College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311121, China.
State Key Laboratory of Plant Physiology and Biochemistry, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China.
J Hazard Mater. 2020 Jul 5;393:122411. doi: 10.1016/j.jhazmat.2020.122411. Epub 2020 Feb 25.
This study clarifies the mechanisms of Cd uptake, translocation and detoxification in Populus cathayana Rehder females and males, and reveals a novel strategy for dioecious plants to cope with Cd contamination. Females exhibited a high degree of Cd uptake and root-to-shoot translocation, while males showed extensive Cd accumulation in roots, elevated antioxidative capacity, and effective cellular and bark Cd sequestration. Our study also found that Cd is largely located in epidermal and cortical tissues of male roots and leaves, while in females, more Cd was present in vascular tissues of roots and leaves, as well as in leaf mesophyll. In addition, the distributions of sulphur (S) and phosphorus (P) were very similar as that of Cd in males, but the associations were weak in females. Scanning electron microscopy and energy spectroscopy analyses suggested that the amounts of tissue Cd were positively correlated with P and S amounts in males, but not in females (a weak correlation between S and Cd). Transcriptional data suggested that Cd stress promoted the upregulation of genes related to Cd uptake and translocation in females, and that of genes related to cell wall biosynthesis, metal tolerance and secondary metabolism in males. Our results indicated that coordinated physiological, microstructural and transcriptional responses to Cd stress endowed superior Cd tolerance in males compared with females, and provided new insights into mechanisms underlying sexually differential responses to Cd stress.
本研究阐明了雌性和雄性白杨中 Cd 的吸收、转运和解毒机制，揭示了雌雄异株植物应对 Cd 污染的一种新策略。雌性表现出较高的 Cd 吸收和根到茎的转运能力，而雄性则在根部积累了大量的 Cd，提高了抗氧化能力，并有效地将细胞和树皮中的 Cd 固定。我们的研究还发现，Cd 主要位于雄性根和叶的表皮和皮层组织中，而在雌性中，更多的 Cd 存在于根和叶的维管束组织以及叶肉中。此外，S 和 P 的分布与 Cd 在雄性中的分布非常相似，但在雌性中相关性较弱。扫描电子显微镜和能谱分析表明，雄性组织中 Cd 的含量与 P 和 S 的含量呈正相关，但在雌性中则没有（S 和 Cd 之间的相关性较弱）。转录组数据表明，Cd 胁迫促进了雌性中与 Cd 吸收和转运相关基因的上调，以及雄性中与细胞壁生物合成、金属耐受性和次生代谢相关基因的上调。我们的结果表明，对 Cd 胁迫的协调生理、微观结构和转录响应赋予了雄性比雌性更高的 Cd 耐受性，并为 Cd 胁迫下性别差异响应的机制提供了新的见解。
