Analyses Of Proteome And Respiratory Pathways Of Nectarine Flower Bud During Dormancy Induction

To survive cold and desiccating stress in winter, deciduous fruit trees adopted a strategyprogressive establishing a dormant state within bud in autumn to adapt themselves to thestress, which was acquired during the long course of evolution. Hence, timely establishing thedormant state was an integrated event in bud developmental progress and was essentiallyachieved at the end of dormancy induction. During that stage, sets of unique genes weretemporally expressed in buds to enable themselves to sense the environmental changes and tomodulate their development, leading to a series of complicated but order proteomic changesdistinguished from those of growth period. In this study, combination of2-DE with MSanalysis was used to explore the differentially expressed proteins in floral buds of ten year old‘Shuguang’ nectarine （Prunus persica var.Nectariana cv.Shuguang） tree. Dormancyinduction was artificially divided into three different stages denoted respectively asⅠ、ⅡandⅢ stage. Proteins whose expression levels were at least changed by2-fold during the threestages were selected to further be submitted to MS analysis and physiological changes infloral buds were monitored in parallel. The following results were obtained:1. During the course of dormancy induction,13differentially expressed protein spotswere repeatedly observed and further subjected to MS analysis,11of which were successfullyidentified.7of identified proteins were up-regulated while4of those were down-regulated.To further understand the roles of those13proteins in dormancy induction course, wefunctionally cataloged them.6of up-regulated proteins were classified as stress and defensegroup while one of those felled into photosynthesis group;2of down-regulated proteins wereinvolved in glucolysis and energy metabolism, one of those positively played in cell cycleregulation and cellular elongation, and one of those had an important role in remodeling cellwall and related metabolism.2. During the course of dormancy induction, free water content gradually lowered,especially at Ⅲ stage, which significantly declined; H₂O₂level increased during the first twostages but declined at Ⅲ stage, peaking at Ⅱ stage. 3. During the course of dormancy induction, total respiratory rate declined; activity ofTCA pathway declined, the contribution of PPP pathway to total respiratory rate declined atⅡ stage but increased at Ⅲ stage.4. During the course of dormancy induction, activity of cytochrome electron transportpathway (ρ′V_cyt) and its contribution to total respiratory rate (ρ′V_cyt/V_t) declined, but werehigher than those of alternative respiratory pathway (ρV_alt); activity of alternative respiratorypathway (ρV_alt) and its contribution to tatal respiratory rate (ρV_alt/V_t) declined atⅡstage butincreased at Ⅲ stage.In conclusion, a series of complicated but order changes occurred in bud during thecourse of dormancy induction. The proteomic results suggested that: at the Ⅱ stage, cellularproliferation and growth began to stop; at Ⅲ stage, bud actively acquired and strengthenedits ability to adapt the adverse environment. Experimental results from respiratory metabolismpathway suggested that: TCA pathway and cytochrome electron transport pathway (ρ′V_cyt)predominated in supplying cell with ATP, PPP and alternative respiratory pathway (ρV_alt)perhaps played vital roles in Ⅲ stage.