HPLC-MS/MS-based and transcriptome analysis reveal the effects of ABA and MeJA on jujube (Ziziphus jujuba Mill.) cracking

Fruit cracking is a physiological disease that occurs during the development of jujube, abscisic acid (ABA) and jasmonic acid (JA) mainly regulate the cell wall metabolic pathway and induce fruit cracking. Here, we used high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) to detect phytohormone-related metabolites at different developmental stages in cracking-susceptible (CS-15) and cracking-resistant (CR-04) individuals of full-sibling hybrid offspring. The fruit of ‘Pingshunbenzao’ jujube was treated with ABA and MeJA at the white-ripening stage, and the 48-h fruit cracking index was significantly increased compared to that of CK (water). Furthermore, RNA-seq of semi-red stage fruits identified several differentially expressed genes, related to the cell wall, such as SBT1.7 (Contig21.0.484), EXPA (Contig12.0.7) and QRT3 (newGene_1935), and transcription factors (TFs). These results reveal the relationship between the levels of different hormones and fruit cracking, identify genes associated with fruit cracking, and provide new insights to solve the problem of fruit cracking through hormonal regulation.