Melatonin treatment slows postharvest blueberry softening
image: Effects of MT treatments at different concentrations on (a) fruit firmness and (b) flesh firmness of blueberry fruit during room temperature storage.
Credit: Plant Hormones
A research team has found that spraying harvested blueberries with melatonin helps them stay firm during storage. In laboratory tests, the treatment slowed the breakdown of pectin, a structural component of fruit cell walls, while reducing the accumulation of abscisic acid (ABA), a plant hormone associated with softening. Treated berries also retained more indole-3-acetic acid (IAA), an auxin involved in fruit development. The findings point to a possible approach for preserving blueberry texture during handling and distribution, although its performance under commercial storage conditions remains to be tested.
Blueberries are valued for their flavor and nutritional qualities, but they soften after harvest as enzymes dismantle their cell walls. Previous studies have shown that melatonin can help preserve fruit quality and that ABA is linked to blueberry softening. IAA may also influence ripening through its interactions with ABA. What remained unclear was how a postharvest melatonin treatment affects both hormone pathways in blueberries, and whether those changes coincide with slower cell wall breakdown.
A study (DOI: 10.48130/ph-0026-0012) published in Plant Hormones on 08 June 2026 by Qian Zhou's team, Shenyang Agricultural University, reports that melatonin-treated blueberries softened more slowly while accumulating less ABA and maintaining higher IAA levels than untreated fruit.
The team selected uniformly mature ‘Bluecrop’ blueberries and sprayed them with melatonin solutions of 50, 100 or 150 micromoles per liter, or with a control solution. After treatment, the fruit was stored at approximately 20 °C, and firmness was measured during storage. All groups gradually softened, but the 100-micromole treatment preserved firmness most effectively; the researchers therefore used that concentration for the subsequent analyses. To examine what was happening in the cell walls, they measured insoluble and soluble pectin and the activities of four enzymes involved in cell wall degradation. Compared with control fruit, treated berries retained more insoluble pectin and generally contained less soluble pectin, consistent with slower pectin breakdown. The activities of polygalacturonase, β-galactosidase, β-glucosidase and endocellulase were also lower at key points during storage. Gene expression tests showed reduced activity of several genes associated with cell wall metabolism. The researchers then measured ABA and IAA and examined genes involved in their production, breakdown and signaling. ABA levels rose during storage in both groups but remained lower in the melatonin-treated fruit. In those berries, genes associated with ABA production, including VcNCED1 and VcNCED6, generally showed lower expression, while the ABA breakdown gene VcCYP707A showed higher expression at certain time points. Several ABA signaling genes were also downregulated, whereas VcPP2C, a negative regulator of ABA signaling, was upregulated. Meanwhile, IAA declined more slowly in treated fruit, which generally maintained higher IAA levels than the control. Melatonin also increased the expression of several IAA response genes, although one gene examined, VcIAA27, showed no significant treatment effect. A correlation analysis linked higher ABA levels with lower firmness and greater activity of cell wall-degrading enzymes. Together, these measurements describe a coordinated shift in fruit texture, hormone levels, enzyme activity and gene expression, but they do not establish every step of the proposed hormone interaction.
The study suggests that melatonin may delay blueberry softening by limiting cell wall degradation alongside changes in ABA and IAA regulation. It offers a molecular explanation for the firmness observed in the treated fruit and a basis for further preservation research. The experiments used one blueberry cultivar under controlled room-temperature storage; future work could test other cultivars and storage conditions and directly investigate how the two hormone pathways interact.
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References
DOI
Original Source URL
https://doi.org/10.48130/ph-0026-0012
Funding information
This study was funded by the Liao Ning Revitalization Talents Program (Grant No. XLYC2403139), and the China-Chile Belt and Road Joint Laboratory on Blueberry (Grant No. 2024021198-JH2/1021).
About Plant Hormones
Plant Hormones (e-ISSN 3067-221X) is an open access, online-only, academic journal publishing rigorously peer-reviewed original articles, reviews, break-through methods, editorials, and perspectives on broad aspects of plant hormone biosynthesis, signal transduction, and crosstalk. The journal primarily publishes fundamental research that represents significant advances or new insight into specialized areas of plant hormones, and review articles that provide comprehensive and critical review of current research areas and offer directions or perspectives for future research. The journal publishes applied research that has significant implications for the development of agriculture, horticulture, and forestry. Plant Hormones also provides a community forum by publishing editorials and perspective papers for expressing opinions on specific issues or new perspectives about existing research on particular topics. Plant Hormones is hosted by Chongqing University, and published by Maximum Academic Press.