Sr<sup>2+</sup>在印度芥菜幼苗中的富集、亚细胞分布及贮存形态研究

赖金龙; 杨垒滟; 付倩; 何娇; 陶宗娅; 罗学刚

文章摘要

赖金龙,杨垒滟,付倩,何娇,陶宗娅,罗学刚.Sr²⁺在印度芥菜幼苗中的富集、亚细胞分布及贮存形态研究[J].农业环境科学学报,2015,34(11):2055-2062.

Sr²⁺在印度芥菜幼苗中的富集、亚细胞分布及贮存形态研究

Bioaccumulation, Subcellular Distribution and Chemical Forms of Strontium in Brassica juncea L.

投稿时间：2015-05-29

DOI：10.11654/jaes.2015.11.003

中文关键词: 锶富集亚细胞分布化学形态印度芥菜

英文关键词: strontium bioaccumulation subcellular distribution chemical form Brassica juncea L.

基金项目:国家核设施退役及放射性废物治理科研重点项目(14ZG6101);四川省教育厅理工科重点课题(14ZA0030);四川省教育厅大学生创新创业训练计划项目(201410636040)

作者	单位	E-mail
赖金龙	四川师范大学生命科学学院, 成都 610101
杨垒滟	四川师范大学生命科学学院, 成都 610101
付倩	四川师范大学生命科学学院, 成都 610101
何娇	四川师范大学生命科学学院, 成都 610101
陶宗娅	四川师范大学生命科学学院, 成都 610101	t89807596@163.com
罗学刚	西南科技大学生物质材料教育部工程研究中心, 四川绵阳 621010

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中文摘要:

为研究印度芥菜对Sr²⁺的富集、转运特性,解释超富集植物对Sr²⁺的解毒和富集机理,采用水培法培养印度芥菜幼苗至两片真叶,置于含锶[ρ(Sr²⁺)167(CK)~350 mg·L^-1]的营养液中处理7 d后取样,通过差速离心法和化学试剂提取法分离提取植物器官、细胞的亚细胞组分和不同化学形态的Sr²⁺,原子吸收分光光度法测定各器官(根、茎和叶)、各亚细胞组分及不同化学形态的Sr²⁺含量.结果显示:印度芥菜各营养器官对Sr²⁺的富集量为"叶> 茎> 根",地上部分含量占总含量的84.93%~90.46%,转移系数(TF)达到5.63~9.48;生物富集系数(BCF)达到8.21~12.34;各器官中Sr²⁺的亚细胞分布主要集中在细胞壁和可溶性组分中,相对含量达到95.62%~100%;细胞核、前质体、叶绿体和线粒体等细胞器仅含少量的Sr²⁺(<2.92%);Sr²⁺在印度芥菜根中主要以果胶酸盐、蛋白质结合态或吸附态存在,茎、叶中主要以水溶性有机酸盐和一代磷酸盐的形态存在.研究结果表明:质膜转运蛋白介导的跨膜运输是印度芥菜根系吸收Sr²⁺的主要途径,将Sr²⁺以结合态的形式富集到根部,再以水溶态的形式将Sr²⁺经茎部转运至叶中贮存;同时,通过细胞壁的阻滞作用,将Sr²⁺结合固定在细胞壁,并将进入细胞质基质的一部分Sr²⁺转运到液泡内,暂时或"永久性"存贮;通过区域化分布有效降低了细胞器、胞质溶胶(cytosol)及内含物中的Sr²⁺含量,极大地减缓了Sr²⁺对细胞器的功能性损伤,此为印度芥菜对耐受Sr²⁺胁迫的重要机理之一.

英文摘要:

This study examined the characteristics of uptake, accumulation, subcellular distribution, and chemical forms of Sr²⁺ in Brassica juncea seedlings at the two-leaf stage exposed to varying doses of Sr²⁺[ρ(Sr²⁺)167(CK)~350 mg·L^-1] for 7 days. The accumulation of Sr²⁺ in plant organs displayed the following sequence:leaves > stems > roots. Between 84.93%~90.46% of Sr²⁺ in the plant was accumulated in the aboveground parts(leaves and stems). Translocation factor(TF) and bioaccumulation factor(BCF) of Sr²⁺ were 5.63~9.48 and 8.21~12.34, respectively. Subcellular distribution showed that 95.62%~100% of plant Sr²⁺ was localized in the cell walls and soluble fractions, with 2.92% of Sr²⁺ accumulated in organelles(including nucleus, chloroplast/proplastid and mitochondrion). Plant Sr²⁺ existed in different chemical forms. In roots, the greatest amount of Sr²⁺ was found in 1 mol·L^-1 NaCl-extractable fraction, while most of the Sr²⁺ was extracted by dH2O in leaves and stems. For Sr²⁺ uptake by Brassica juncea, Sr²⁺ was first crossed through root plasma membrane mediated by plasma membrane transporters, combined with pectates and proteins in the roots, and then transported in solution to the leaves. In leaves, most of Sr²⁺ was adsorbed on the cell wall, and Sr²⁺ in the cytosol was transported into vacuoles for provisional or permanent storage. As a result, Sr²⁺ content in organelles was effectively reduced, which may greatly alleviate the damage of Sr²⁺ to organelles. Therefore, Sr²⁺ location in the cell walls and vacuoles may contribute jointly to the accumulation and tolerance of Sr²⁺ in Brassica juncea.

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