Chongqing Engineering Research Center for Rapeseed, College of Agronomy and Biotechnology, Academy of Agricultural Sciences, Southwest University, Chongqing, 400716, China.
Environ Sci Pollut Res Int. 2018 Nov;25(32):32433-32446. doi: 10.1007/s11356-018-3227-0. Epub 2018 Sep 19.
Cadmium (Cd) stress is one of the most serious threats to agriculture in the world. Oilseed rape (Brassica napus L.) is an important oil crop; however, Cd can easily accumulate in rapeseed and thus harm human health through the food chain. In the first experiment, our purpose was to measure the Cd accumulation in mature B. napus plants and its influences on fatty acid composition. The results showed that most Cd was accumulated in the root, and the seed fatty acid content was considerably different at different Cd toxicity levels. In the second experiment, 7-day-old B. napus seedlings stressed by Cd (1 mM) for 0 h (CK-0h), 24 h (T-24h), or 72 h (T-72h) were submitted to physiological and biological analyses, RNA-Seq and qRT-PCR. In total, 5469 and 6769 differentially expressed genes (DEGs) were identified in the comparisons of "CK-0h vs T-24h" and "CK-0h vs T-72h", respectively. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses showed that the photosynthetic and glutathione (GSH) pathways were significantly enriched in response to Cd stress. Key factors in the response to Cd stress included BnPCS1, BnGSTU12, BnGSTU5, and BnHMAs. The transcription factors BnWRKY11 (BnaA03g51590D), BnWRKY28 (BnaA03g43640D), BnWRKY33 (BnaA03g17820D), and BnWRKY75 (BnaA03g04160D) were upregulated after Cd exposure. The present study revealed that upregulation of the genes encoding GST and PCS under Cd stress promoted the formation of low-molecular weight complexes (PC-Cd), and upregulation of heavy metal ATPase genes induced PC-Cd transfer to vacuoles. These findings may provide the basis for the molecular mechanism of the response of B. napus to Cd.
镉（Cd）胁迫是世界范围内农业面临的最严重威胁之一。油菜（Brassica napus L.）是一种重要的油料作物；然而，Cd 很容易在油菜中积累，从而通过食物链危害人类健康。在第一个实验中，我们的目的是测量成熟油菜植株中 Cd 的积累及其对脂肪酸组成的影响。结果表明，大部分 Cd 积累在根部，种子脂肪酸含量在不同 Cd 毒性水平下有明显差异。在第二个实验中，用 Cd（1 mM）处理 7 天大的油菜幼苗 0 h（CK-0h）、24 h（T-24h）或 72 h（T-72h），然后进行生理和生物分析、RNA-Seq 和 qRT-PCR。总共鉴定出在“CK-0h vs T-24h”和“CK-0h vs T-72h”比较中差异表达的基因（DEGs）分别为 5469 和 6769 个。基因本体论（GO）和京都基因与基因组百科全书（KEGG）途径分析表明，在 Cd 胁迫响应中，光合作用和谷胱甘肽（GSH）途径显著富集。Cd 应激响应的关键因素包括 BnPCS1、BnGSTU12、BnGSTU5 和 BnHMAs。转录因子 BnWRKY11（BnaA03g51590D）、BnWRKY28（BnaA03g43640D）、BnWRKY33（BnaA03g17820D）和 BnWRKY75（BnaA03g04160D）在 Cd 暴露后上调。本研究表明，Cd 胁迫下 GST 和 PCS 编码基因的上调促进了低分子量复合物（PC-Cd）的形成，重金属 ATP 酶基因的上调诱导 PC-Cd 向液泡转移。这些发现可能为油菜响应 Cd 的分子机制提供依据。
