Direct Observation of the Effects of 3,5-Diisopropylsalicylate and Light on Maize Coleoptiles using 31P NMR

Metabolic effects caused by 3,5-diisopropylsalicylate (DIPS) and light were observed in etiolated maize coleoptiles using in vivo³¹P NMR spectroscopy. A decrease in the nucleotide triphosphate (NTP) resonances and an increase in nucleotide diphosphate hexose (NDP-hexose) signals were induced by 200 μM DIPS, with an acidification of the cytoplasm occurring in a fraction of the cells. Increased hexose phosphate and NDP-hexose signals, accompanied by a decreased cytoplasmic Pi resonance, were observed under intermittent blue light, while in red light only the increase of the hexose-P and decrease in cytoplasmic Pi signals occurred. These results provide evidence for an analogy between the action of DIPS and light at the molecular level, while the similar effects of red and blue light are compatible with phytochrome as the principal photoreceptor responsible for the metabolic changes.