Cd胁迫下芦苇体内氯化钠提取态镉及γ-谷氨酰半胱氨酸合成酶活性研究

Study on the Sodiumchloride-Extraction Cadmium(SCd) and Gamma-Glutamylcysteine Synthetase Activity in Phragmites australis Under Cd Stress

芦苇(Phragmites australis)对污染水体重金属Cd具有极强的富集积累能力,能有效减少生长环境中的Cd含量。Cd被芦苇植株吸收后会转化为不同形态存在,其中与蛋白质结合的氯化钠提取态镉(SCd)是芦苇体内的主要形态。为研究不同Cd浓度环境中芦苇体内SCd含量及γ-谷氨酰半胱氨酸合成酶(γ-GCS)活性变化特征,采用5种浓度氯化镉溶液(0.5、1.0、2.0、3.0和5.0 mmol·L-1)对芦苇进行灌溉,然后测定不同生长时期的芦苇在镉胁迫下植株内SCd的积累量和γ-GCS活性的变化。结果显示:(1) Cd浓度增加时,芦苇植株根、茎、叶的SCd积累量呈现先增加后减少的趋势;(2)芦苇植株各部位不同时期镉积累量有所不同,成熟期时积累量达到最大。根部SCd的积累量为3 984.16 mg·kg-1,是茎部的7.33倍,叶部的4.83倍;(3)在镉溶液浓度小于3.0 mmol·L-1时,芦苇根茎叶中γ-GCS活性随灌溉浓度增加而增加;镉溶液浓度大于3.0 mmol·L-1时γ-GCS活性被抑制。

Phragmites australis has a strong capacity of the absorption to heavy metal cadmium,which can effectively reduce the cadmium content of its growing environment.After being abstracted by reed,the cadmium is converted into different forms.The cadmium extracted by sodium chloride(SCd)is the main form in reed.In order to study the effects of different concentrations of cadmium on the SCd and the activity of gamma-glutamylcysteine synthetase(γ-GCS)in reed,the cadmium chloride solutions of 5 levels(0.5,1.0,2.0,3.0 and 5.0 mmol·L^-1)were used to irrigate the Phragmites australis at different growth stages,and the accumulation of cadmium(SCd)and the change activity ofγ-GCS in reed were measured.The results show that:(1)When the concentration of cadmium chloride solution increased,the accumulation amount of SCd in the roots,stems,and leaves of reed first increased and then decreased;(2)The accumulation amount of SCd in different parts of the reed was different at different stages.During the mature stage,the accumulation amount of SCd reached the maximum.It was 3 984.16 mg·kg-1 in root,which was 7.33 times as that in the stems,and 4.83 times as that in leaves;(3)When the concentration of cadmium chloride solution was less than 3.0 mmol·L^-1,the activity ofγ-GCS in roots,stems and leaves of reeds increased with the increase of concentration of cadmium chloride solution.When the concentration of cadmium chloride solution was greater than 3.0 mmol·L^-1,the activity ofγ-GCS was suppressed.