镉富集植物镉积累基因型差异及分子机理研究

发布时间：2018-06-28 22:44

本文选题：镉 + 植物修复　；参考：《西南大学》2017年硕士论文

【摘要】：近年来,随着城市化、工业化和农业化的集约发展,规模的不断扩大,工业“三废”排放、化肥农药滥用、污水灌溉及城镇污泥的使用等,使得土壤镉含量日益增加,土壤镉污染问题日趋严重。如何治理和修复土壤镉污染备受关注。植物修复技术作为一种新兴的绿色生物技术,具有操作简单、经济及技术上能够大面积实施等优点,被认为是修复重金属污染土壤的最佳选择。黑麦草(Lolium multiflorum L.)一年生或短期多年生,生物量大,对土壤重金属有极强的富集作用,同时生长迅速、分蘖能力强,可以快速覆盖地面;印度芥菜(Brassica juncea L.)为十字花科芸薹属植物,其生长周期短、地上部生物量大、可富集多种重金属,在植物修复中有较大的应用潜力;紫花苜蓿(Medicago Sativa L.)为豆科多年生草本植物,是一种高产出的经济作物,其对Cd离子也具有较高的富集作用。目前有关黑麦草、紫花苜蓿及印度芥菜对镉吸收能力的比较以及相关植物耐镉基因等分子机理层面的研究较少。因此,本试验以黑麦草(品种为邦德和阿伯德)、印度芥菜及紫花苜蓿为试验材料,通过土培试验模拟矿区土壤Cd污染水平(0、75、150、300及600 mg·kg~(-1)),研究不同镉富集植物在不同镉污染水平土壤上生长、抗氧化酶活性、Cd含量及积累量的差异,探求不同植物的最大Cd吸收值,以及通过RT-PCR观察镉抗性基因表达情况,从分子机理层面解释植株富集重金属机制,以期为土壤Cd污染的合理防治和修复提供理论依据。主要研究结果如下:(1)黑麦草(邦德和阿伯德)地上部干重及植株总干重随土壤镉污染水平的增加表现为先增加后减少趋势。75 mg·kg~(-1)Cd、150 mg·kg~(-1)Cd分别刺激了黑麦草(邦德)、黑麦草(阿伯德)生长,其地上部干重较对照分别增加10.06%和25.84%。各镉处理下,黑麦草(邦德和阿伯德)地上部干重远高于印度芥菜和紫花苜蓿。(2)在不同镉污染水平下,3种镉富集植物光合系统参数均受到显著抑制。随土壤镉水平增加,3种镉富集的MDA含量呈下降趋势,当外源镉水平为600 mg·kg~(-1)时,黑麦草(邦德和阿伯德)、紫花苜蓿及印度芥菜根系MDA含量均显著低于对照(P0.05),分别较对照降低了49.62%、44.44%、40.74%及51.68%。随镉胁迫增加,SOD、POD总体呈先升高后降低的趋势,CAT则呈降低趋势。(3)黑麦草(邦德和阿伯德)、紫花苜蓿及印度芥菜对镉均具有较强的富集能力,各部位镉含量均为根系地上部。且在150 mg·kg~(-1)、75 mg·kg~(-1)Cd水平下,黑麦草(邦德和阿伯德)、紫花苜蓿和印度芥菜地上部镉含量分别为171.827 mg·kg~(-1)和169.122 mg·kg~(-1)、356.463 mg·kg~(-1)和308.735 mg·kg~(-1),均超过超富集植物临界值(100 mg·kg~(-1)),表现出极强的超富集潜力。(4)在75 mg·kg~(-1)Cd时以黑麦草(阿伯德)的土壤镉去除率最佳,为16.24%,其他镉水平下,均以紫花苜蓿对土壤镉去除率最佳,分别为19.82%、30.72%和26.78%。综合考虑积累量及土壤镉去除率等因素,可以采用多种植物轮作方式提高土壤Cd的整体去除率。(5)在各Cd污染水平下,土壤镉均主要以EXC-Cd存在,FDC高达55.09%~83.23%。各形态Cd FDC大小顺序为:EXC-CdCAB-CdFeMn-CdRES-CdOM-Cd。随着土壤镉水平的增加,EXC-Cd的FDC不断增加。土壤各镉形态中,除OM-Cd外,其余土壤镉形态与植株地上及根系镉含量均呈极显著正相关(P0.01)。(6)供试3种植物材料,黑麦草(品种为邦德和阿伯德)、紫花苜蓿及印度芥菜的BCF均大于1,且印度芥菜紫花苜蓿黑麦草(阿伯德)黑麦草(邦德),印度芥菜对镉的富集能力最强。所有处理TF值均小于1,大小顺序为黑麦草(阿伯德)黑麦草(邦德)紫花苜蓿印度芥菜,黑麦草(阿伯德)能最有效聚集土壤中的镉。(7)外源镉诱导黑麦草(邦德和阿伯德)2个镉代谢相关的基因(家族)OAS和IRT表达水平在不同镉水平间的变化趋势差异显著;相同物种不同亚种间也存在很大差异。黑麦草(邦德)OAS和IRT基因(家族)表达对镉处理较敏感,在75 mg·kg~(-1)Cd时即出现显著上调;黑麦草(阿伯德)OAS和IRT基因(家族)总体在150 mg·kg~(-1)镉水平时出现显著上调,且上调幅度均显著低于黑麦草(邦德)。同一家族内部的不同成员基因在同一植株的反应趋势相同。
[Abstract]:In recent years, with the intensive development of urbanization, industrialization and agriculture, the expansion of the scale, the emission of industrial "three wastes", the abuse of chemical fertilizers and pesticides, the irrigation of sewage and the use of municipal sludge, the cadmium content in soil is increasing, and the problem of soil cadmium pollution is becoming more and more serious. As a new green biological technology, it has the advantages of simple operation and large area implementation in economy and technology. It is considered to be the best choice for remediation of heavy metal contaminated soil. Lolium multiflorum L. (ryegrass) is an annual or short term perennial with a large biomass, strong enrichment to heavy metals in soil and growth of heavy metals. India mustard (Brassica juncea L.) is a Brassica plant of the family Cruciferae, which is fast and capable of high tillering ability. Its growth cycle is short, the biomass of the upper part of the ground is large, it can enrich a variety of heavy metals and has great potential for application in phytoremediation. Alfalfa (Medicago Sativa L.) is a kind of perennial legume herbaceous plant, which is a kind of high yield. At present, there are few studies on the cadmium absorption capacity of ryegrass, alfalfa and India mustard, as well as the molecular mechanism level of cadmium resistance genes in the related plants. Therefore, the test is made of ryegrass (breeds for Bond and albad), India mustard and alfalfa as a test. Through soil culture test, the soil Cd pollution level (0,75150300 and 600 mg kg~ (-1)) was simulated by soil culture test. The difference in the growth of different cadmium enriched plants, the activity of antioxidant enzymes, the difference of Cd content and