A Methionine Sulfoxide Reductase B Is Required for the Establishment of Astragalus sinicus-Mesorhizobium Symbiosis.
A Methionine Sulfoxide Reductase B Is Required for the Establishment of Astragalus sinicus-Mesorhizobium Symbiosis.
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黄芪-中生根瘤菌共生的建立需要甲硫氨酸亚硫酸还原酶 B。
DOI：
10.1093/pcp/pcaa085
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发表时间：
2020
影响因子：
4.9
通讯作者：
Li Youguo
中科院分区：
文献类型：
--
作者：
Si Zaiyong;Guan Ning;Zhou Yuan;Mei Lingli;Li Yixing;Li Youguo
甲硫氨酸亚砜还原酶B（MsrB）参与植物的氧化应激或防御反应。然而，很少有人知道它在豆科植物根瘤菌共生的作用。本研究从紫云英（Astragalus sinicus）中克隆了一个MsrB基因，并对其在共生中的功能进行了研究，AsMsrB基因在磷饥饿条件下被诱导表达，并在共生和非共生条件下表现出不同的表达模式。过氧化氢或甲基紫精处理提高了AsMsr在根和根瘤中的转录水平。亚细胞定位结果表明，AsMsRB定位于洋葱表皮细胞的细胞质中，并与根瘤菌共定位于根瘤中。与AsMsrB-RNAi毛状根的植物表现出显着的减少根瘤数，根瘤固氮酶活性和地上部分的鲜重，以及一个异常的根瘤和共生体的发展。对感染事件的统计分析表明，与对照相比，具有AsMsrB-RNAi毛状根的植株的根毛卷曲事件、感染丝和根瘤原基的数量显著减少。在感染初期，AsMsrB-RNAi根中过氧化氢含量增加，而AsMsrB-RNAi过表达根中过氧化氢含量降低。转录组分析表明，参与活性氧的产生和清除，防御和发病机制和早期发病的基因的表达的协同调节。此外，还通过双分子荧光互补鉴定并证实了与AsMsrB相互作用的候选蛋白。总而言之，我们的结果表明AsMsrB通过影响根和结节中的氧化还原动态平衡，在结节发育和共生固氮中发挥着重要作用。
Methionine sulfoxide reductase B (MsrB) is involved in oxidative stress or defense responses in plants. However, little is known about its role in legume–rhizobium symbiosis. In this study, anMsrBgene was identified fromAstragalus sinicusand its function in symbiosis was characterized.AsMsrBwas induced under phosphorus starvation and displayed different expression patterns under symbiotic and nonsymbiotic conditions. Hydrogen peroxide or methyl viologen treatment enhanced the transcript level ofAsMsrBin roots and nodules. Subcellular localization showed that AsMsrB was localized in the cytoplasm of onion epidermal cells and co-localized with rhizobia in nodules. Plants withAsMsrB-RNAi hairy roots exhibited significant decreases in nodule number, nodule nitrogenase activity and fresh weight of the aerial part, as well as an abnormal nodule and symbiosome development. Statistical analysis of infection events showed that plants withAsMsrB-RNAi hairy roots had significant decreases in the number of root hair curling events, infection threads and nodule primordia compared with the control. The content of hydrogen peroxide increased inAsMsrB-RNAi roots but decreased inAsMsrBoverexpression roots at the early stage of infection. The transcriptome analysis showed synergistic modulations of the expression of genes involved in reactive oxygen species generation and scavenging, defense and pathogenesis and early nodulation. In addition, a candidate protein interacting with AsMsrB was identified and confirmed by bimolecular fluorescence complementation. Taken together, our results indicate thatAsMsrBplays an essential role in nodule development and symbiotic nitrogen fixation by affecting the redox homeostasis in roots and nodules.