耐镉植物抗性及富集规律的研究

发布时间：2018-05-14 21:12

本文选题：多花黑麦草 + 孔雀草　；参考：《贵州大学》2015年硕士论文

【摘要】：随着工业化的不断扩张、农业中化肥、农药、除草剂的广泛使用及矿山开采造成的污染日益威胁人们的生活和健康,土壤镉(Cd)污染已经成为全球最严重的环境问题之一。很多国家对土壤重金属污染非常重视,采取了多种修复方法,其中植物修复已成为世界各国争相研究的热点,植物修复利用绿色植物的新陈代谢活动来提取、降解、固定或挥发污染土壤环境中的重金属污染物,是一种非常绿色环保的修复技术,不仅保持污染现场土壤的结构,也可减少修复费用。本研究以草本植物多花黑麦草(Lolium multiflorum L.)和孔雀草(Tagetes patula L.)为试验材料,通过盆栽试验,研究不同梯度Cd胁迫对其种子萌发及幼苗期间生长、成年植株生理抗逆性、Cd积累特性及叶片超微结构的影响,以期挖掘出具有修复潜力的植物。研究结果如下:(1)多花黑麦草和孔雀草种子的萌发对Cd胁迫生理响应程度不同,高浓度Cd胁迫会抑制植物的发芽指数和活力指数,各处理间的活力指数随Cd胁迫浓度的增加而显著降低(P0.05)。两者的根长和苗长随Cd胁迫浓度的增加均逐渐缩短,在500 mg.L-1Cd胁迫下,两者的根长比对照分别显著降低了92.00%、92.03%,两者的苗长分别比对照显著降低了40.00%、55.68%,可见高浓度Cd胁迫对根的抑制作用尤为显著。此外,随Cd胁迫浓度的增加,两者的CAT活性均先升后降;多花黑麦草的SOD活性先升后降、孔雀草的SOD活性先降后生再降,在100 mg.L-1Cd胁迫下多花黑麦草SOD的活性最大(150.26 U.g-1.min Fw),而孔雀草的SOD活性达到最大(149.83 U.g-1.min Fw)时的胁迫浓度为400mg.L-1。两者的POD活性均表现为先升后降。可见2种植物幼苗的抗氧化系统对Cd胁迫产生不同程度的生理响应,在一定浓度Cd胁迫范围内,植株可以通过提高自身体内抗氧化酶的活性来清除自由基积累造成的伤害,而Cd胁迫浓度超过一定阈值,植物体内的抗氧化酶活性降低,植物的耐受性降低。(2)Cd是植物光合作用的抑制剂,高浓度Cd(300 mg.kg-1)胁迫均可抑制多花黑麦草和孔雀草叶绿素的合成。随Cd胁迫浓度的增加,2种植物的Fo先降后升;Fm、Fv/Fm和Fv/Fo先升后降。同时多花黑麦草叶片的ФPSⅡ、ETR、qP和qN均先升后降;孔雀草的ФPSⅡ、ETR、qP大体上是先升后降、qN大体上是升高的。可见高浓度Cd胁迫均能够使2种草本植物叶片PSⅡ反应中心受损,降低电子传递能力和光化学效率,影响及扰乱植物生长期间的光合特性。(3)Cd胁迫同样影响2种草本植物成年植株的抗氧化系统,随Cd胁迫浓度的增加,多花黑麦草的CAT活性先降后升,孔雀草的CAT活性先升后降,多花黑麦草和孔雀草的CAT活性达到最高的Cd浓度分别为300 mg.kg-1和50 mg.kg-1;多花黑麦草的SOD活性先升后降,在100 mg.kg-1Cd胁迫下的SOD活性最大(138.31 U.g-1.min-1Fw);孔雀草的SOD活性先降后生再降,在200 mg.kg-1Cd胁迫下的SOD活性最大(123.18 U.g-1.min-1Fw);两者的POD活性均先升后降,两种植物的POD活性达到最高的Cd浓度分别为200、50 mg.kg-1;两者的脯氨酸和MDA含量存在差异,高浓度Cd(300 mg.kg-1)下孔雀草脯氨酸含量(15.40 ug.g-1 Fw)和MDA含量(6.88 nmol.g-1 Fw)显著高于多花黑麦草(1.97 ug.g-1 Fw、6.1 nmol.g-1 Fw)。可见,不同植物对Cd胁迫表现出不同的生理抗逆性。(4)多花黑麦草和孔雀草地上部和地下部Cd含量随Cd胁迫浓度的增加而逐渐升高,各处理间多花黑麦草组织内Cd分布特征均表现为:地下部地上部,转运系数降低。在50mg.kg-1Cd浓度胁迫下,孔雀草根、茎和叶中Cd积累量分布特征表现:叶茎根,根-茎转运系数(1.33)1,在300 mg.kg-1Cd浓度胁迫下,地上部Cd含量(135 mg.kg-1)已超过Cd超富集植物的临界值,且孔雀草植株生长过程中没有出现明显的毒害症状,由此可知,孔雀草是Cd超富集的特征植物。(5)多花黑麦草和孔雀草的叶片超微结构在高浓度Cd(300 mg.kg-1)胁迫下发生不同程度的损伤。其中多花黑麦草叶肉中部分叶绿体膨胀成球形,基粒紊乱、基质片层结构溶解,嗜锇颗粒增多,且出现相互聚集的现象,但大部分叶绿体内部结构还是正常的。而孔雀草叶绿体数量明显减少,基粒及基质片层几乎看不清,同时叶绿体中出现巨型淀粉粒,嗜锇颗粒增大,线粒体数目减少甚至消失。同时发现,相同植物不同细胞中的相同细胞器受Cd胁迫损伤程度存在差异。
[Abstract]:With the continuous expansion of industrialization, the widespread use of chemical fertilizers, pesticides, herbicides and the pollution caused by mining are increasingly threatening people's life and health. The pollution of soil cadmium (Cd) has become one of the most serious environmental problems in the world. Many countries attach great importance to the pollution of soil heavy metals, and adopt a variety of remediation methods. Phytoremediation has become a hot spot in the world. Phytoremediation uses the metabolic activity of green plants to extract, degrade, fixed or volatilize the heavy metal pollutants in the soil environment. It is a very green environmental remediation technology, which not only maintains the soil structure of the contaminated site, but also reduces the cost of restoration. Herbaceous plants (Lolium multiflorum L.) and peacock grass (Tagetes patula L.) were tested as experimental materials. Through pot experiments, the effects of different gradient Cd stresses on Seed Germination and seedling growth, physiological resistance of adult plants, the accumulation of Cd and the ultrastructure of leaves were studied in order to excavate the plants with potential for restoration. The results were as follows: (1) the germination of the seeds of ryegrass and peacock grass had different physiological responses to Cd stress. High concentration of Cd stress could inhibit the germination index and vigor index of plants, and the vigor index of each treatment decreased significantly with the increase of Cd stress (P0.05). The root length and seedling length of both of them gradually increased with the increase of the concentration of Cd stress. Under the stress of 500 mg.L-1Cd, the root length of both of them decreased by 92%, 92.03% respectively, and the seedling length of both of them was significantly lower than the control by 40%, 55.68%, and the inhibitory effect of high concentration Cd stress on the root was particularly significant. In addition, the CAT activity of both of them increased first and then decreased with the increase of Cd stress, and the SOD activity of ryegrass was SOD. The SOD activity of the peacock grass decreased first and then