Proteomic changes in the xylem sap of Brassica napus under cadmium stress and functional validation
Proteomic changes in the xylem sap of Brassica napus under cadmium stress and functional validation
复制标题
镉胁迫下甘蓝型油菜木质部汁液的蛋白质组变化及功能验证
DOI：
10.1186/s12870-019-1895-7
复制
发表时间：
2019-06-26
影响因子：
5.3
通讯作者：
Zhang, Zhenhua
中科院分区：
文献类型：
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作者：
Luo, Jin-Song;Zhang, Zhenhua
维管束植物的木质部汁液主要将水分和矿物质营养从根部运输到地上部，也运输重金属，如镉。木质部汁液中蛋白质组的变化是植物解毒Cd的重要机制。然而，木质部汁液中的蛋白质对Cd的反应尚不清楚。在这里，我们利用无标记鸟枪蛋白质组学方法研究了Cd胁迫对甘蓝型油菜木质部汁液蛋白质组的影响，以阐明植物对Cd胁迫的响应机制。我们鉴定和量化了672种蛋白质；67%被预测为分泌型，11%(73种蛋白质)是镉处理样本所特有的。Cd胁迫引起了28种木质部汁液蛋白丰度的显著变化。在这些蛋白质中，受影响最大的代谢途径与细胞壁修饰、应激/氧化还原酶以及脂肪和蛋白质代谢有关。我们从功能上验证了植物防御素类蛋白BnPDFL，它属于胁迫/氧化还原酶类别，是Cd处理样品所特有的，在Cd耐性中发挥了积极的作用。亚细胞定位分析表明，BnPDFL定位于细胞壁。体外镉结合实验表明，BnPDFL具有镉螯合活性。BnPDFL异源过表达显著提高了大肠杆菌和拟南芥对Cd的耐受性。主要在根维管束中表达的拟南芥植物防御素基因AtPDF2.3和AtPDF2.2的功能中断显著降低了其对Cd的耐性。甘蓝型油菜几种木质部汁液蛋白对Cd处理有不同程度的诱导，植物防御素在Cd耐性中起积极作用。
The xylem sap of vascular plants primarily transports water and mineral nutrients from the roots to the shoots and also transports heavy metals such as cadmium (Cd). Proteomic changes in xylem sap is an important mechanism for detoxifying Cd by plants. However, it is unclear how proteins in xylem sap respond to Cd. Here, we investigated the effects of Cd stress on the xylem sap proteome of Brassica napus using a label-free shotgun proteomic approach to elucidate plant response mechanisms to Cd toxicity. We identified and quantified 672 proteins; 67% were predicted to be secretory, and 11% (73 proteins) were unique to Cd-treated samples. Cd stress caused statistically significant and biologically relevant abundance changes in 28 xylem sap proteins. Among these proteins, the metabolic pathways that were most affected were related to cell wall modifications, stress/oxidoreductases, and lipid and protein metabolism. We functionally validated a plant defensin-like protein, BnPDFL, which belongs to the stress/oxidoreductase category, that was unique to the Cd-treated samples and played a positive role in Cd tolerance. Subcellular localization analysis revealed that BnPDFL is cell wall-localized. In vitro Cd-binding assays revealed that BnPDFL has Cd-chelating activity. BnPDFL heterologous overexpression significantly enhanced Cd tolerance in E. coli and Arabidopsis. Functional disruption of Arabidopsis plant defensin genes AtPDF2.3 and AtPDF2.2, which are mainly expressed in root vascular bundles, significantly decreased Cd tolerance. Several xylem sap proteins in Brassica napus are differentially induced in response to Cd treatment, and plant defensin plays a positive role in Cd tolerance.