Proteomic analysis of de‐etiolated rice seedlings upon exposure to light

Abstract

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.

Label-free Quantitative Proteomics Analysis of Etiolated Maize Seedling Leaves during Greening

“…As expected, in our study 25 membrane proteins were identified and quantified (Table I); to our knowledge, few gel-based proteomics studies have identified so many membrane proteins. For example, we identified POR, which is abundant in etiolated seedlings but has never been identified in similar experiments using 2-DE methods (3,4). These results indicate that our newly developed MS E -based label-free method is robust, highly reproducible, and sensitive and thus is ideally suited to proteomics studies of this type.…”

“…Although many proteomics investigations have been done on lightregulated proteins in C 3 plants during seedling de-etiolation, particularly in rice and Arabidopsis (3,4), few such studies have been done in C 4 plants. Maize, which is quite distinct from Arabidopsis and rice, is a prototypical C 4 plant that exhibits classical Kranz leaf anatomy during development (34,35).…”

“…Upon exposure to light, seedlings undergo a number of dramatic changes, including a substantial reduction in the rate of elongation, opening of the apical hook, expansion of true leaves, and development of mature chloroplasts (5,6). The transition from etiolated to de-etiolated seedlings is a very complicated process that includes chloroplast development, pigment synthesis, and assembly of the photosystems in thylakoids, all of which are accomplished by and depend on the differential expression of a large number of genes (4). Phytochromes play an important role in regulating de-etiolation (7)(8)(9), and certain photosynthesisrelated genes also can be regulated by light; for example, the genes encoding chlorophyll a/b-binding light-harvesting proteins are down-regulated by excess light exposure (10), and the gene encoding Rieske FeS protein (10) and genes GAPA and GAPB, which encode different subunits of chloroplast glyceraldehyde-3-phosphate dehydrogenase (11) in Arabidopsis, are up-regulated by light.…”

“…Light-induced greening of angiosperms often has been used as the model to study mechanisms of light regulation (3,4). Both dicotyledonous and monocotyledonous dark-grown seedlings present typical etiolated characters of elongated hypocotyls and stems as well as undifferentiated chloroplast precursors (3)(4)(5). Upon exposure to light, seedlings undergo a number of dramatic changes, including a substantial reduction in the rate of elongation, opening of the apical hook, expansion of true leaves, and development of mature chloroplasts (5,6).…”

“…Light-induced greening of angiosperms often has been used as the model to study mechanisms of light regulation (3,4). Both dicotyledonous and monocotyledonous dark-grown seedlings present typical etiolated characters of elongated hypocotyls and stems as well as undifferentiated chloroplast precursors (3)(4)(5).…”