Junren Chen

Copper induced oxidative stresses, antioxidant responses and phytoremediation potential of Moso bamboo ( Phyllostachys pubescens )

Moso bamboo is recognized as phytoremediation plant due to production of huge biomass and high tolerance in stressed environment. Hydroponics and pot experiments were conducted to investigate mechanism of copper tolerance and to evaluate copper accumulation capacity of Moso bamboo. In hydroponics experiment there was non significant variation in MDA contents of leaves compared with control. SOD and POD initially indicated enhancing trend with application of 5 μM Cu and then decreased consistently with application of 25 and 100 μM Cu. Application of each additional increment of copper have constantly enhanced proline contents while maximum increase of proline was observed with application of 100 μM copper. In pot experiment chlorophyll and biomass initially showed increasing tendency and decreased gradually with application of each additional increment of Cu. Normal growth of Moso bamboo was observed with application of 100 mg kg−1 copper. However, additional application of 300 or 600 mg kg−1 copper had significantly inhibited growth of Moso bamboo. The concentration of Cu in Moso bamboo has attained the levels of 340, 60, 23 mg kg−1 in roots, stems and leaves respectively. The vacuoles were the main organs which accumulated copper and reduced toxicity of copper as studied by TEM-DEX technology.

Lead accumulation and tolerance of Moso bamboo (Phyllostachys pubescens) seedlings: applications of phytoremediation *

A hydroponics experiment was aimed at identifying the lead (Pb) tolerance and phytoremediation potential of Moso bamboo (Phyllostachys pubescens) seedlings grown under different Pb treatments. Experimental results indicated that at the highest Pb concentration (400 μmol/L), the growth of bamboo seedlings was inhibited and Pb concentrations in leaves, stems, and roots reached the maximum of 148.8, 482.2, and 4282.8 mg/kg, respectively. Scanning electron microscopy revealed that the excessive Pb caused decreased stomatal opening, formation of abundant inclusions in roots, and just a few inclusions in stems. The ultrastructural analysis using transmission electron microscopy revealed that the addition of excessive Pb caused abnormally shaped chloroplasts, disappearance of endoplasmic reticulum, shrinkage of nucleus and nucleolus, and loss of thylakoid membranes. Although ultrastructural analysis revealed some internal damage, even the plants exposed to 400 μmol/L Pb survived and no visual Pb toxicity symptoms such as necrosis and chlorosis were observed in these plants. Even at the highest Pb treatment, no significant difference was observed for the dry weight of stem compared with controls. It is suggested that use of Moso bamboo as an experimental material provides a new perspective for remediation of heavy metal contaminated soil owing to its high metal tolerance and greater biomass.摘要目的探索毛竹在修复铅污染土壤的植物修复潜力。创新点使用了毛竹作为一种全新的植物修复材料进行研究。 得到了毛竹幼苗在铅胁迫下的生长与生理反应情况, 不同植物组织对铅的吸收与积累情况, 铅胁迫下毛竹幼苗表层与细胞超微结构的特征。方法根系形态分析(图3)、 植物重金属含量分析(表1)、 扫描电镜分析(图4)和透射电镜分析(图5)。结论各组织部位铅浓度的值揭示了, 毛竹是一个很好的固定铅污染土壤的植物材料; 但是由于毛竹茎的高生物量, 也可以作为铅污染土壤的植物修复材料。 在0∼200 μmol/L铅处理下, 毛竹的生物量与根系形态没有显著性差异, 生长正常未出现中毒症状。 通过扫描电镜观察铅胁迫导致叶片的气孔减少, 根与茎内含物增多。 通过透射电镜观察高浓度的铅胁迫导致部分细胞内部叶绿体变形、 内质网消失、 细胞核与核仁缩小和类囊体膜消失。 尽管超微结构观察到细胞内部的损害, 但是未出现视觉的毒性症状。 毛竹铅的高耐性与茎的高生物量, 提供了毛竹作为材料修复土壤重金属铅更大的可能性。

