College of Resources and Environmental Sciences, Qingdao Agricultural University, Qingdao, China.
College of Resources and Environmental Sciences, Qingdao Agricultural University, Qingdao, China; Southern Regional Collaborative Innovation Center for Grain and Oil Crops in China, College of Resources and Environmental Sciences, Hunan Agricultural University, Changsha, China.
Environ Pollut. 2021 Sep 15;285:117218. doi: 10.1016/j.envpol.2021.117218. Epub 2021 Apr 24.
Oilseed rape (Brassica napus) has potential as a hyperaccumulator in the phytoremediation of cadmium (Cd)-contaminated soils. Oilseed rape varieties with higher Cd accumulation ability and Cd tolerance are ideal candidates for the hyperaccumulation of excess Cd. To explore the physiological and molecular mechanisms underlying Cd tolerance and high Cd accumulation in oilseed rape leaves, we examined two genotypes, "BN067" (Cd-sensitive with lower Cd accumulation in leaves) and "BN06" (Cd-tolerant with higher Cd accumulation in leaves). We characterized the physiological morphology, structure, subcellular distribution of Cd, cell wall components, cell chelates, and the transcriptional levels of the related genes. Greater Cd accumulation was observed in the cell walls and vacuoles of Cd-tolerant leaves, reducing Cd toxicity to the lamellar structure of the chloroplast thylakoid and leaf stomata. Higher expression of PMEs genes and lower expression of pectin methylesterase inhibitors (PMEI) genes improved pectin methylesterase (PME) activity in leaves of Cd-tolerant genotype. Stronger demethylation of pectin along with higher pectin and hemicellulose levels induced by lower pectinase and hemicellulose activities in the leaves of the Cd-tolerant genotype, resulting in higher Cd retention in the cell walls. Under Cd toxicity, higher Cd sequestration within the vacuoles of Cd-tolerant leaves was closely related to greater accumulation of Cd chelates with stronger biosynthesis in protoplasts. The results highlight the importance of using hyperaccumulation by plants to remediate our environment, and also provide a theoretical basis for the development of Cd-tolerant varieties.
油菜（甘蓝型油菜）具有在镉（Cd）污染土壤的植物修复中作为超积累植物的潜力。具有更高 Cd 积累能力和 Cd 耐性的油菜品种是超积累过量 Cd 的理想候选者。为了探索油菜叶片 Cd 耐性和高 Cd 积累的生理和分子机制，我们研究了两个基因型，“BN067”（Cd 敏感型，叶片中 Cd 积累较低）和“BN06”（Cd 耐性型，叶片中 Cd 积累较高）。我们描述了生理形态、结构、Cd 的亚细胞分布、细胞壁成分、细胞螯合物以及相关基因的转录水平。在 Cd 耐性叶片的细胞壁和液泡中观察到更高的 Cd 积累，降低了 Cd 对叶绿体类囊体片层结构和叶片气孔的毒性。PMEs 基因的高表达和果胶甲酯酶抑制剂（PMEI）基因的低表达提高了 Cd 耐性基因型叶片中 PME 的活性。果胶沿较弱的果胶酶和半纤维素活性的更强去甲基化以及较高的果胶和半纤维素水平，导致细胞壁中更高的 Cd 保留。在 Cd 毒性下，Cd 耐性叶片液泡中更高的 Cd 螯合的螯合与原质体中更强的生物合成密切相关。这些结果强调了利用植物超积累来修复我们环境的重要性，并为 Cd 耐性品种的开发提供了理论依据。
