| Summary: | In vivo 31P NMR spectra of wheat, soybean and mustard seeds were recorded during ripening. Signals were detected from phosphomonoesters, cytoplasmic and vacuolar inorganic phosphate (P1), phytate, nucleoside triphosphate (NTP) and nucleoside diphosphosugars. The spectra of extracts showed an accumulation of phytate during development, accompanied by a decrease in inorganic phosphate, and this was reflected in the in vivo spectra. The intrinsic width of the resonances was a significant obstacle to the interpretation of the in vivo spectra in all three cases, and the problem became more severe with increasing maturity. However, it was still possible to use the chemical shift of the cytoplasmic P1 signal to monitor cytoplasmic pH in both soybean and mustard, and the results provide evidence for the existence of a hypoxic state in developing seeds during the active biosynthetic phase. © 1997 John Wiley and Sons, Ltd.
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