【作者】 雷蕾；

【导师】 范稚莲；

【作者基本信息】 广西大学 ， 土壤学， 2018， 硕士

【摘要】 锑（Sb）在环境中普遍存在,过量的Sb会对人体和植物产生毒害。近年来,我国环境中Sb污染问题日益受到人们的关注。水稻是我国重要粮食作物,也是易富集Sb的一种农作物。稻米中Sb富集的报道也常见于媒体报道中。因此,研究Sb对水稻的毒害作用机制,及不同形态Sb在水稻体内吸收、转运、形态转化过程可为解决稻米中Sb富集问题提供理论支持。本文通过水培试验,以水稻（野香优3号）为试验材料,研究不同形态Sb对水稻的毒害作用以及水稻缓解Sb毒害的策略。取得的主要结果有:（1）研究了不同形态Sb对水稻生长及根系发育的影响。结果表明:不同形态Sb对水稻的生长及根系发育的影响不同。Sb（Ⅲ）对水稻的毒害作用要强于Sb（Ⅴ）,具体表现为:Sb（Ⅲ）处理下水稻地上和根系生物量一般小于Sb（Ⅴ）处理下;20mg·L^-1Sb（Ⅲ）处理抑制了大多数根系形态特征参数,包括根长、根体积、根表面积、根尖数和根分叉数;而20mg·L^-1 Sb（Ⅴ）仅降低了水稻根面积、根直径和分叉数;Sb（Ⅲ）处理增加了水稻根系粗根和中等根比例,降低了细根比例;而随Sb（Ⅴ）处理降低了粗根和中等根比例,增加了细根比例。（2）研究了水稻对Sb及必需营养元素的吸收、转运及亚细胞分布,以及Sb在水稻体内的形态转化。研究结果发现:1)Sb（Ⅲ）处理下水稻吸收Sb的能力较Sb（Ⅴ）处理时的强;两种形态Sb处理下水稻向地上部分转运Sb的能力均较弱,大部分吸收的Sb富集在其根部;2)Sb（Ⅲ）处理下,水稻根系和地上部分Sb的形态主要以Sb（Ⅲ）为主;而Sb（V）处理下,水稻根系和地上部分Sb的形态主要以Sb（V）为主,表明水稻对不同形态Sb的转化能力较弱;3)Sb（Ⅲ）处理显著增加了水稻地上部分Mg、K、Ca、Fe、Cu、Zn的含量;而在Sb（V）处理下,仅10 mg·L^-1处理浓度显著增加了大部分必需营养元素的含量,如Mg、K、Ca、Mn、Fe、Cu;4)Sb（V）处理显著增加了水稻伤流液的数量,增加了伤流液中Fe、Cu的含量;而Sb（Ⅲ）未显著影响伤流液的量,但部分处理水平显著增加了伤流液中Fe、Cu、Sb的含量;伤流液中Ca的含量在两种形态Sb处理下均降低;5)不同形态Sb处理下,细胞壁和细胞液均富集了绝大部分Sb,表明细胞壁和细胞液在抑制Sb吸收方面起到重要作用;在Sb（Ⅲ）处理下,细胞壁和细胞液束缚Sb的能力随着Sb处理浓度的增加而降低,但在Sb（V）处理下细胞壁起到越来越重要的作用;细胞器Mg、K、Fe、Zn和Cu含量占比在大部分Sb（Ⅲ）和Sb（V）处理下均增加,而细胞壁组分中Ca含量占比增加,显示上述元素在抵御Sb胁迫过程中起到一定作用。（3）研究了水稻体内抗氧化系统对不同形态Sb胁迫的响应,结果发现:1)两种形态Sb均对水稻产生氧化胁迫,而Sb（Ⅲ）处理较Sb（V）明显增加了根系MDA含量;2)SOD和APX被不同形态Sb处理激活,表明其在缓解Sb胁迫过程中起到一定作用;而大部分不同形态Sb处理均显著抑制POD活性,表明POD在缓解Sb胁迫过程中所起作用有限。（4）研究了根系细胞壁组分、根系分泌物以及根系内源激素对不同形态Sb胁迫的响应,以期揭示上述物质与Sb吸收、毒性缓解方面的作用机制。研究结果表明:1)不同形态Sb处理下,水稻根系中果胶和木质素含量均显著增加,而半纤维素Ⅰ和半纤维素Ⅱ含量基本未增加,表明果胶和木质素在降低Sb吸收或抵御Sb胁迫过程中起到重要作用;2)大部分不同形态Sb处理均显著增加了根系分泌草酸的量,降低了甲酸和乙酸的分泌量,表明草酸在Sb吸收过程中可能存在一定作用;3)Sb（Ⅲ）处理显著增加了根系脱落酸（ABA）的含量,而Sb（V）处理基本未显著影响根系ABA的含量,表明Sb（Ⅲ）胁迫下,水稻根系分泌了大量ABA,促进了细胞老化过程;不同形态Sb处理对水杨酸（SA）含量基本未有显著影响（尽管大部分处理不显著增加了 SA含量）,表明SA在抵御不同形态Sb胁迫过程中所起作用有限。更多还原

