Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture and Rural Affairs, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Wuhan, 430062, China.
Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture and Rural Affairs, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Wuhan, 430062, China.
Ecotoxicol Environ Saf. 2020 Jul 1;197:110613. doi: 10.1016/j.ecoenv.2020.110613. Epub 2020 Apr 15.
Cadmium (Cd) contaminated soil has threatened plant growth and human health. Rapeseed (Brassica napus L.), an ideal plant for phytoremediation, is an important source of edible vegetable oil, vegetable, animal fodder, green manure and biodiesel. For safe utilization of Cd polluted soil, physiological, biochemical, and molecular techniques have been used to understand mechanisms of Cd tolerance in B. napus. However, most of these researches have concentrated on vegetative and adult stages, just a few reports focus on the initial growth stage. Here, the partitioning of cadmium, gene expression level and activity of enzymatic antioxidants of H18 (tolerant genotype) and P9 (sensitive genotype) were investigated under 0 and 30 mg/L Cd stress at seedling establishment stage. Results shown that the radicle length of H18 and P9 under Cd stress were decreased by 30.33 (0.01 < P < 0.05) and 88.89% (P < 0.01) respectively. Cd concentration at cotyledon not radicle and hypocotyl in P9 was significantly higher than that in H18. The expression level of BnaHMA4c, which plays a key role in root-to-shoot translocation of Cd, was extremely higher in P9 than in H18 under both normal and Cd stress conditions. We also found that SOD, CAT and POD were more active in responding to Cd stress after 48 h, and the activity of SOD and CAT in H18 were higher than that in P9 at all observed time points. In conclusion, high activity of enzymatic antioxidants at initial Cd stress stage is the main detoxification mechanism in Cd-tolerant rapeseed, while the higher Cd transfer coefficient, driven by higher expression level of BnaHMA4c is the main mechanism for surviving radicle from initial Cd toxicity in Cd-sensitive rapeseed.
镉（Cd）污染土壤威胁着植物的生长和人类的健康。油菜（Brassica napus L.）是一种理想的植物修复植物，是食用植物油、蔬菜、动物饲料、绿肥和生物柴油的重要来源。为了安全利用镉污染土壤，已经使用生理、生化和分子技术来了解油菜对 Cd 的耐受机制。然而，这些研究大多集中在营养和成年阶段，只有少数报告集中在初始生长阶段。在这里，在幼苗定植阶段，研究了 0 和 30 mg/L Cd 胁迫下 H18（耐受基因型）和 P9（敏感基因型）的镉分配、基因表达水平和酶抗氧化剂活性。结果表明，Cd 胁迫下 H18 和 P9 的胚根长度分别减少了 30.33%（0.01<P<0.05）和 88.89%（P<0.01）。P9 中 Cd 在子叶而不是胚根和下胚轴中的浓度明显高于 H18。在正常和 Cd 胁迫条件下，在 P9 中，在根到茎部转移 Cd 中起关键作用的 BnaHMA4c 的表达水平极高于 H18。我们还发现，SOD、CAT 和 POD 在 48 h 后对 Cd 胁迫的反应更为活跃，并且在所有观察时间点，H18 中的 SOD 和 CAT 活性均高于 P9。总之，在初始 Cd 胁迫阶段，酶抗氧化剂的高活性是 Cd 耐受油菜解毒的主要机制，而 BnaHMA4c 表达水平较高导致的 Cd 转移系数较高是 Cd 敏感油菜胚根免受初始 Cd 毒性的主要机制。