Cadmium-induced oxidative stress, response of antioxidants and detection of intracellular cadmium in organs of moso bamboo (Phyllostachys pubescens) seedlings

Moso bamboo (Phyllostachys pubescens (Pradelle) Mazel ex J.Houz.) is recognized as a potential phytoremediation plant due to its huge biomass and high tolerance to environmental stresses. The objectives of this study were to investigate mechanism related to cadmium (Cd) tolerance and to evaluate Cd accumulation capacity of moso bamboo. The results of the pot experiment showed that Cd accumulation by bamboo increased with increasing the Cd levels in soil and the values in stem ranged from 28.51 to 132.13 mg kg(-1). Meanwhile chlorophyll in leaves and total biomass showed a decreasing trend. The bioaccumulation factors (BAF) for roots and stem in all the treatments were more than 1.0 and the translocation factor (TF) ranged from 0.70 to 1.06. In hydroponics experiment, the concentrations of malondialdehyde (MDA) in the leaves were significantly increased in Cd treated plants as compared with control. The activities of superoxide dismutase (SOD) and peroxidase (POD) were enhanced at initial stage and then decreased consistently with the increase of Cd addition. The proline concentrations were also increased due to the presence of Cd, particularly at 25 μM Cd treatment. According to TEM-EDX analysis, the cytoplasm was the main site for accumulation of Cd in moso bamboo. On the basis of overall results, it is suggested that moso bamboo could be successfully used for the remediation of low Cd (no more than 5 mg kg(-1)) contaminated soils.

Effect of lead (Pb) on antioxidation system and accumulation ability of Moso bamboo (Phyllostachys pubescens)

The antioxidation system and accumulation ability of Moso bamboo (Phyllostachys pubescens), which is a valuable remediation material with large biomass and rapid growth rate were studied in hydroponics and pot experiments. In hydroponics experiment, TBARS concentrations and SOD activities decreased with increase of Pb treatments. The activities of POD boost up with elevated Pb treatments, and reached peak level with application of 400μM Pb. Proline concentrations reduced with application of 20μM Pb and then enhanced consistently with application of 100 and 400μM Pb. The biomass of Moso bamboo improved with increase of Pb treatments upto 400mgkg-1, and then decreased with application of each additional increment of Pb in pot experiment. Application of 800mgkg-1 Pb showed significant increase of photosynthetic pigments, however, non significant variation was observed for other treatments. The Pb concentration in roots, stems and leaves attained 523mgkg-1, 303mgkg-1 and 222mgkg-1 respectively with application of 1600mgkg-1 Pb compared with control. Analysis of TEM-EDX revealed that Pb in cell was mostly concentrated in cytoplasm then in cell wall and followed by vacuole. It is concluded that Moso bamboo may be potential remediation species for phytoremediation in low Pb contaminated soils.

Cu induced changes of ultrastructure and bioaccumulation in the leaf of Moso bamboo (Phyllostachys pubescens)

ABSTRACT The effects of Copper (Cu) on growth of Moso bamboo (Phyllostachys heterocycla (Carr.) Mitford cv. pubescens) were investigated. The dry weight of Moso bamboo was inhibited and significant differences were evident under Cu stress as compared to the control (CK). Solution culture experiments indicated that Moso bamboo had a strong ability to accumulate Cu in shoots. Copper accumulation in the stem was stronger than the leaves; the stem/root ratio could reach 0.20 under Cu stress. The changes in cell walls, stomata, vacuoles, and starch grains content were observed via scanning electron microscopy and transmission electron microscopy. The ultrastructural analysis revealed that the excessive Cu concentrations caused deformities in the chloroplasts and transformation and even disappearance of endoplasmic reticulum. Moso bamboo as an experimental material serves as a new tool for remediation of heavy metal contaminated soils due to its metal tolerance and excessive biomass production.