【Abstract】 Antimony（Sb）extensively distributes in the environment and excess of Sb is harmful to humans and plants.In recent years,the issues of Sb pollution in soil environment in China’s have increasingly attracted people’s attention.Rice plant is an important food crop in China,and can easily enrich a large amount of Sb.Many media reports have shown increasing incidents of Sb pollution in the grains of rice plants.Therefore,it seems to be vital to investigate the mechanisms on the toxicity,uptake,translocation and speciation transformation of different forms of antimony（Sb）in plants,which can give the theory supporting for dealing with the excess accumulation of Sb in rice grains.In this paper,we conducted three related experiments in hydroponic culture system using a rice variation named Yoshihikari No.3 to resolve below questions:1)the effects of different forms of Sb[Sb（Ⅲ）and Sb（Ⅴ）]on the growth of rice plants and root morphology changes;2)the effects of Sb（Ⅲ）and Sb（Ⅴ）on the uptake,translocation and subcellular distribution of Sb and essential elements;3)the transformation of different forms of Sb in different tissues of rice plants;4)the production of bleeding sap and the concentrations of its containing elements;5)the responses of antioxidative systems to different forms of Sb;6)the roles of root exudates,components of root cell wall and endogenous hormones in alleviating the toxicity of different forms of Sb.The main results are as follows:（1）The effects of different forms of Sb on the growth of rice plants and on the root development were studied.The results shows that the effects of different forms of Sb on the the growth of rice plants and on the root development are different.The toxicity of Sb（III）is higher than that of Sb（V）,showing as the lower biomass of shoots and roots of rice plants exposing to Sb（Ⅲ）than exposing to Sb（V）;The addition of 20 mg·L^-1 Sb（Ⅲ）inhibited the most of tested parameters of root morphology including root length,root volume,root surface area,root tips and root forks;however,20 mg·L^-1 Sb（V）only significantly reduced the root surface area,root diameter and root forks.The treatments containing Sb（III）increased the proportions of coarse and medium roots,but reduced the fine root proportion;however,the addition of Sb（V）reduced the coarse and medium root proportions but increased the fine root proportion.（2）The effects of different forms of Sb on the uptake,translocation and subcellular distribution of Sb and essential elements were studied.The speciation transformation of Sb in different tissues of rice plants was also monitored.The results shows that:1)the rice plants show a stronger ability to take up Sb upon exposure to Sb（III）than upon exposure to Sb（V）.The rice plants do not have a strong ability to translocate the absorbed Sb from the roots to shoots,and most Sb in rice plants are concented in the roots of rice plants;2)Sb（III）is the main speciation when the plants is subjected to Sb（III）exposure,but Sb（V）is the main speciation under Sb（V）stress,suggesting a weak ability of rice plants to transform different forms of Sb;3)in most cases the addition of Sb（III）sigficantly increased the concentrations of some essential elements in the shoots of rice plants,including Mg,K,Ca,Fe,Cu and Zn.However,only 10 mg·L^-1 Sb（V）significantly enhanced the uptake of Mg,K,Ca,Mn,Fe and Cu in the shoots of rice plants exposing to Sb（V）;4)the addition of Sb（V）significantly enhanced the production of bleeding saps with increased Fe and Cu concentrations and a decreased Ca concentration;However Sb（Ⅲ）showed a limited effect on the production of bleeding saps but increased the Fe,Cu and Sb concentrations and a decreased the Ca concentration in the bleeding saps;5)the cell wall and cell cytosol sequested most of Sb in the shoots and roots,suggesting the important roles of them in inhibiting Sb uptake.Under Sb（III）exposure,the ability of cell wall and cell cytosol to restrain Sb became weak along with the increasing Sb exposing levels.However,the cell wall play an increasingly role in constraining the Sb when plants were subjected to Sb（V）.The addition of Sb（III）and Sb（V）resulted in more translocations of Mg,K,Fe,Zn and Cu from other subcellular components to cell organelles,and more accumulation of Ca in cell wall,suggesting the important roles of these elements in alleviating the toxicity of different Sb.（3）The responses of antioxidative systems to the stress of different forms of Sb stress was studied.The results show that:1)the addition of different forms of Sb both produced oxidative stress to rice plants,significantly enhancing the contents of MDA in the shoots and roots.The Sb（Ⅲ）showed a higher ability to increase the content of MDA than Sb（V）;2)the enzymes like SOD and APX were activated,showing a potential role in controlling the ROS;however,most treatment containing Sb（Ⅲ）and Sb（V）significantly reduced the activity of POD enzyme,indicating a limited role in quenching the H2O2.（4）The effects of different forms of Sb on the concentrations of cell wall components,root exudates and endogenous hormones were also evaluated.The results show that:1)the addition of different fornms of Sb significantly increased the contents of pectin and lignin,but did not significantly affect the contents of hemicelluloses I and hemicelluloses II in the roots of rice plants.Above results indicate that pectin and lignin of rice root cell wall might play roles in restraining Sb uptake;2)the concentration of oxalic acid was significantly enhanced by Sb（Ⅲ）and Sb（V）,but the concentrations of formic acid and acetic acid were significantly decreased by Sb（Ⅲ）and Sb（Ⅴ）.Above results suggested that oxalic acid might play a role in regulate the uptake of Sb.3)The addition of Sb（III）significantly stimulated the formation of abscisic acid（ABA）but Sb（V）showed a non-significant effects on it,indicating the involvement of the large formation of ABA in cell senescence under Sb（Ⅲ）treatment.The addition of different forms of Sb did not significantly affect the content of salicylic（SA）despite that there were non-significant increases in its content when subjected to different forms of Sb.Above results might indicate that the SA has a limited role in alleviating the stress of different forms of Sb.更多还原