MEASUREMENT OF INTRACELLULAR PH OF MAIZE SEEDS (ZEA-MAYS) DURING GERMINATION BY P-31 NUCLEAR-MAGNETIC-RESONANCE SPECTROSCOPY

The P-31 NMR spectra of germinating maize seeds showed a single broad resonance that shifted its position as germination proceeded(studied b etween 0 and 10 days). The resonance was shown to originate from the p hosphate groups of phytine (Mg2+, Ca2+ and K+ salt of myoinositol hexa kisphosphate) in a subcellular compartment of the embryo scutellar cel ls. A series of calibration curves for the chemical shift dependence o f the phytate resonance in the presence of Mg2+ and Ca2+ were construc ted. These calibration curves allowed us to determine that an acidific ation of the phytate containing compartment in the seed embryo takes p lace, reaching a minimum at about pH 4 after three days of germination . This acidification could be important in allowing phytate solubiliza tion for export to growing parts of the maize seedling.