US Department of Agriculture, Agricultural Research Service, Department of Plant Sciences, University of California, Davis, CA 95616, USA.
Planta. 2010 Oct;232(5):1241-50. doi: 10.1007/s00425-010-1243-5. Epub 2010 Aug 24.
Phytic acid (inositol-1,2,3,4,5,6-hexakisphosphate or InsP(6)) is the primary storage form of phosphorus in plant seeds. The rice OsLpa1 encodes a novel protein required for wild-type levels of seed InsP(6) and was identified from a low phytic acid (lpa) mutant exhibiting a 45-50% reduction in seed InsP(6). OsLpa1 is highly conserved in plants and Arabidopsis contains two OsLpa1-like genes, At3g45090 and At5g60760. Analysis of homozygous T-DNA insertion mutants of At5g60760 revealed significantly reduced levels of seed InsP(6) while no changes were observed in seeds of At3g45090 mutants. A double knockout mutant of At5g60760 and At3g45090 was created and its seed InsP(6) content was similar to that of the At5g60760 mutant indicating that At3g45090 does not provide functional redundancy. OsLpa1 was confirmed to be the ortholog of At5g60760 by complementation of a knockout mutant with a cDNA clone corresponding to the largest of three alternative transcripts of OsLpa1. The spatial and temporal expression of At5g60760 during seed development is consistent with its involvement in seed InsP(6) biosynthesis.
植酸（肌醇-1,2,3,4,5,6-六磷酸或 InsP(6)）是植物种子中磷的主要储存形式。水稻 OsLpa1 编码一种新型蛋白，是野生型种子 InsP(6)水平所必需的，是从表现出种子 InsP(6)降低 45-50%的低植酸（lpa）突变体中鉴定出来的。OsLpa1 在植物中高度保守，拟南芥含有两个 OsLpa1 样基因，At3g45090 和 At5g60760。对 At5g60760 纯合 T-DNA 插入突变体的分析表明，种子 InsP(6)水平显著降低，而 At3g45090 突变体的种子没有观察到变化。创建了 At5g60760 和 At3g45090 的双敲除突变体，其种子 InsP(6)含量与 At5g60760 突变体相似，表明 At3g45090 不能提供功能冗余。通过与 OsLpa1 的三个替代转录本中最大的 cDNA 克隆互补，证实 OsLpa1 是 At5g60760 的同源物。At5g60760 在种子发育过程中的时空表达与其参与种子 InsP(6)生物合成一致。
