镉在三色堇中的积累及亚细胞与化学形态分布

通过营养液培养实验,研究了在不同Cd浓度(0、0.01、0.05、0.1、0.2、0.3、0.4 mmol·L-1)处理下,三色堇地下部和地上部中Cd的含量与积累特征,进一步分析了Cd在三色堇体内的亚细胞分布特征和化学形态分布特征.结果表明,三色堇体内Cd积累量随着Cd浓度的增加而不断增加,对Cd具有很高的积累能力,是一种潜在的Cd超富集植物.三色堇地下部和地上部大部分的Cd分布在可溶组分和细胞壁中,而在细胞器中的分布较少.随着Cd处理浓度的增加,地下部细胞壁中镉的分配比例呈增加趋势.植株中大部分的Cd以乙醇提取态和水取提态存在,随着Cd处理浓度的增加,地上部中活性强、毒性较高的乙醇提取态和水提取态Cd分配比例总和减少,而活性较弱、毒性较低的氯化钠提取态和醋酸提取态Cd分配比例增加,这有利于降低总镉的相对毒性.因此,液泡区隔化、细胞壁固持和化学形态转化可能是三色堇应对Cd胁迫的重要耐性机制.

Accumulation,subcellular distribution and chemical forms of cadmium in Viola tricolor L.

A hydroponic experiment was conducted to investigate the accumulation, subcellular distribution and chemical forms of Cd in the root and leaf of Viola tricolor L. with different Cd treatments (0, 0.01, 0.05, 0.1, 0.2, 0.3 and 0.4 mmol·L^-1). The results showed that Cd accumulation increased in Viola tricolor L. with elevating cadmium supply and was identified as new potential hyperaccumulator with high accumulation capacity of Cd. Majority of total Cd was found in soluble fraction and cell wall in the roots of plant, while only a small quantity of Cd distributed in organelles. As to chemical forms distribution of Cd, a large quantity of Cd existed in water-and ethanol-extractable forms both in root and shoots of plant. In addition, with increasing Cd supply in the medium, the Cd accumulation percentages in NaCl- and HAc- extractable fractions increased, whereas Cd extracted by ethanol and water decreased. Therefore, cell wall binding, vacuolar compartmentalization and transferring of chemical forms were supposed to be the main tolerance mechanisms to Cd for Viola tricolor L. with Cd stress.