MALDI mass spectrometry-assisted molecular imaging of metabolites during nitrogen fixation in the Medicago truncatula-Sinorhizobium meliloti symbiosis
MALDI mass spectrometry-assisted molecular imaging of metabolites during nitrogen fixation in the Medicago truncatula-Sinorhizobium meliloti symbiosis
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DOI：
10.1111/tpj.12191
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发表时间：
2013-07-01
期刊：
影响因子：
7.2
通讯作者：
Li, Lingjun
中科院分区：
文献类型：
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作者：
Ye, Hui;Gemperline, Erin;Li, Lingjun
豆科植物和固氮根瘤菌之间的共生关系在形成称为根瘤的特殊器官时达到高潮，根瘤菌在根瘤中固定大气中的氮并将其转移到植物中。有效的生物固氮依赖于双方产生和交换的代谢物。由于两种共生伙伴的遗传信息的可用性，截根紫花苜蓿-中华根瘤菌的关联是解剖这种固氮共生关系的一个极好的模型。本研究采用基质辅助激光解吸/电离(MALDI)/质谱成像（MSI）技术，研究了氮固定过程中M.truncatula根和根瘤中代谢物的分布。高效的新型MALDI基质[1,8-双（二甲基-氨基）萘，DMAN]与传统基质2,5-二羟基苯甲酸（DHB）相结合，可以检测大量有机酸、氨基酸、糖、脂类、类黄酮及其偶联物，并提高了检测覆盖率。代表性代谢物的离子密度图被提出，并与固氮过程相关。我们证明了根和根瘤之间代谢物分布的差异，以及植物和细菌突变体产生的固定和非固定根瘤之间的代谢物分布的差异。我们的研究强调了使用MSI检测植物生物学中代谢物分布差异的好处。
Symbiotic associations between leguminous plants and nitrogen-fixing rhizobia culminate in the formation of specialized organs called root nodules, in which the rhizobia fix atmospheric nitrogen and transfer it to the plant. Efficient biological nitrogen fixation depends on metabolites produced by and exchanged between both partners. The Medicago truncatula-Sinorhizobium meliloti association is an excellent model for dissecting this nitrogen-fixing symbiosis because of the availability of genetic information for both symbiotic partners. Here, we employed a powerful imaging technique - matrix-assisted laser desorption/ionization (MALDI)/mass spectrometric imaging (MSI) - to study metabolite distribution in roots and root nodules of M.truncatula during nitrogen fixation. The combination of an efficient, novel MALDI matrix [1,8-bis(dimethyl-amino) naphthalene, DMAN] with a conventional matrix 2,5-dihydroxybenzoic acid (DHB) allowed detection of a large array of organic acids, amino acids, sugars, lipids, flavonoids and their conjugates with improved coverage. Ion density maps of representative metabolites are presented and correlated with the nitrogen fixation process. We demonstrate differences in metabolite distribution between roots and nodules, and also between fixing and non-fixing nodules produced by plant and bacterial mutants. Our study highlights the benefits of using MSI for detecting differences in metabolite distributions in plant biology.