Origin and seed phenotype of maize low phytic acid 1-1 and low phytic acid 2-1.
Phytic acid (myo-inositol-1, 2, 3, 4, 5, 6-hexakisphosphate or Ins P(6)) typically represents approximately 75% to 80% of maize (Zea mays) seed total P. Here we describe the origin, inheritance, and seed phenotype of two non-lethal maize low phytic acid mutants, lpa1-1 and lpa2-1. The loci map to two sites on chromosome 1S. Seed phytic acid P is reduced in these mutants by 50% to 66% but seed total P is unaltered. The decrease in phytic acid P in mature lpa1-1 seeds is accompanied by a corresponding increase in inorganic phosphate (P(i)). In mature lpa2-1 seed it is accompanied by increases in P(i) and at least three other myo-inositol (Ins) phosphates (and/or their respective enantiomers): D-Ins(1,2,4,5,6) P(5); D-Ins (1,4,5,6) P(4); and D-Ins(1,2,6) P(3). In both cases the sum of seed P(i) and Ins phosphates (including phytic acid) is constant and similar to that observed in normal seeds. In both mutants P chemistry appears to be perturbed throughout seed development. Homozygosity for either mutant results in a seed dry weight loss, ranging from 4% to 23%. These results indicate that phytic acid metabolism during seed development is not solely responsible for P homeostasis and indicate that the phytic acid concentration typical of a normal maize seed is not essential to seed function.
Raboy
V
V
United States Department of Agriculture-Agricultural Research Service, National Small Grain Germplasm Research Facility, P.O. Box 307, Aberdeen, Idaho 83210, USA. vraboy@uidaho.edu
Gerbasi
P F
PF
Young
K A
KA
Stoneberg
S D
SD
Pickett
S G
SG
Bauman
A T
AT
Murthy
P P
PP
Sheridan
W F
WF
Ertl
D S
DS
D004586:Electrophoresis / Q000379:methods; D007295:Inositol Phosphates / Q000737:chemistry / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D009154:Mutation; D010641:Phenotype; D010710:Phosphates / Q000302:isolation & purification / Q000378:metabolism; D020161:Physical Chromosome Mapping; D010833:Phytic Acid / Q000096:biosynthesis / Q000378:metabolism*; D012639:Seeds / Q000254:growth & development / Q000502:physiology*; D013237:Stereoisomerism; D003313:Zea mays / Q000235:genetics / Q000254:growth & development / Q000502:physiology*
D007295:Inositol Phosphates; D010710:Phosphates; D010833:Phytic Acid