外源钙对镉胁迫下荻种子萌发和幼苗生长的影响

Effects of exogenous Ca on seed germination and seedling growth of Miscanthus sacchariflorus under Cd stress

钙作为一种必需元素,对植物根系发育、茎叶生长、细胞壁的合成等具有重要作用。本研究以能源植物荻(Miscanthus sacchariflorus)作为对象,通过种子萌发实验,比较250μmol·L^(-1)Cd胁迫下外源Ca的加入对植物种子萌发、生长参数、抗氧化酶活性、膜损伤程度、光合色素和渗透调节物质含量等的影响,探讨外源Ca对Cd胁迫诱导的种子萌发受阻和幼苗氧化损伤的缓解作用。结果表明:250μmol·L^(-1)CdCl_(2)胁迫导致植物体内的ROS含量增加,细胞的氧化损伤程度加重,致使荻的萌发指标显著下降,幼苗生长受到明显抑制;外源Ca的加入则能够通过增强脂肪酶和蛋白酶活性,将荻种子发芽率、发芽势、发芽指数和活力指数提高至单独Cd胁迫的1.22、1.33、1.32和1.96倍;通过减少植物对Cd的摄入、增加游离脯氨酸含量、维持膜稳定性等途径减弱Cd诱导的氧化损伤,缓解Cd诱导的植物根长、鲜重、光合色素含量减少的情况,降低荻幼苗体内的SOD、POD、CAT活性;其缓解作用随外源Ca浓度增加表现出先增强后减弱的变化趋势,5 mmol·L^(-1)CaCl_(2)处理时缓解Cd胁迫的效果最好。这为今后利用Ca化合物修复Cd污染土壤提供了一定的科学依据。

Calcium,an essential element for plants,plays a crucial role in root development,stem and leaf growth,and cell wall synthesis.To investigate the effects of Ca in alleviating Cd-induced seed germination delay and oxidative damage of seedlings,we examined the effects of Ca addition on seed germination,growth parameters,activities of antioxidant enzymes,degree of membrane damage and contents of photosynthetic pigments,and os-moregulation substances in the presence of 250μmol·L^(-1)Cd,with the energy plant Miscanthus sacchariflorus as a research object.Results showed that 250μmol·L^(-1)CdCl_(2)exposure increased ROS content and aggravated cellular oxidative damage,resulting in a significant decrease in germination indicators and a significant inhibition of seed-ling growth.In contrast,addition of Ca increased germination rate,germination potential,germination index,and vitality index of M.sacchariflorus seeds by 1.22,1.33,1.32,and 1.96 times as compared to the seeds treated by Cd alone by increasing the activity of lipase and protease.Cd-induced oxidative damage was weakened and the re-duction of root growth,fresh weight and photosynthetic pigment contents was mitigated by decreasing Cd uptake,increasing free proline content,and stabilizing membrane integrity,thereby attenuating the activities of SOD,POD,and CAT.The mitigation effects of Ca on the phytotoxicity of Cd were increased initially,and decreased with increasing Ca concentrations.5 mmol·L^(-1)CaCl_(2)had the strongest effect in alleviating the phytotoxicity of Cd in M.sacchariflorus.Our results provide scientific evidence in the phytoremediation of Cd-polluted soil by exogenous Ca.