Pilon-Smits Elizabeth A H
Biology Department, Colorado State University, Fort Collins, CO 80523, USA.
Plants (Basel). 2019 Jun 30;8(7):197. doi: 10.3390/plants8070197.
Plants accumulate and tolerate Se to varying degrees, up to 15,000 mg Se/kg dry weight for Se hyperaccumulators. Plant Se accumulation may exert positive or negative effects on other species in the community. The movement of plant Se into ecological partners may benefit them at low concentrations, but cause toxicity at high concentrations. Thus, Se accumulation can protect plants against Se-sensitive herbivores and pathogens (elemental defense) and reduce surrounding vegetation cover via high-Se litter deposition (elemental allelopathy). While hyperaccumulators negatively impact Se-sensitive ecological partners, they offer a niche for Se-tolerant partners, including beneficial microbial and pollinator symbionts as well as detrimental herbivores, pathogens, and competing plant species. These ecological effects of plant Se accumulation may facilitate the evolution of Se resistance in symbionts. Conversely, Se hyperaccumulation may evolve driven by increasing Se resistance in herbivores, pathogens, or plant neighbors; Se resistance also evolves in mutualist symbionts, minimizing the plant's ecological cost. Interesting topics to address in future research are whether the ecological impacts of plant Se accumulation may affect species composition across trophic levels (favoring Se resistant taxa), and to what extent Se hyperaccumulators form a portal for Se into the local food chain and are important for Se cycling in the local ecosystem.
植物对硒的积累和耐受程度各不相同，对于硒超积累植物而言，其干重中硒的积累量可达15000毫克/千克。植物对硒的积累可能会对群落中的其他物种产生正面或负面影响。植物中的硒向生态伙伴转移，在低浓度时可能对它们有益，但在高浓度时会导致毒性。因此，硒的积累可以保护植物免受对硒敏感的食草动物和病原体的侵害（元素防御），并通过高硒凋落物的沉积减少周围植被的覆盖（元素化感作用）。虽然超积累植物对硒敏感的生态伙伴有负面影响，但它们为耐硒伙伴提供了生态位，包括有益的微生物和传粉者共生体，以及有害的食草动物、病原体和竞争性植物物种。植物硒积累的这些生态效应可能促进共生体中抗硒性的进化。相反，硒超积累可能是由食草动物、病原体或植物邻体中抗硒性的增强所驱动的；共生体中也会进化出抗硒性，从而使植物的生态成本降至最低。未来研究中值得探讨的有趣话题包括：植物硒积累的生态影响是否会影响不同营养级的物种组成（有利于抗硒类群），以及硒超积累植物在多大程度上形成了硒进入当地食物链的通道，对当地生态系统中的硒循环又有多重要。
