TMT-Based Quantitative Proteomic Revealed Metabolic Changes of Jasmonic Acid in Regulating the Response of Malus baccata (L.) Borkh. Roots to Low Root-Zone Temperature

Malus baccata (L.) Borkh. is widely used as an apple rootstock in northern China. Previous studies have shown that jasmonic acid (JA) can alleviate the oxidative damage in M. baccata roots under low root-zone temperature (LT), yet the regulatory mechanism is unclear. To uncover the mechanism of JA in regulating the response of roots to LT, the differential expression of proteins was profiled using TMT combined with MRM. Of the 4979 proteins quantified, 403 differentially expressed proteins (DEPs) responded to the LT treatment and 264 DEPs responded to the JA + LT treatment. A bioinformatic analysis showed that protein processing in the endoplasmic reticulum, alpha-linolenic acid metabolism, and secondary metabolites play key roles in the regulation of JA in M. baccata roots exposed to LT. In addition, proteins involved in the stress response, such as peroxidases and calcium-dependent protein kinase, also participated in the regulation of JA. The quantitative data were then confirmed using MRM, thereby proving that the TMT results were reliable. The results can provide theoretical reference for the regulation of apple roots under low-temperature stress.