Quantitative succinyl-proteome profiling of hickory (Carya cathayensis) during grafting process

Hickory (Carya cathayensis) is an poplar nut-producing tree with high economic value. To overcome its long juvenile phase, grafting was applied to accelerate the transition from vegetative phase to reproductive phase. Lysine succinylation, a newly identified post-translational modification (PTM), is associated with various cellular processes. However, the regulatory mechanism underlying grafting process of hickory has not been studied at the level of PTM. Here, 259 succinylation sites in 202 proteins were identified, representing the first comprehensive lysine succinylome in hickory. The succinylation is biased to occur on the cytosolic proteins of hickory, indicating an effect of succinylation on the activities of enzymes associated with cellular metabolism. Moreover, four conserved succinylation motifs were identified in the succinylated peptides. Comparison of two grafting stages of hickory revealed that the differential expressed succinylated proteins were mainly involved in sugar metabolism, carbon fixation, amino acid metabolism and plant-pathogen interaction. In total, seven heat shock proteins (HSPs) with 11 succinylation sites were identified, and all these HSPs were up-regulated during the grafting process of hickory. Our data suggested that succinylated HSPs might play a role in the tolerance of grafted hickory plants. Our data are basic resources for the functional validation of succinylated proteins and a starting point for investigations into the molecular basis of lysine succinylation in the grafting process of hickory.