关键词: 龙眼, 体细胞胚发生, 蛋白质组学, 双向电泳, 质谱

Abstract: 【Objective】The differential expressions of proteome patterns at 5 early developmental stages were analyzed during longan somatic embryogenesis. The results would contribute to the further research for isolation of plant embryo development associated protein genes and studies of plant somatic embryogenesis mechanisms. 【Method】Five embryogenic cultures at early developmental stages from the established longan somatic embryogenesis and regeneration system were obtained after synchronized culture. And their changes of proteomic patterns were investigated by the immobilized pH gradients two-dimensional electrophoresis technology and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF/TOF). 【Result】From 1 203 to 1 798 protein spots could reproducibly be resolved in two-dimensional gels, most of them displayed obvious differences in the expression abundances at different stages and small part of them were of specific expression. On the basis of variations of protein numbers, expression abundances, molecular weight and isoelectric point, the key stages of early somatic embryogenesis in longan were determined, namely from ECII (Embryogenic callus II) to CpECGE (Compact pro-embryogenic cultures globular embryos). Forty-five differentially expressed proteins were identified and the identification rate was 37%. These findings suggested that energy and carbohydrate metabolism and oxidative stress response have a large majority, 22% and 27% respectively. It could be deduced by analyzing the functions of these proteins that the material foundation of longan somatic embryogenesis at early stages was of energy and carbohydrate metabolism, and the precondition of somatic embryogenesis was of oxidative stress response. To ensure the normal development of somatic embryos, these proteins together with the proteins related to cytoskeleton stability, nitrogen metabolism, signal transduction, gene regulation, protein synthesis or modification, and positioning function formed an enormous protein network system of early somatic embryogenesis in longan. 【Conclusion】There had more overall understanding to expression changes of  proteome patterns during the early longan somatic embryogenesis. The number of expressed proteins had a trend of increase after the first decrease, and then reduced again. During the early longan somatic embryogenesis, energy and carbohydrate metabolism is very vigorously, and the proteins related to oxidative stress response may play an important role in modulating the early somatic embryogenesis and development.

Key words: longan (Dimocarpus longan Lour.), somatic embryogenesis, proteomics, two-dimensional electrophoresis, mass spectrometry