Pre-harvest Application of Prohydrojasmon Affects Color Development, Phenolic Metabolism, and Pigment-Related Gene Expression in Red Pear (Pyrus Ussuriensis)

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 as endogenous jasmonates, was developed as a commercial bioregulator, particularly to improve fruits coloring. However, little information is available about PDJ effect 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. LC-MS 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. This article is protected by copyright. All rights reserved.

Keywords: Anthocyanins; Pears; Phenolics; Prohydrojasmon.