Proteomics And Transcriptomics Analysis Of Dormant Terminal Buds Of Populus Simonii×P. Nigra

Induction and break of bud dormancy are important features for perennial plants surviving extreme seasonal variations in climate. However, the molecular mechanism of the dormancy regulation, still remain poorly understood. To better understand the molecular basis of poplar bud dormancy, in this study, we employed label-free quantitative proteomics and Solexa sequencing transcriptomics for investigation of complex protein expression in Populus simonii×P. nigra dormant buds during dormancy induction, dormancy, and dormancy break in Harbin, China,(E126°37’, N45°42’), with the aim of providing an overview of the biology of bud dormancy and elucidating the mechanisms responsible for differences in metabolic pathways. We used a label-free quantitative proteomics method for investigation of differential protein expression in apical buds of poplar. Among these identified over300proteins during poplar bud dormancy, there are74significantly altered proteins, most of which involved in carbohydrate metabolism (22%), redox regulation (19%), amino acid transport and metabolism (10%), and stress response (8%). Thirty-one of these proteins were up-regulated, five were down-regulated during three phases, and thirty-eight were expressed specifically under different conditions. Pathway analysis suggests that there are still the presence of various physiological activities and a particular influence on photosynthesis and energy metabolism during poplar bud dormancy. Differential expression patterns were identified for key enzymes involved in major metabolic pathways such as glycolysis and the pentose phosphate pathway, thus manifesting the interplay of intricate molecular events in energy generation for new protein synthesis in the dormant buds. Furthermore, there are significant changes present in redox regulation and defense response proteins, for instance in peroxidase and ascorbate peroxidase.In the transcriptomics study,we analyzed the most differentially regulated genes with a log2ratio>2or <-2using a greater statistically significant value (P<0.001) as well as false discovery rates (FDR<0.01), representing154up-and408down-regulated transcripts. The differential genes are involved in transcription regulation, energy metabolism, protein kinase, stress response, hormone signal transduction and other biological function, and are association with stress resistance of plant growth. Among them, some genes related transcription are over express in bud1, especially the ribosome gene expression, suggest that poplar bud dormancy process firstly occurs in transcription level; The cell cycle related genes in bud1and bud3are up expression that imply the bud dormancy into and break. Analysis finds that mRNA and protein involve in the metabolism and energy conversion expression trend is similar. While mRNA and Protein expression abundant of the genes that are related to metabolism and energy conversion is significantly different. The inconsistency of the transcription and protein expression profiles may provide important clues to the research of post-transcriptional regulation of stress resistance genes.