Plant Science Department, Rothamsted Research, Harpenden AL5 2JQ, UK.
Plant Physiol. 2011 Dec;157(4):2227-39. doi: 10.1104/pp.111.183897. Epub 2011 Oct 4.
Sulfate and selenate uptake were investigated in both selenium (Se) hyperaccumulators (Astragalus racemosus and Astragalus bisulcatus) and closely related nonaccumulator species (Astragalus glycyphyllos and Astragalus drummondii). Sulfur (S) starvation increased Se accumulation, whereas increased selenate supply increased sulfate accumulation in both root and shoot tissues. cDNAs for homologs of groups 1 to 4 sulfate transporters were cloned from these Astragalus species to investigate patterns of expression and interactions with sulfate and selenate uptake. In contrast to all other previously analyzed plant species, abundant gene expression of putative sulfate transporters was observed for both Se-hyperaccumulating and nonaccumulating Astragalus, regardless of S and Se status. Furthermore, quantitative analysis of expression indicated a transcript level in Se-hyperaccumulating Astragalus comparable with other plant species under S deprivation. The high expression of sulfate transporters in certain Astragalus species may lead to enhanced Se uptake and translocation ability and therefore may contribute to the Se hyperaccumulation trait; however, it is not sufficient to explain S/Se discriminatory mechanisms.
研究了硫酸盐和硒酸盐在硒（Se）超积累植物（紫云英和二色补血草）和与其密切相关的非积累种（甘草和德拉蒙德氏黄芪）中的吸收。硫（S）饥饿增加了 Se 的积累，而增加的硒酸盐供应增加了根和茎叶组织中硫酸盐的积累。从这些黄芪物种中克隆了硫酸盐转运蛋白 1 组至 4 组的同源物 cDNA，以研究其与硫酸盐和硒酸盐吸收的表达模式和相互作用。与所有其他先前分析的植物物种不同，无论 S 和 Se 状态如何，都观察到 Se 超积累和非积累黄芪中大量的硫酸盐转运蛋白的基因表达。此外，表达的定量分析表明，在 S 剥夺条件下，Se 超积累黄芪的转录水平与其他植物物种相当。某些黄芪物种中硫酸盐转运蛋白的高表达可能导致增强的 Se 吸收和转运能力，从而有助于 Se 超积累特性；然而，这不足以解释 S/Se 区分机制。
