Proteomic analysis of de-etiolated rice seedlings upon exposure to light.

Two-week-old dark-grown rice seedlings were de-etiolated upon exposure to light. A comparison of 2-DE protein profiles between the dark-grown control and the rice seedlings illuminated respectively for 6, 12 and 24 h revealed 52 differentially expressed CBB-stained spots. Of these changed spots, the identity of 51 protein spots was determined by MALDI-TOF MS. Of these identified proteins, 13 proteins were related to light reactions of photosynthesis, photosynthetic carbon assimilation and chlorophyll biosynthesis, indicating the complex process of biogenesis of photosynthetic apparatus was correlated to the transition from a dark-grown (etiolated) to a light-grown (de-etiolated) morphology. In addition, three proteins related to antioxidation and detoxification decreased in de-etiolated rice seedlings implied, that the etiolated rice seedlings possibly be under an oxidative stress which could be released during their early stages of de-etiolation. The increase of S-adenosylmethionine synthetase that is involved in the biosynthesis of the phytohormone ethylene might contribute to the phenotypic development of the apical hook in the de-etiolated rice seedlings. These results yield a comprehensive picture of the post-transcriptional response for de-etiolation of rice seedlings and serve as a basic platform for further characterization of gene function and regulation in light-induced development of plants.