水杨酸对铜胁迫下菊芋的生理调控及根系FTIR分析

Physiological regulation of salicylic acid on Helianthus tubeuosus upon copper stress and root FTIR analysis

摘要:

为阐明水杨酸（salicylic acid，SA）对菊芋吸收铜的影响机理，以耐铜性差异较大的徐州菊芋（Helianthus tubeuosus）和潍坊菊芋作为试验材料，通过盆栽试验，探究外源SA对铜胁迫下菊芋的光合作用、叶片抗氧化系统及必需矿质营养元素吸收的影响，并对其耐铜机理进行探究。结果表明，300 mg/kg铜胁迫抑制了两地菊芋光合电子传递效率和PSⅡ活性，对抗氧化系统产生损伤并造成膜脂过氧化，显著增加了根、茎、叶中铜含量，同时削弱了菊芋对钾、钙、镁和锌的吸收能力。喷施1 mmol/L外源SA可通过调控根系中各官能团的比例，加强其对Cu²⁺的固定作用，促进矿质营养元素的吸收及渗透调节物质的积累，提高菊芋抗氧化和光合作用能力，有效缓解铜对菊芋生长的抑制作用。本研究初步揭示了SA对铜胁迫下菊芋的生理调控，可为种植菊芋修复土壤铜污染提供科学参考和依据。

Abstract:

Phytoremediation plays an important role in the treatment of heavy metal pollution in soil. In order to elucidate the mechanism of salicylic acid (SA) on copper absorption, seedlings from Xuzhou (with strong Cu-tolerance) and Weifang Helianthus tuberosus cultivars (with weak Cu-tolerance) were selected for pot culture experiments. 1 mmol/L SA was sprayed upon 300 mg/kg soil copper stress, and the photosynthesis, leaf antioxidant system, several essential mineral nutrients and the changes of root upon copper stress were analyzed to explore the mechanism of copper resistance. The results showed that Pn, Tr, Gs and Ci upon copper stress decreased significantly compared to the control group. Meanwhile, chlorophyll a, chlorophyll b and carotenoid decreased with significant increase in initial fluorescence (F₀), maximum photochemical quantum yield of PSⅡ (Fv/Fm), electron transfer rate (ETR) and photochemical quenching coefficient (qP) content all decreased. The ascorbic acid (AsA) content was decreased, the glutathione (GSH) value was increased, the superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) activity in the leaves were decreased, and the peroxidase (POD) activity was significantly increased. SA increased the Cu content in the ground and root system, and weakened the nutrient uptake capacity of K, Ca, Mg, and Zn in the root stem and leaves. Spray of exogenous SA can maintain the opening of leaf stomata, improve the adverse effect of copper on photosynthetic pigment and PSⅡ reaction center. Mediating the SOD and APX activity started the AsA-GSH cycle process, effectively regulated the antioxidant enzyme system in chrysanthemum taro, significantly reduced the copper content of all parts of the plant, and improved the ion exchange capacity in the body. External SA increased the content of the negative electric group on the root by changing the proportion of components in the root, promoted the absorption of mineral nutrient elements and the accumulation of osmoregulatory substances, strengthened the fixation effect of the root on metal copper, and avoided its massive accumulation in the H. tuberosus body, so as to alleviate the inhibitory effect of copper on plant growth. The study revealed the physiological regulation of SA upon copper stress, and provided a theoretical basis for planting H. tuberosus to repair soil copper pollution.