紫花苜蓿对铜胁迫生理响应的傅里叶变换红外光谱法研究  

Physiological response of Medicago sativa L.to copper stress by FTIR spectroscopy

作　　者：付川[1] 余顺慧[1] 黄怡民[1] 邓洪平[2] 

机构地区：[1]重庆三峡学院,三峡库区水环境演变与污染防治重庆高校市级重点实验室,重庆404100 [2]西南大学生命科学学院,三峡库区生态环境教育部重点实验室,重庆400715

出　　处：《生态学报》2014年第5期1149-1155,共7页Acta Ecologica Sinica

基　　金：三峡库区水环境演变与污染防治重庆高校市级重点实验室开放基金项目(WEPKL2012MS-01)

摘　　要：为阐明紫花苜蓿(Medicago sativa L.)对铜胁迫的耐性机理,采用准确度好、分辨率高和简便快捷的傅里叶变换红外光谱法(FTIR)研究在不同铜浓度(0、1、5、20、100 mol/L)处理时紫花苜蓿根、茎、叶化学组分的变化。结果表明:随着铜处理浓度的增加,紫花苜蓿根、茎、叶生物量变化不大。其根组织在2924 cm^(-1)处峰高处呈现出先下降后上升的趋势,反映了在低铜(<5 mol/L)处理条件下紫花苜蓿分泌的有机酸不断螯合Cu,造成羧酸0-H的减少,但随着Cu含量的升高,其羧酸螯合力变弱,有机酸含量渐渐升高;根组织在1381 cm^(-1)处峰高先下降后上升,反映了含油脂化合物含量先下降后升高。可能与植物在细胞壁结构上增强抗逆性有一定关系,即低Cu处理下细胞壁可能通过提高阳离子交换能力(CEC),增强了耐Cu性;茎组织在2924,1643,1381,1064 cm^(-1)等处峰高无明显变化;叶组织所有峰值在低浓度(<5 mol/L)Cu处理下变化不明显,高浓度(>5 moL/L)Cu处理下所有峰值先升后降,随着这可能与可溶性糖及可溶性蛋白质等物质含量都呈现先升后降的趋势有关。这表明紫花苜蓿通过根部有机酸含量的变化和提高细胞壁阳离子交换能力,将吸收的Cu大部分积累在根部,阻止Cu向地上部分运输,有效地保护了植物地上部分组织。Although copper （Cu） is required for plant growth and development, excessive levels of this element can be toxic to plants. Soil pollution and degradation take place when Cu is released into the environment through activities such as mining, discharge of ＂ three wastes＂ （ i.e., waste water, waste gas, and waste residue ） , and application of cupric fungicides. Medicago sativa, a perennial flowering plant native to Iran, has been cultivated as an important forage crop in many countries around the world. This species is reported to be a copper-hyperaccumulator, and studies suggest that it may be useful for phytoremediation. To elucidate the mechanism of copper tolerance in M. sativa, changes in levels of chemical constituents of M. sativa treated with different concentrations of Cu solution were investigated using Fourier transform infrared spectroscopy （FTIR）, an accurate, simple, efficient technique with high resolution. After germination in a seed tray, M. sativa seedlings of uniform size and appearance were selected and transplanted into a hydroponics system. After pre-euhivation with one-quarter strength Hoagland＇s solution for one week, the seedlings were treated with different concentrations of Cu^2＋, i.e., 0, 1, 5, 20, and 100 mol/L. After 45 days of treatment with Cu^2＋ solution, roots, stems, and leaves were separated and dried to measure biomass and to detect changes in chemical constituent levels. Although root, stem, and leaf biomass of M. sativa decreased slightly as concentrations of Cu^2＋ were increased, these changes were not found to be significant. After an initial decline, absorbance in roots of the dominant infrared band near 2924 cm^-1 exhibited an increasing trend. This result indicates that at low Cu2＋concentrations （ 〈5 mol/L）, organic acids secreted by M. sativa were able to chelate Cu^2＋ , leading to a decrease in carboxylic acid O-H; at high Cu^2＋ concentrations （ 〉5 mol/L）, chelating activity decreased, which was followed by an increase in orga

关 键 词：紫花苜蓿 铜胁迫 化学组分 傅里叶变换红外光谱法(FTIR) 

分 类 号：S541.1[农业科学—作物学]