BACKGROUND Peel color is an economically relevant trait that influences the appearance and quality of red pear, whose red color is due to anthocyanin accumulation. Prohydrojasmon (PDJ), which has similar effects to endogenous jasmonates, was developed as a commercial bioregulator, particularly to improve fruits coloring. However, little information is available about the effect of PDJ on pears. This study investigated the effects of preharvest PDJ treatments on color development, phenolic compounds accumulation, and related gene expression in the red pear cultivar ‘Nanhong’. The treatments were performed during the pre‐color‐change period by spraying 50 or 100 mg L−1 of PDJ on fruits. RESULTS Preharvest PDJ treatments had a significant effect on color development, without affecting other quality parameters such as total soluble solids and fruit acidity. Liquid chromatography–mass spectrometry analysis showed that concentrations of anthocyanins and flavonols were enhanced in the peel after PDJ treatments, particularly when a concentration of 100 mg L−1 was used, whereas those of hydroxycinnamates and flavanols were decreased. After PDJ application, the transcription levels of anthocyanin biosynthesis genes PAL, CHS, CHI, ANS, F3H, and UFGT were enhanced, especially under the higher PDJ concentration tested. In addition, anthocyanin accumulation in the peels of PDJ‐treated fruits was found to be positively correlated with the upregulation of the regulatory gene MYB114. CONCLUSION Preharvest treatments with PDJ could be a useful tool to improve fruits coloring and increase phenolic content in pear. These findings also improve our understanding of the molecular mechanisms associated with PDJ‐regulated anthocyanin accumulation in pear fruits.

Stone cells are sclerenchyma cells formed by deposition of lignin, which is the most significant factor limiting the quality of pears. Ca2+ was known to inhibit stone cells in pear fruits, but the underlying molecular mechanism remains unclear. Our study revealed that exogenous CaCl2 (Ca2+) treatment of “Nanguo” pear (Pyrus ussuriensis) suppressed the synthesis of lignin and stone cell production. We further analysed the transcriptomes using RNA-seq, identified a transcription factor, PuDof2.5, and its targets gene PuPRX42-like (lignin polymerase gene) expression decreased in CaCl2-treated samples, which are involved in suppressing lignin biosynthesis in pear fruit. PuDof2.5 was found to bind directly to the PuPRX42-like promoter and induced its transcription. Taken together, our results revealed that Ca2+ modulated the key lignin biosynthetic transcription factor PuDof2.5 to suppress stone cell production in pear fruits.