Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, UK.
PLoS Genet. 2012 Sep;8(9):e1002923. doi: 10.1371/journal.pgen.1002923. Epub 2012 Sep 6.
Understanding the mechanism of cadmium (Cd) accumulation in plants is important to help reduce its potential toxicity to both plants and humans through dietary and environmental exposure. Here, we report on a study to uncover the genetic basis underlying natural variation in Cd accumulation in a world-wide collection of 349 wild collected Arabidopsis thaliana accessions. We identified a 4-fold variation (0.5-2 µg Cd g(-1) dry weight) in leaf Cd accumulation when these accessions were grown in a controlled common garden. By combining genome-wide association mapping, linkage mapping in an experimental F2 population, and transgenic complementation, we reveal that HMA3 is the sole major locus responsible for the variation in leaf Cd accumulation we observe in this diverse population of A. thaliana accessions. Analysis of the predicted amino acid sequence of HMA3 from 149 A. thaliana accessions reveals the existence of 10 major natural protein haplotypes. Association of these haplotypes with leaf Cd accumulation and genetics complementation experiments indicate that 5 of these haplotypes are active and 5 are inactive, and that elevated leaf Cd accumulation is associated with the reduced function of HMA3 caused by a nonsense mutation and polymorphisms that change two specific amino acids.
了解镉（Cd）在植物中积累的机制对于通过饮食和环境暴露帮助降低其对植物和人类的潜在毒性非常重要。在这里，我们报告了一项研究，旨在揭示全球范围内 349 个野生拟南芥品系中 Cd 积累自然变异的遗传基础。当这些品系在控制的普通花园中生长时，我们发现叶片 Cd 积累存在 4 倍的差异（0.5-2μg Cd g(-1)干重）。通过结合全基因组关联作图、实验 F2 群体中的连锁作图和转基因互补，我们揭示 HMA3 是唯一负责我们在这个多样化的拟南芥品系群体中观察到的叶片 Cd 积累变异的主要基因座。对来自 149 个拟南芥品系的 HMA3 预测氨基酸序列的分析揭示了 10 种主要的天然蛋白单倍型的存在。这些单倍型与叶片 Cd 积累的关联以及遗传互补实验表明，其中 5 种是有活性的，5 种是无活性的，并且叶片 Cd 积累的增加与 HMA3 功能降低有关，这是由无意义突变和改变两个特定氨基酸的多态性引起的。
