Gibberellin-responsive genes delay kiwifruit ripening by modulating ethylene and firmness

By applying the GA compound GA₃ to ‘Cuixiang’ kiwifruit, researchers discovered that the treatment not only retained fruit firmness and delayed sugar accumulation but also significantly reduced ethylene production, a major driver of ripening. The study identified eight AcDELLA genes in the kiwifruit genome and linked several of them to enhanced postharvest storability, offering potential genetic targets for improving fruit shelf life and reducing waste.

Kiwifruit is prized globally for its rich nutritional profile but poses challenges in postharvest storage due to its rapid softening and ethylene-driven ripening. As a climacteric fruit, its shelf life is limited by metabolic processes that accelerate once respiration and ethylene peaks are reached. Gibberellins (GAs), a class of phytohormones, are known to regulate plant development and have been used to delay fruit senescence in various species. DELLA proteins, negative regulators of GA signaling, have been extensively studied in model plants but not in kiwifruit. Due to these challenges, it is essential to investigate the GA-DELLA regulatory network to develop strategies for extending kiwifruit postharvest longevity.

A study (DOI: 10.48130/ph-0025-0005) published in Plant Hormones on 04 March 2025 by  Aidi Zhang’s team, Ludong University, uncovers how specific genes known as DELLA—key repressors in the gibberellin (GA) hormone signaling pathway—play pivotal roles in slowing the ripening of postharvest kiwifruit.

In this study, researchers treated ‘Cuixiang’ kiwifruit with 300 mg/L GA₃ and tracked physiological changes over a 25-day storage period. Kiwifruit samples were stored at room temperature (24°C), and key indicators such as firmness, sugar content (TSS), acid levels, ethylene production, and cell wall composition were monitored. Additionally, endogenous gibberellin content was quantified using UPLC-MS/MS, and eight AcDELLA genes (AcDELLA1–8 ) were identified from the kiwifruit genome, followed by gene expression analysis and correlation studies using qRT-PCR and statistical modeling. The results showed that GA₃-treated fruit maintained higher firmness throughout storage, with only a gradual decline from 67.01 N to 49.27 N over 15 days, compared to a rapid decline in untreated controls. TSS and ethylene production increased more slowly in GA-treated fruit, peaking later and at lower levels. GA₃ application also slowed the degradation of starch and cell wall materials, such as cellulose-bound pectin (CBP). At the molecular level, GA₃-treated fruit showed significantly higher endogenous GA₃ and GA₁ levels than controls. Genome analysis identified eight AcDELLA genes, all containing conserved motifs associated with GA signaling repression. Expression of AcDELLA3/4/5/6/8 was upregulated by GA₃ and correlated positively with firmness and negatively with ripening indicators like ethylene and sugar. In contrast, AcDELLA7 was associated with fruit softening and responded more to ripening cues than GA. These findings suggest that DELLA proteins, particularly AcDELLA3/4/5/8, play a critical role in delaying kiwifruit ripening via gibberellin signaling, offering new genetic targets for postharvest preservation strategies.

The findings offer promising applications in the postharvest fruit industry, particularly for climacteric fruits prone to rapid ripening and spoilage. By identifying specific AcDELLA genes that respond to GA₃ and are linked to ripening delay, breeders and biotechnologists can explore molecular or agronomic strategies to extend shelf life without compromising fruit quality. Furthermore, understanding the crosstalk between GA and ethylene signaling could help fine-tune ripening control protocols for other perishable fruits.

###

References

DOI

10.48130/ph-0025-0005

Original Source URL

https://doi.org/10.48130/ph-0025-0005

Funding information

This work was supported by the Natural Science Foundation of Shandong Province (ZR2023MC007), and the Key Research and Development Program of Shandong Province (2024TZXD004).

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.