BACKGROUND Alfalfa (Medicago sativa) is the most extensively cultivated forage legume in the world, and salinity stress is the most problematic environmental factors limiting alfalfa production. To evaluate alfalfa tissue variations in response to salt stress, comparative physiological and proteomic analyses were made of salt responses in the roots and shoots of the alfalfa. METHOD A two-dimensional gel electrophoresis (2-DE)-based proteomic technique was employed to identify the differentially abundant proteins (DAPs) from salt-treated alfalfa roots and shoots of the salt tolerance cultivars Zhongmu No 1 cultivar, which was subjected to a range of salt stress concentrations for 9 days. In parallel, REL, MAD and H2O2 contents, and the activities of antioxidant enzymes of shoots and roots were determinand. RESULT Twenty-seven spots in the shoots and 36 spots in the roots that exhibited showed significant abundance variations were identified by MALDI-TOF-TOF MS. These DAPs are mainly involved in the biological processes of photosynthesis, stress and defense, carbohydrate and energy metabolism, second metabolism, protein metabolism, transcriptional regulation, cell wall and cytoskeleton metabolism, ion transpor, signal transduction. In parallel, physiological data were correlated well with our proteomic results. It is worth emphasizing that some novel salt-responsive proteins were identified, such as CP12, pathogenesis-related protein 2, harvest-induced protein, isoliquiritigenin 2'-O-methyltransferase. qRT-PCR was used to study the gene expression levels of the four above-mentioned proteins; four patterns are consistent with those of induced protein. CONCLUSION The primary mechanisms underlying the ability of alfalfa seedlings to tolerate salt stress were photosynthesis, detoxifying and antioxidant, secondary metabolism, and ion transport. And it also suggests that the different tissues responded to salt-stress in different ways.

中文翻译：

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苜蓿根和芽中早期盐胁迫响应蛋白的蛋白质组学分析。

背景技术紫花苜蓿（Medicago sativa）是世界上栽培最广泛的豆科牧草，盐分胁迫是限制紫花苜蓿生产的最成问题的环境因素。为了评估苜蓿组织对盐胁迫的反应，对苜蓿根和芽的盐反应进行了比较生理学和蛋白质组学分析。方法 采用基于二维凝胶电泳（2-DE）的蛋白质组学技术，对耐盐品种中牧一号品种盐渍处理的苜蓿根、芽进行差异丰度蛋白（DAPs）鉴定。 9 天的盐胁迫浓度范围。同时测定REL、MAD和H2O2含量，以及茎和根的抗氧化酶活性。结果 MALDI-TOF-TOF MS鉴定出27个新梢和36个根中显示出显着丰度变化的点。这些DAP主要参与光合作用、应激与防御、碳水化合物与能量代谢、二次代谢、蛋白质代谢、转录调控、细胞壁与细胞骨架代谢、离子转运、信号转导等生物学过程。同时，生理数据与我们的蛋白质组学结果有很好的相关性。值得强调的是，一些新的盐反应蛋白被鉴定出来，如CP12、发病机制相关蛋白2、收获诱导蛋白、异甘草素2'-O-甲基转移酶。qRT-PCR用于研究上述四种蛋白质的基因表达水平；四种模式与诱导蛋白一致。结论 苜蓿幼苗耐受盐胁迫的主要机制是光合作用、解毒抗氧化、次生代谢和离子转运。它还表明，不同的组织以不同的方式对盐胁迫作出反应。