Department of Plant Biology, Institute of Biology, University of Campinas, PO Box 6109, 13083-970, Campinas, São Paulo, Brazil; Department of Botany, Federal University of São Carlos, PO Box 676, 13565-905, São Carlos, São Paulo, Brazil.
Instituto Federal de Educação, Ciência e Tecnologia Goiano, Campus Rio Verde , Polo de Inovação em Bioenergia e Grãos, Rio Verde, GO, Brazil.
Ecotoxicol Environ Saf. 2020 Jun 1;195:110450. doi: 10.1016/j.ecoenv.2020.110450. Epub 2020 Apr 1.
Due to diverse human activities zinc (Zn) may reach phytotoxic levels in the soil. Here, we evaluated the differential sensibility of three Brazilian tree species from the Fabaceae to increasing soil Zn concentrations and its physiological response to cope with excess Zn. A greenhouse experiment was conducted with the species: Mimosa caesalpiniaefolia, Erythrina speciosa and Schizolobium parahyba, and the addition of 0, 200, 400 and 600 mg Zn kg to the soil. Plants were harvested after three months of cultivation, and growth, root symbiosis, biochemical markers and elemental composition were analyzed. Soil Zn addition reduced seedling growth, irrespective of the species, with a strong reduction in M. caesalpiniaefolia. Regarding root symbiosis, in N-fixing species, nitrogenase activity was reduced by the highest Zn concentrations. Zn addition caused plants nutritional imbalances, mainly in roots. The content of photosynthetic pigments in leaves decreased up to 40%, suggesting that high Zn contents interfered with its biosynthesis, and altered the content of foliar polyamines and free amino acids, depending on the species and the soil Zn concentration. Zn toxicity in M. caesalpiniaefolia plants was observed at available soil Zn concentrations greater than 100 mg kg (DTPA-extractable), being the most sensitive species and E. speciosa was moderately sensitive. S. parahyba was a moderately tolerant species, which seems to be related to polyamines accumulation and to mycorrhizal association. This last species has the potential for revegetation of areas with moderately high soil Zn concentration and for phytostabilization purposes. Future research evaluating the tolerance to multiple metal stress under field conditions should confirm S. parayba suitability in Zn contaminated areas of tropical regions.
由于人类的各种活动，土壤中的锌（Zn）含量可能达到毒害水平。在这里，我们评估了三种来自豆科的巴西树种对土壤中锌浓度增加的敏感性差异，以及它们应对过量锌的生理反应。在温室中进行了一项实验，使用了物种：金合欢（Mimosa caesalpiniaefolia）、巴西含羞草（Erythrina speciosa）和巴西橡胶树（Schizolobium parahyba），并向土壤中添加 0、200、400 和 600 mg Zn kg。在种植三个月后收获植物，并分析生长、根共生、生化标志物和元素组成。无论物种如何，土壤锌的添加都会降低幼苗的生长，而金合欢的生长受影响最大。关于根共生，在固氮物种中，固氮酶活性在最高锌浓度下降低。锌的添加导致植物营养失衡，主要是在根部。叶片中光合色素的含量下降了 40%，这表明高锌含量干扰了其生物合成，并改变了叶片多胺和游离氨基酸的含量，具体取决于物种和土壤锌浓度。在金合欢植株中观察到可用土壤锌浓度大于 100 mg kg（DTPA 可提取）时的锌毒性，金合欢是最敏感的物种，巴西含羞草是中度敏感的。巴西橡胶树是一种中度耐受的物种，这似乎与多胺的积累和菌根的共生有关。该物种具有在土壤锌浓度适中的地区进行植被恢复和进行植物稳定化的潜力。未来在野外条件下评估对多种金属胁迫的耐受性的研究应证实巴西橡胶树在热带地区锌污染地区的适宜性。
