邻苯二甲酸酯(PAEs)高/低累积水稻品种吸收和代谢PAEs差异及其机理

Phthalic acid esters (PAEs) is one class of ubiquitous environmental organic pollutants and endocrine disrupting chemicals. Our previous studies indicated that uptake and accumulation of PAEs by different cultivars of rice (Oryza sativa L.) and Chinese flowering cabbage were species-specific and cultivar-specific. The variation may result from uptake and transportation as well as metabolism by plants. However, until now, very few study has reported about these topics. In this project, high/low PAE-accumulating genotypic rice cultivars screened previously by our group will be selected as materials, and cultivated in hydroponic solution and soil spiked with PAEs. The samples of plants, soil and solution will be collected, and PAEs in these samples will be extracted and measured by gas chromatography coupled with mass spectrometry (GC/MS). The aims of this study are to (1) investigate the main uptake pathway of PAEs by the two cultivars of rice, especially by their roots, and subcellular distribution of PAEs in rice roots, stems and leaves as well as their effect factors; (2) clarify the metabolism kinetics of PAEs by rice in vivo and in vitro, the main metabolism tissues, metabolism effectiveness, their key enzymes, and the control factors of the physiology and biochemistry, and infer its possible pathway of metabolism. All results above would be helpful to elucidate the variation and its mechanism of the high/low PAE-accumulating cultivars, and will provide scientific basis for selecting pollution-free (or low PAE accumulation) rice cultivars and for the safety of agricultural products.

邻苯二甲酸酯(PAEs)是一类普遍存在的环境有机污染物和内分泌干扰物。我们前期研究表明，水稻、菜心等作物对PAEs 的吸收累积存在品种差异(基因型差异)。该差异可能由植物吸收运移及其自身代谢作用所导致，但目前国内相关研究鲜见报道。本项目将以前期筛选获得的PAEs高、低累积基因型水稻品种为材料，采用营养液培养试验、土壤盆栽试验和GC/MS分析技术等相结合，研究水稻特别是其根部对PAEs吸收累积的主要途径、PAEs 在水稻体内亚细胞水平的分布及其影响因素，查明水稻对PAEs的代谢动力学、主要代谢部位、代谢效率及代谢关键酶，推测其代谢途径，从而阐明PAEs高、低累积品种水稻累积PAEs差异的机理，为保障农产品安全提供科学依据。

邻苯二甲酸酯(PAE)是一类全球关注的毒性有机污染物。前期发现水稻对PAE的吸收累积存在品种差异，但该差异是否由植物吸收及其自身代谢所导致尚未清楚。本项目以前期获得的PAE高、低累积水稻品种（分别为培杂泰丰和丰优丝苗）为材料，研究了水稻对PAE吸收途径、吸收和代谢动力学、水稻根系分泌物等对不同品种水稻累积PAE差异的影响机制。项目揭示了水稻吸收PAE主要途径及生理生化影响机制，即主要通过根系主动吸收、茎叶吸收/吸附PAE；蒸腾作用和韧皮部迁移会影响水稻吸收PAE；PAE主要分布于水稻细胞壁和细胞器。明确了水稻根系对PAE的吸收动力学特征，其吸收量随时间延长而增加，分为快速和慢速吸收2个阶段。培杂泰丰根系对PAE吸收能力及其速率常数均大于丰优丝苗，前者对PAE亲和力比丰优丝苗大，使前者吸收更多PAE。水稻根系分泌物及低分子有机酸降低土壤对PAE的吸附作用，促进土壤PAE解吸和活化，且培杂泰丰根系分泌物促解吸比丰优丝苗强；水稻土不同粒径组分对邻苯二甲酸正二丁酯（DBP）吸附能力随粒径减小呈增大趋势；水稻秸秆制备的生物质炭显著促进土壤各粒径组分对DBP的吸附而降低解吸率。阐明了水稻代谢PAE的途径和关键酶等。两个品种水稻体内及体外(粗酶液)均能代谢DBP，形成邻苯二甲酸单丁酯和邻苯二甲酸，根系及其粗酶液代谢能力显著高于茎叶。体外代谢和酶抑制剂试验证实了羧酸酯酶是DBP代谢的关键酶。培杂泰丰比丰优丝苗对DBP的代谢能力强。培杂泰丰根系内生菌多样性及具有降解PAE功能菌属的相对丰度高于丰优丝苗，可能影响它们对DBP的代谢差异。本项目从水稻吸收途径、吸收和代谢动力学和酶代谢机制、生理生化影响机制等阐明了PAE高、低累积水稻品种差异的机理，为保障农产品安全提供了科学依据。. 依托本项目，发表了SCI收录论文10篇，中文核心期刊论文2篇；获授权专利3件；培养了7名硕士生、4名博士后。