水稻幼苗对As(Ⅲ)胁迫差异响应的离子组学研究

Ionomic studies of rice seedling differential responses to arsenite stresses

重金属胁迫影响植物体内离子平衡,探究植物体离子网络应对胁迫环境的响应有助于挖掘有毒元素吸收和代谢的潜在机制。本研究以湖南省临武县9种主栽水稻品种为研究对象进行As(Ⅲ)胁迫处理,采用ICP-MS分析技术研究水稻幼苗茎叶和根部组织中离子组(P、K、Mg、Ca、Mn、Fe、Cu、Zn、As、Cr、Co、Cd、Ba、Pb和Sr)响应不同As(Ⅲ)浓度胁迫的变化特征,进一步借助多元统计分析探明各组织离子组变化与As积累之间的关联。结果表明:水稻根部和茎叶组织As含量均随处理浓度增加而增加,且根部相比茎叶更容易积累As;Fe、Ba、Pb和Sr同样表现出根部含量高于茎叶的规律,营养元素(P、K、Mg、Ca和Mn)分布则呈现茎叶组织高于根部的特征,胁迫环境对水稻幼苗两个组织部位各元素分布的影响不同,说明As胁迫干扰水稻组织中离子的分配。聚类热图和主成分分析表明离子组在茎叶和根部出现分离,Mg、K、P、Mn、Ca、Cr、Co、Zn元素倾向于在茎叶富集,而Fe、Sr、Pb、Ba、Cu、As和Cd元素则倾向于在根系中富集。As胁迫处理后,水稻同一组织的元素之间存在多组显著相关性,As与Fe、Cu、Cd、Ba、Pb、Sr在P<0.05显著性水平下呈现正相关关系,As与P、K、Mg、Ca、Mn在P<0.05显著性水平下呈现负相关关系,说明水稻离子组对植株内As的迁移和积累具有调节作用。

Ionomic profiles of plants display correlations with the stress inducing heavy metals to which they are exposed.Investigation of ionomic variation can provide insights into the mechanisms that promote element uptake or detoxification in plants.In this research,nine main rice varieties obtained from Linwu County,Hunan Province were treated with arsenate during hydroponic growth.The elements P,K,Mg,Ca,Mn,Fe,Cu,Zn,As,Cr,Co,Cd,Ba,Pb,and Sr in shoots and roots of rice seedlings subjected to As(Ⅲ)stress were quantitatively analyzed by ICP-MS.Associations between the ionome and arsenic in each tissue were further clarified using multivariate statistical analysis.Arsenic increased in both roots and shoots with increasing concentration of As(Ⅲ)exposure,and roots were more likely to accumulate arsenic than shoots.Fe,Ba,Pb,and Sr showed the same distribution trend as As,whereas the nutrient elements(P,K,Mg,Ca,and Mn)accumulated to higher levels in shoots than roots.The effects on distribution of each element in the two tissues of rice seedlings varied with stress condition,indicating that external As stress interfered with ion distribution in rice tissues.Cluster heat map and principal component analyses showed that ion groups appeared separately in shoots and roots,with Mg,K,P,Mn,Ca,Cr,Co,and Zn tending to be enriched in shoots,while Fe,Sr,Pb,Ba,Cu,As,and Cd tended to be enriched in roots.Multi-set significant correlations among elements could be found in rice tissues.As correlated positively with Fe,Cu,Cd,Ba,Pb,and Sr in roots and shoots(P<0.05),while a significant(P<0.05)negative correlation could be found between As and P,K,Mg,Ca,and Mn,suggesting that ion groupings in rice exert regulatory effects on As migration and accumulation.These study results are expected to provide theoretical references for reducing arsenic contamination in rice.