Abstract
Under environmental stresses, excessive light in chloroplasts result in oxidization of cell components by reactive oxygen species. Aldehydes and ketones derived from lipid peroxides inhibit the Calvin cycle in the chloroplasts. On the other hand, the over-expression of aldehyde scavenging enzymes in plants enhance the tolerance to environmental stresses. Thus, aldehydes and ketones are involved in environmental stresses. To examine what kinds of aldehydes and ketones are produced in chloroplasts, extract from spinach chloroplasts was derivatized with 2,4-dinitrophenylhydrazine and analyzed with HPLC. According to comparison with standard compounds, 8 kinds of saturated aldehydes such as butyraldehyde, n-hexanal and n-nonanal, 3 kinds of α,β-unsaturated aldehydes such as 2E-hexenal and 2E-nonenal and at least 9 kinds of unidentified aldehydes and ketones were detected. The most abundant compounds were 12-oxophytodienoic acid and acetone (35 μmol/mg Chl, 15 μmol/mg Chl, respectivly).
