Why ethylene reddens some ‘Guifei’ mangoes but not others

A research team has found that postharvest ethylene treatment reddened ‘Guifei’ mangoes from Guangxi, China, but produced little color change in fruit from Hainan. The Hainan mangoes had much higher levels of gibberellic acid (GA₃), a plant hormone, and showed reduced activity in part of the pathway that produces red anthocyanin pigments. The findings could help growers and packers understand why the same treatment gives different results and guide future approaches to improving mango appearance after harvest.

Red peel is an important quality trait for ‘Guifei’ mangoes, and growers use ethylene releasing treatments to encourage color development. Ethylene can promote anthocyanin accumulation in some fruit, while gibberellins can either enhance or suppress coloration depending on the crop and conditions. Yet ethylene treatment does not reliably redden postharvest ‘Guifei’ mangoes. Researchers have lacked a clear explanation for this variable response, particularly how a fruit's existing hormone levels might affect the genes and enzymes responsible for making red pigments.

A study (DOI: 10.48130/ph-0026-0017) published in Plant Hormones on 29 July 2026 by Yuanzhi Shao's & Wen Li's team, Hainan University, reports that higher GA₃ levels were associated with a weaker coloration response to ethylene and reduced expression of a pigment regulating gene called MiERF105.

The team compared ‘Guifei’ mangoes harvested in Guangxi and Hainan, selecting fruit with similar initial appearance and maturity. At harvest, the Hainan fruit contained about ten times as much GA₃ as the Guangxi fruit, although their initial ethylene production did not differ significantly. For each origin, the researchers dipped one group of fruit in water and another in a 900 mg/L ethephon solution, which releases ethylene. They then tracked the fruit during storage, measuring hormone levels, peel color, pigments and activities of enzymes involved in anthocyanin production. Ethephon increased ethylene production in fruit from both regions. In Guangxi mangoes, it also increased peel redness and anthocyanin content while stimulating pigment related enzyme activities. Hainan mangoes, whose GA₃ levels remained comparatively high during storage, showed no significant improvement in coloration. Their ethephon treated fruit accumulated less anthocyanin than untreated controls. To investigate the molecular response, the team analyzed gene expression in Hainan mangoes using RNA sequencing and quantitative PCR. They found that ethephon treated fruit had lower expression of MiERF105 late in storage, alongside changes in genes involved in pigment synthesis. Laboratory binding tests showed that the MiERF105 protein attaches to the regulatory regions of MiPAL2 and MiANS3, two genes linked to anthocyanin production. Reporter experiments indicated that it activates both regions. When the researchers temporarily increased MiERF105 expression in mango slices, the tissue developed color faster and accumulated more anthocyanin. Together, these tests identify a route through which MiERF105 can promote pigment formation. They do not, however, establish that GA₃ directly suppresses this gene. Because the fruit came from different growing regions, other differences between them may also have contributed to their responses.

The study offers a molecular explanation for why an ethylene treatment that works on one batch of ‘Guifei’ mangoes may fail on another. It links high endogenous GA₃ with poor reddening and identifies MiERF105 as a promoter of anthocyanin production. The authors say that applying GA₃ or blocking its synthesis in future experiments will be necessary to test whether the hormone itself causes the reduced response. Such work could eventually support more reliable decisions about postharvest color treatments.

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References

DOI

10.48130/ph-0026-0017

Original Source URL

https://doi.org/10.48130/ph-0026-0017

Funding information

This work was supported by the Hainan Provincial Academician Innovation Platform Research Special Project (YSPTZX202516), the National Natural Science Foundation of China (32360778), and the National Key Research and Development Program of China (2023YFD2300803-7).

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.