descended, and the activity of SOD in ryegrass was the largest (150.26 U.g-1.min Fw) under 100 mg.L-1Cd stress, while the SOD activity of the peacock grass reached the maximum (149.83 U.g-1.min Fw) and the POD activity of both of them was first rising and then decreasing. The antioxidant activity of 2 plant seedlings was visible. The physiological response of the system to Cd stress is different. In a certain concentration of Cd stress, the plant can remove the damage caused by the free radical accumulation by improving the activity of antioxidant enzymes in the body, while the Cd stress concentration exceeds a certain threshold, the antioxidant enzyme activity in the plant is reduced and the plant tolerance is reduced. (2) Cd is the plant. Photosynthesis inhibitor, high concentration Cd (300 mg.kg-1) stress can inhibit the synthesis of chlorophyll of ryegrass and peacock grass. With the increase of Cd stress, the Fo of the 2 plants first descends and then rises, Fm, Fv/Fm and Fv/Fo first rise and then descend. It was first raised and then descended, and qN was generally elevated. It was found that high concentration of Cd stress could damage the PS II reaction center of the leaves of 2 herbaceous plants, reduce the electron transfer ability and photochemical efficiency, and disturb the photosynthetic characteristics during plant growth. (3) Cd stress also affects the antioxidant system of the 2 plants of the plant, with the concentration of Cd stress. The CAT activity of Lolium multiflorum increased first and then increased, and the CAT activity of peacock grass first increased and then decreased. The CAT activity of ryegrass and peacock grass reached the highest Cd concentration of 300 mg.kg-1 and 50 mg.kg-1 respectively. The SOD activity of ryegrass was first increased and then decreased, and the maximum SOD activity under 100 mg.kg-1Cd stress (138.31 U.g-1.min-1Fw); peacock grass. The activity of SOD first descended and then descended, and the activity of SOD was the maximum (123.18 U.g-1.min-1Fw) under 200 mg.kg-1Cd stress, and the POD activity of both of them increased first and then decreased, and the highest POD activity of the two plants was 200,50 mg.kg-1, respectively, and the proline and MDA content of both of the two was different, and the proline content of peacock grass under the high concentration Cd (300 mg.kg-1) was 15. The content of.40 ug.g-1 Fw) and MDA (6.88 nmol.g-1 Fw) was significantly higher than that of Lolium multiflorum (1.97 ug.g-1 Fw, 6.1 nmol.g-1 Fw). It can be seen that different plants showed different physiological stress resistance to Cd stress. (4) the Cd content in the upper and underground meadows of ryegrass and peacock increased with the increase of coerced concentration. The distribution characteristics of Cd in the weave were all: the transport coefficient of the upper part of the ground was reduced. The distribution characteristics of Cd accumulation in the root, stem and leaf of the peacock were characterized by 50mg.kg-1Cd concentration stress: the leaf stem root, the root and stem transport coefficient (1.33) 1, and the Cd content in the upper part of the ground (135 mg.kg-1) under the stress of 300 mg.kg-1Cd, which had exceeded the critical value of the Cd hyperconcentration plant. There are no obvious toxic symptoms in the growth process of the plants of the peacock grass. Thus, it is known that the peacock grass is a characteristic plant of Cd superconcentration. (5) the ultrastructure of the leaves of ryegrass and peacock grass have different degrees of damage under the stress of high concentration of Cd (300 mg.kg-1). The structure of the stroma layer dissolves, the osmium granules increase and the osmium particles increase, and the internal structure of most chloroplasts is normal, but the number of chloroplasts in the chloroplasts is obviously reduced, the grana and the matrix layer are almost invisible, and the chloroplasts appear in the giant amylin particles, the osmium particles increase, the number of mitochondria decreases or even disappear. Meanwhile, it was found that the same organelles in different cells of the same plant were damaged by Cd stress.

【学位授予单位】：贵州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X173;X53

【参考文献】