Analysis Of Differential Proteins In Longan (Dimocarpus Longan Lour.) Flowering Reversion Buds

Logan is the special local product fruit in south of China,occupies the important site in domestic markets and foreign trade markets.Big and small year outcome of fruits is the major cause in affecting yield in Logan production.As the production of "small" year is always less than half of "big" year,so longan floral reversion has become a great problem in the production of longan.So the settlement of big and small year production of longan has great value in the production.In this study, proteomic techniques and methods were used to compare the proteomes between longan normal flower buds and floral reversion buds,and analyzed the different proteins closely with longan floral reversion.The results of this study were as follows:Protein extraction method is an important technological factor which directly influence the protein spot number and map quality in 2-DEgel.In this study,we compared two different methods,trichloroacetic acid/acetone precipitation(TCA)and phenol extraction(Phe),to determine their efficiency in extracting total proteins from longan buds by 2-DE analysis.The results showed that TCA does not work in extraction protein from longan flower buds.But the 2-DE gels of Phe method had a clean background,and protein spots were clearly seen.So Phe method is suited for longan bud protein extraction.Proteomic approach was applied to compare the proteome changes between normal flowering and flowering reversion buds in longan.There were 18 proteins differentially expressed,11 proteins down-regulated and 7 proteins up-regulated.A total of 13 proteins were identified by MALDI-TOF-TOF/MS.The identification rate was 72%.Among these proteins,one protein was named by a part of its gene sequence, whose function has not yet been studied.These 12 proteins were categorized into classes by function related to pollen fertility(putative leucoanthocyanidin reductase 2,Putative isoflavone reductase and Abscisic stress ripening-like protein), antioxidant related protein(ChainB,Gdp-Marmose-3',5' -Epimerase,Putative lactoylglutathione lyase and Chain A,scobate Peroxidase),photosynthesis (Ribulose-bisphosphate carboxylase large subunit),regulation proteins(Kinase,20S proteasome alpha 6 subunit,Putative alpha7 proteasome subunit and Auxin-induced protein)and chaperone(Disulfide isomerase).As a result of the changes in expression level of these proteins,longan flower buds develop abnormally,which might lead to flowering reversion.