Temperature is one of the most important factors affecting coloration during fruit ripening. We found that red color development and anthocyanin synthesis in the “Sanhua” plums were significantly inhibited at temperatures higher than 33°C, whereas softening and sugar accumulation in these fruits were similar to those at 25°C. There was a marked reduction in the expression levels of PsACO and PsACS at 33°C. A total of 78 different anthocyanin derivatives were identified among the 0 d, 2 d-25°C, 2 d-33°C, 4 d-25°C and 4 d-33°C via UPLC-MS/MS. The cyanidin-3-O-glucoside was the primary contributor to red pigmentation in the “Sanhua” plums, and the content of cyanidin-3-O-glucoside was lower at 33°C than that at 25°C. Transcriptome analysis revealed 691 differentially expressed genes (DEGs) in the 2 d-33°C vs 2 d-25°C and 824 DEGs in the 4 d-33°C vs 4 d-25°C, and DEGs were significantly enriched in metabolic and secondary metabolic pathways. The activity of enzymes and the expression of genes related to anthocyanin synthesis were suppressed at 33°C compared with those at 25°C. Moreover, nine transcription factors (TFs) were screened out, including AtMYB113-like, AtMYB44-like and MdWRKY41-like, as candidate regulators contributing to abnormal coloration in fruit in response to high temperatures, providing candidate targets for further in-depth investigation. These results provide a theoretical basis for the suppression effect of high temperatures on anthocyanin synthesis during fruit ripening of “Sanhua” plums in further research.
Chen et al. (Tue,) studied this question.