Proteomic analysis of differentially expressed proteins in longan flowering reversion buds

A proteomic approach was taken to compare the proteomes of normal flowering buds and flowering reversion buds in longan (Dimocarpus longan Lour. cv. Longyou). Two-dimensional gel electrophoresis (2-DE), coupled with mass spectroscopy and protein database searching, recognized 18 proteins that were differentially expressed in flowering reversion buds. Eleven of these were down-regulated, whereas seven were up-regulated. A subset of 13 proteins was identified by MALDI-TOF-TOF/MS and classified into regulatory proteins (kinase, 20S proteasome alpha 6 subunit, putative alpha 7 proteasome subunit, auxin-induced protein, and abscisic stress ripening-like protein), antioxidant-related proteins (Chain A, GDP-mannose-3′,5′-epimerase, putative lactoylglutathione lyase, and Chain A, ascorbate peroxidase), pollen fertility-related proteins (putative leucoanthocyanidin reductase 2, and putative isoflavone reductase), photosynthesis-related proteins (large subunit, ribulose-bisphosphate carboxylase–oxygenase), and molecular chaperones (disulfide isomerase). Among them, regulatory and antioxidant-related proteins accounted for almost two-thirds of these proteins, suggesting that they may play a more important role in bud differentiation. Identification of these proteins provides insights that may lead to a better understanding of the molecular basis for flowering reversion in longan.