The maize lpa241 mutation causes a remarkable variability of expression and some pleiotropic effects

Phytic acid is a nearly ubiquitous component of plant seeds, supplying both phosphate (P) and cations during germination. However, during digestion, the phytic acid form of P is not bioavailable for monogastric animals. A possible solution to this problem is the isolation of cereal mutants accumulating less phytic P and more free P and cations in the seed (low phytic acid, lpa). In a previously published study, we described a single, recessive lpa mutation (named lpa241) in maize (Zea mays L.) mapping on chromosome IS in the same location of the lpa1-1 mutant, showing a decrease in the expression of the first enzyme of phytic acid pathway, myo-inositol-3-phosphate synthase (MIPS). The goal of this study was to gain further information about the nature of lpa241 mutation as well as its effects on seed physiology and plant growth. We present new results of genetic, molecular, and histological analyses demonstrating that lpa241 is indeed allelic to lpa1-1, its MIPS1S coding region does not show a relevant molecular lesion, is accompanied by a strong reduction in globoid number and size, and shows highly variable expression causing some negative pleiotropic effects related to embryo development and size, germination rate, seedling growth rate, and ear size. The origin and the consequences of the lpa241 mutation led us to advance the hypothesis of an epigenetic nature of the mutation and to emphasize the role of myo-inositol and its derivatives during seed maturation, germination, and seedling growth.