, Volume 232, Issue 5, pp 1241-1250
Date: 24 Aug 2010

Genetic analysis of two OsLpa1-like genes in Arabidopsis reveals that only one is required for wild-type seed phytic acid levels

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Abstract

Phytic acid (inositol-1,2,3,4,5,6-hexakisphosphate or InsP6) is the primary storage form of phosphorus in plant seeds. The rice OsLpa1 encodes a novel protein required for wild-type levels of seed InsP6 and was identified from a low phytic acid (lpa) mutant exhibiting a 45–50% reduction in seed InsP6. 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 InsP6 while no changes were observed in seeds of At3g45090 mutants. A double knockout mutant of At5g60760 and At3g45090 was created and its seed InsP6 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 InsP6 biosynthesis.