Chemiluminescence of Soybean Seeds: Spectral Analysis, Temperature Dependence and Effect of Inhibitors

Abstract

Abstract— The spontaneous light emission of soybean seeds is enhanced 4–8 times during the first minute after water imbibition. Other solvents are also effective. The temperature dependence of soybean chemiluminescence identifies two reactions with activation energies of 20 and 68 kJ/mol corresponding to the lipoxygenase reaction and to the autoxidation of unsaturated fatty acids, respectively. Free radical scavengers and lipoxygenase inhibitors decrease soybean photoemission. The singlet oxygen probe 1,4‐diazabicyclo‐[2,2,2]‐octane (DABCO) increases soybean photoemission. The emission spectra of soybean seeds under a variety of conditions show bands between 450 and 720 nm with 50–70% of the emission over 600 nm. The experimental evidence is consistent with singlet oxygen being one of the emitting species, however, due to the complexity of the system it is likely that other chemiluminescent species are also formed.

Spontaneous Chemiluminescence of Soybean Embryonic Axes during Imbibition

“…Both processes have been identified on the basis of their Arrhenius activation energies (8). The peroxy-radicals from unsaturated fatty acids are intermediates of the autooxidation process whereas the lipoxygenase reaction yields peroxy-radicals in a side reaction (8,11,15). The predominantly red emission is consistent with 1o22 being one of the species responsible for photoemission (8,10).…”

“…Soybean seeds show spontaneous low level chemiluminescence, which sharply increases upon imbibition (6,8). Two processes, the nonenzymic autooxidation of unsaturated fatty ' Supported by grants acids and the lipoxygenase-catalyzed reaction (8), lead, through common intermediates (ROO') to light emission. Both processes have been identified on the basis of their Arrhenius activation energies (8).…”

“…Low level chemiluminescence is currently regarded as a measurement of the steady state level of oxy-radicals and singlet oxygen formed during the lipoperoxidation process and seems to afford a useful noninvasive and nondestructive assay for these reactive species in intact tissues (5,7,10). Soybean seeds show spontaneous low level chemiluminescence, which sharply increases upon imbibition (6,8). Two processes, the nonenzymic autooxidation of unsaturated fatty ' Supported by grants acids and the lipoxygenase-catalyzed reaction (8), lead, through common intermediates (ROO') to light emission.…”

“…The peroxy-radicals from unsaturated fatty acids are intermediates of the autooxidation process whereas the lipoxygenase reaction yields peroxy-radicals in a side reaction (8,11,15). The predominantly red emission is consistent with 1o22 being one of the species responsible for photoemission (8,10). Considering the chemical reactivity of oxy-radicals and of 102 (5,7,13) that could lead to membrane and nucleic acid damage, it is possible that an increased level of these reactive species during the early imbibition phase may have a deleterious role on embryo and seed performance during germination.…”

“…Two processes, the nonenzymic autooxidation of unsaturated fatty ' Supported by grants acids and the lipoxygenase-catalyzed reaction (8), lead, through common intermediates (ROO') to light emission. Both processes have been identified on the basis of their Arrhenius activation energies (8). The peroxy-radicals from unsaturated fatty acids are intermediates of the autooxidation process whereas the lipoxygenase reaction yields peroxy-radicals in a side reaction (8,11,15).…”