马缨丹对镉的生长响应及其富集、转运和亚细胞分布特点研究

镉是植物非必需且生物毒性最强的重金属元素之一，然而镉富集植物能通过一定的响应机制来减少镉对自身产生的毒害，且不同植物之间镉的解毒机制存在差异。马缨丹（Lantana camara L.）是四川汉源铅锌矿区镉污染土壤的修复植物，但是关于其镉的分布特征和解毒机制并不明确。因此本文采用盆栽模拟试验，分别设置0（对照，不添加镉）、30、90、150、210 mg·kg-1镉5个处理，研究马缨丹对镉的富集、转运及其亚细胞分布特点，探讨马缨丹对镉的耐性和解毒机制，以期为植物耐镉的生理和分子生物学机制提供一定的理论依据。结果表明：镉质量分数低于90 mg·kg-1时对马缨丹生长没有影响，而镉质量分数高于150 mg·kg-1时对马缨丹生长有显著的抑制作用；随着镉质量分数的增加，马缨丹各器官中镉的质量分数逐渐增加，表现为根＞茎＞叶，且其转运系数小于1，表明马缨丹对镉有较强的根部滞留能力，可限制过量的镉向地上部器官的转运，减少镉对地上部的毒害，这可能是马缨丹耐受镉胁迫的机制之一；随着镉质量分数的增加，马缨丹地下部和地上部的镉富集量总体上均呈增加趋势，在210 mg·kg-1镉处理时，均达到最大值，分别为142.8和1031.6μg·plant-1，不同质量分数镉处理下，马缨丹地上部的镉富集量较大，占全株镉富集量的94.0%~88.3%；镉在马缨丹根和叶细胞可溶性组分中的分配比例最高，分别占62.1%~54.2%和59.8%~52.6%，其次在细胞壁中，分别占23.8%~34.4%和28.7%~39.5%，在细胞器和细胞膜中的较低，表明可溶性组分和细胞壁是镉在马缨丹根和叶细胞中的主要分布位点，液泡区隔化和细胞壁固持可能是马缨丹对镉的重要解毒和耐性机制之一。

Effects of Cadmium on Growth Response of Lantana camaraL. and Its Accumulation,Translocation and Subcellular Distribution of Cd

Cadmium （Cd） is one of the non-essentials of plant and the most toxic heavy metal elements in biological,however, Cd enrichment plant can reduce toxic of Cd via certain mechanisms, and there are some differences in detoxification mechanisms of Cd for different plant.Lantana camara L. is valuable in the phytoremediation of Cd-contaminated soil in Hanyuan mine area. However, distribution and detoxification mechanisms ofL.camara for cadmium remain poorly understood. In order to explore the tolerance and detoxification mechanisms of Cd ofL.camara, this study investigated the Cd accumulation, translocation and subcellular distribution inL.camara gorwn in pot which contain 0, 30, 90, 150 or 210 mg·kg-1Cd. The results showed that when the concentrations of application Cd were less than 90 mg·kg-1, the growth ofL. camara was not influenced, while the concentrations of application Cd were higher than 150 mg·kg-1, the growth ofL. camara was inhibited significantly. With the increasing of concentrations of application Cd, the concents of Cd in different organs ofL. camara increased gradually, and it’s in sequence as follows： roots〉 stems〉 leaves. Meanwhile, the translocation factor （TF） of Cd ofL. camara was less than 1 under different concentrations of Cd application. It suggested thatL. camara had a strong root retention capacity of Cd, which can reduce the toxicity of Cd to the organs of shoot. With the increasing of concentrations of application Cd, the Cd accumulation in roots and shoots increased gradually, and reached the maximum at 210 mg·kg-1 Cd, and was 142.8μg·plant-1and 1,031.6μg·plant-1, respectively. Cd accumulation in shoots was larger than roots, and accounting for 94.0%~88.3% in whole plant. The proportion of Cd in soluble fraction in roots and leaves were highest, followed by cell wall, organelles and membranes were lowest. The allocation proportion of Cd in soluble fraction in roots and leaves were 62.1%~54.2% and 59.8%~52.6% respectively, in cell wall were 23.8%~34.4% and 28.7%~39