Study On Differentially Expressed Proteins During Development Of Longan Cotyledon Embryos

Longan (Dimocarpus longan Lour.) belongs to Sapindaceae family is a famous subtropical fruit, and also has important economic value. The large seed in longan fruit is one of important factors influencing the quality. Studies on embryo development have made significant progress in plant physiological research, but we can't elucidate the mechanism of embryo development completely until now.Here, two-dimensional electrophoresis (2-DE) was conducted to isolate the protein in the'Qingkebaoyuan'longan cotyledon embryos. By comparing the biological function of differentially expressed proteins during different development stages, the molecule essence of cotyledon embryos development was revealed. By optimizing the preparation of protein sample, the parameters of 2-DE and staining, we established the suitable proteomic research platform of longan embryos.More than 1000 spots were reproducibly detected in Coomassie brilliant blue stained gels with a pI range of 4–7 in the first dimension and using homogeneous 12.5% polyacrylamide gels in the second dimension. After PDQuest software analysis, we found 46 proteins were remarkably altered during the cotyledon embryo development. 36 spots with with the expression changed more than two times were identified by matrix-assisted laser desorption ionization-time of flight-tandem mass spectrometry (MALDI-TOF-TOF/MS). After searching database 26 proteins were successfully identified with a protein identification rate of 72.2%. Among them, 13 protein spots were up-regulated , 11 protein spots were down-regulated and 2 protein spots were undulatory-regulated during cotyledon embryo development. These proteins were subdivided in functional categories:metabolism and energy (23%), secondary metabolism (15%), protein metabolism (27%), antioxidation (4%), nucleic acid metabolism (4%) and uncalssification protein(27%), some of which were first discovered been associated with embryo development. Western blot analysis were further carried out to validate the differential expression of ascorbate peroxidase.We obtained the important information of development of longan cotyledon embryos at protein level through analyzing the function of the differentially expressed proteins during development of longan cotyledon embryos. This provides a basis for further study on molecular mechanism of longan embryonic development.