP can induce the accumulation of ROLP and PVX in rice and tobacco plants, respectively. Although several studies have reported interactions between major phytoplasma antigenic membrane protein (Amp) and insect vector proteins, this example demonstrates that Amp protein can not only interact with the actin protein of its insect vector but can also directly inhibit host defense responses to promote the infection. The function of ROLP Amp provides new insights into the phytoplasma-host interaction.
植原体是无法培养的、局限在韧皮部的、植物病原细菌，它们对全球农业构成了重大威胁。植原体膜蛋白与宿主直接接触，推测在植原体在植物体内以及通过昆虫介体传播中发挥着关键作用。在植原体中已经鉴定出三种高度丰富的免疫显性膜蛋白（IDP）：免疫显性膜蛋白（Imp）、免疫显性膜蛋白 A（IdpA）和抗原性膜蛋白（Amp）。尽管最近的研究结果表明 Amp 通过与肌动蛋白等宿主蛋白相互作用参与了宿主特异性，但对于 IDP 在植物中的致病性知之甚少。在这项研究中，我们鉴定了水稻橙叶植原体（ROLP）的一种抗原性膜蛋白（Amp），它与载体的肌动蛋白相互作用。此外，我们通过马铃薯 X 病毒（PVX）表达系统在水稻中生成了 Amp 转基因系，并在烟草叶片中表达了 Amp。我们的结果表明，ROLP 的 Amp 可以分别诱导 ROLP 和 PVX 在水稻和烟草植物中的积累。尽管有几项研究报道了主要植原体抗原性膜蛋白（Amp）与昆虫介体蛋白之间的相互作用，但这个例子表明 Amp 蛋白不仅可以与昆虫载体的肌动蛋白相互作用，还可以直接抑制宿主防御反应以促进感染。ROLP Amp 的功能为植原体-宿主相互作用提供了新的见解。
