不同大气环境中白皮松针叶重金属积累及抗性特征研究

为了解白皮松(Pinus bungeana Zucc.)针叶在不同大气环境中对重金属的积累状况和抗性特征,分别测定了城区、郊区和山区的白皮松当年生、二年生和三年生针叶中Cu、Mn、Zn和Cd的含量,比较了3种年龄针叶中超氧化物歧化酶(SOD)活性以及丙二醛(MDA)、可溶性蛋白、可溶性糖和游离脯氨酸含量。结果表明:在不同采样点,白皮松针叶中的Cu、Mn、Zn和Cd的含量表现为城区郊区山区;在不同年龄间,Cu、Mn和Cd的含量在山区表现为三年生二年生当年生,而在城区、郊区和山区Zn的含量则随着针叶年龄的增加而降低。采样点对针叶中Cu、Zn和Cd的含量影响较大,而针叶年龄对Mn的影响较大。针叶中重金属含量的增加促进了MDA、可溶性糖、可溶性蛋白和游离脯氨酸含量的积累。随着针叶年龄的增加,白皮松针叶SOD活性呈现下降趋势,并在山区最低;山区当年生白皮松针叶SOD活性显著低于郊区和城区。相关性分析表明,可溶性蛋白、可溶性糖和游离脯氨酸与4种重金属呈显著或极显著正相关。综上表明,白皮松三年生针叶对于大气重金属污染具有监测价值;针叶中可溶性蛋白、可溶性糖和游离脯氨酸对重金属造成的氧化胁迫具有指示作用;白皮松积累可溶性蛋白、可溶性糖和游离脯氨酸可能是其抵御重金属胁迫的一种适应机制。

Study on resistance characteristics to heavy metal accumulation of Pinus bungeana Zucc. needles from different atmospheric environments

The purpose of this study was to determine the contents of Cu, Mn, Zn, and Cd in current-year(C), 2-year old(C+1), and 3-year old(C+2) needles of Pinus bungeana Zucc. from urban, suburban, and rural areas. Analysis also concerned resistance indices including superoxide dismutase(SOD) activity and the malondialdehyde(MDA), soluble protein, soluble sugar, and free proline contents in needles. Results showed that the urban area had the highest accumulation of Cu, Mn, Zn, and Cd in needles of the same age from different sites. Accumulation of Cu, Mn, and Cd increased with age for needles from the rural area whereas that of Zn decreased with needle age for all three sites. Meanwhile, two-way analysis of variance(ANOVA) was used to evaluate the interactions between sampling site and plant species and showed that the sampling site played a greater role than needle age for Cu, Zn, and Cd, whereas for Mn, the effect of needle age was greater than that of the sampling site. MDA, soluble protein, soluble sugar, and free proline contents in the needles were elevated because of increasing heavy metal accumulation. SOD activity decreased with age and was the lowest in the rural area. Correlation analysis showed that the Cu, Mn, Zn, and Cd contents had a significant or extremely significant positive correlation with the soluble protein, soluble sugar, and free proline contents in the needles. In conclusion, the 3-year old needles of P. bungeana are considered suitable biomonitors for heavy metal pollution in the environment. The soluble protein, soluble sugar, and free proline contents in the needles seem to be good indications for the oxidative stress caused by heavy metals and may be involved in an adaptation mechanism to external stress.