Plant Gene Engineering Center, Chinese Academy of Sciences Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, Guangdong Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China.
Plant Gene Engineering Center, Chinese Academy of Sciences Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, Guangdong Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China.
N Biotechnol. 2019 Jan 25;48:29-34. doi: 10.1016/j.nbt.2018.04.004. Epub 2018 Apr 21.
Cadmium (Cd) as a carcinogen poses a great threat to food security and public health through plant-derived foods such as rice, the staple for nearly half of the world's population. We have previously reported that overexpression of truncated gene fragments derived from the rice genes OsO3L2 and OsO3L3 could reduce Cd accumulation in transgenic rice. However, we did not test the full length genes due to prior work in Arabidopsis where overexpression of these genes caused seedling lethality. Here, we report on limiting the overexpression of OsO3L2 and OsO3L3 through the use of the stress- inducible promoter RD29B. However, despite generating 625 putative transformants, only 7 lines survived as T1 seedlings and only 1 line of each overexpressed OsO3L2 or OsO3L3-produced T2 progeny. The T2 homozygotes from these 2 lines showed the same effect of reducing accumulation of Cd in root and shoot as well as in T3 grain. As importantly, the concentrations of essential metals copper (Cu), iron (Fe), manganese (Mn) and zinc (Zn) were unaffected. Analysis of the expression profile suggested that low Cd accumulation may be due to high expression of OsO3L2 and OsO3L3 in the root tip region. Cellular localization of OsO3L2 and OsO3L3 indicate that they are histone H2A interacting nuclear proteins in vascular cells and especially in the root tip region. It is possible that interaction with histone H2A modifies chromatin to regulate downstream gene expression.
镉（Cd）作为一种致癌物质，通过稻米等植物源性食物对食品安全和公众健康构成了极大威胁，稻米是全球近一半人口的主食。我们之前曾报道过，过量表达来自水稻基因 OsO3L2 和 OsO3L3 的截断基因片段可减少转基因稻米中 Cd 的积累。然而，由于先前在拟南芥中的工作表明这些基因的过表达会导致幼苗致死，因此我们没有测试全长基因。在这里，我们通过使用应激诱导启动子 RD29B 来限制 OsO3L2 和 OsO3L3 的过表达。然而，尽管生成了 625 个可能的转化体，但只有 7 个 T1 苗幸存下来，并且只有每个过表达 OsO3L2 或 OsO3L3 的 T2 后代中的 1 个系存活。这两个系的 T2 纯合子表现出与 T3 谷物一样减少根和茎叶中 Cd 积累的相同效果。同样重要的是，必需金属铜（Cu）、铁（Fe）、锰（Mn）和锌（Zn）的浓度不受影响。表达谱分析表明，低 Cd 积累可能是由于 OsO3L2 和 OsO3L3 在根尖区域的高表达所致。OsO3L2 和 OsO3L3 的细胞定位表明，它们是血管细胞中与组蛋白 H2A 相互作用的核蛋白，尤其是在根尖区域。与组蛋白 H2A 的相互作用可能会修饰染色质以调节下游基因表达。