accumulation, the maximum Cd absorption value of different plants, and the expression of cadmium resistance gene through RT-PCR were studied. In order to provide theoretical basis for rational control and restoration of soil Cd pollution from the molecular mechanism, the main results are as follows: (1) the dry weight of ryegrass (Bond and arbor) and the increase of total dry weight of plant with the increase of soil cadmium pollution level first and then decrease the trend of.75 mg. Kg~ (-1) Cd, 150 Mg. Kg~ (-1) Cd stimulated ryegrass (Bond) and ryegrass (albad) to grow. The dry weight of the upper ground was 10.06% and 25.84%. respectively. The dry weight of ryegrass (Bond and albad) was much higher than that of India mustard and alfalfa. (2) the photosynthetic system parameters of 3 cadmium enriched plants were all under different levels of cadmium pollution. The content of 3 cadmium enriched MDA decreased with the increase of cadmium level in soil. When exogenous cadmium level was 600 mg. Kg~ (-1), the MDA content of ryegrass (Bond and albad), alfalfa and India mustard root were significantly lower than those of control (P0.05), which decreased by 49.62%, 44.44%, 40.74% and 51.68%., respectively, with cadmium stress, respectively. SOD, POD overall increased first and then decreased, and CAT decreased. (3) ryegrass (Bond and albad), alfalfa and India mustard have strong enrichment ability to cadmium, and the content of cadmium in all parts of root is above ground. And at the level of 150 mg. Kg~ (-1), 75 mg. Kg~ (-1) Cd, ryegrass (Bond and albad), alfalfa and India. The content of cadmium in the ground mustard was 171.827 mg. Kg~ (-1) and 169.122 mg. Kg~ (-1), 356.463 mg. Kg~ (-1) and 308.735 mg. Kg~ (-1), which were above the critical value of the hyperconcentration plant (100). (4) the best removal rate of cadmium in the soil of ryegrass (Arbor) was 16.24%, and the other was 16.24%. The removal rate of cadmium in soil was the best under the level of Alfalfa at the level of cadmium, which was 19.82%, 30.72% and 26.78%., considering the accumulation of soil and the removal rate of cadmium in soil. The overall removal rate of soil Cd could be improved by a variety of plant rotation methods. (5) under the level of Cd pollution, the soil cadmium was mainly EXC-Cd and FDC was as high as 55.09%~83.23%.. The order of the size of Cd FDC was as follows: EXC-CdCAB-CdFeMn-CdRES-CdOM-Cd. increased with the increase of soil cadmium level and the FDC of EXC-Cd. Except OM-Cd, the cadmium speciation of the other soil was significantly positively correlated with the CD content of plant and root (P0.01). (6) 3 species of plant materials, ryegrass (Bond and arbor), were tested. The BCF of alfalfa and India mustard were more than 1, and India mustard alfalfa (alfalfa) ryegrass (albad) ryegrass (bond) and India mustard had the strongest enrichment ability to cadmium. All treatment TF values were less than 1, the size order was ryegrass (A Bode) alfalfa India mustard, and ryegrass (albad) was the most effective gathering soil. (7) the variation trend of OAS and IRT expression levels of 2 cadmium related genes (family) related genes (family) of ryegrass (Bond and arbor) in ryegrass (Bond and arbor) was significant difference between different cadmium levels, and there were significant differences among the same species. The expression of ryegrass (Bond) OAS and IRT gene (family) was more sensitive to cadmium treatment, and in 75 mg. Kg~ (-1) Cd The OAS and IRT gene (family) increased significantly at 150 mg. Kg~ (-1) levels, and the up-regulated range was significantly lower than that of ryegrass (bond). The same gene in the same family was the same in the same family.
【学位授予单位】：西南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X53;X173

【参考文献】