An alternative strategy to tackle the problem consists in the isolation of cereal mutants accumulating less phytic P and more free phosphate in the seed (Raboy et al. 1990, Rasmussen et al. 1998). We have chosen to apply this approach in maize.
Since normal mature maize seeds contain high phytate phosphate and low free phosphate levels, a screening for high level of free phosphate in seeds provides a quick and inherently sensitive assay for the detection of lpa (low phytic acid) mutants. A population of EMS (ethyl methanesulfonate)-induced mutants was thus generated using the pollen-treatment method and approximately 600 M2 families were screened. The first assay was carried out by titrating free phosphate using the molybdate staining method. Putative mutants were then challenged by a TLC (Thin Layer Chromatography) method allowing the simultaneous detection of free phosphate and phytate.
One monogenic recessive mutation (named lpa 241), causing approximately
a ten fold increase in the amount of free phosphate titratable and a reduction
of about 90 % of phytic acid, apparently did not affect normal germination
or seedling growth. Genetic analysis of this mutation, as well as its biochemical
characterization aimed at identifying the biosynthetic step involved are
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