The genes that determine the colour and size of cherries

Fruit development and ripening are complex biological processes regulated by a dense network of genetic and biochemical signals that determine key traits such as size, firmness, and color.

Sweet cherry (Prunus avium) is a non-climacteric fruit, making these processes particularly interesting to study, as they occur under hormonal regulation that is less dependent on ethylene compared to other species, thus highlighting the central role of specific transcription factors.

The study presented here investigates the molecular mechanisms controlling cherry growth and coloration, focusing on the role of specific transcription factors during fruit development.

Gene expression analysis

The authors analyzed gene expression profiles across different developmental stages of the ‘Regina’ cultivar grown in Northern Greece, identifying two particularly relevant transcription factors: PaWRKY57 and PaNAC29.

Both show a marked increase in expression during the later stages of development, coinciding with fruit growth and the onset of coloration, suggesting a key role in ripening.

To verify the function of these genes, a transient gene silencing approach was applied during the “color break” stage, when the fruit begins transitioning from green to red. Transient gene silencing approach was applied during this phase.

Experimental results

The results show that reduced expression of PaWRKY57 and PaNAC29 leads to clear effects on fruit development: in particular, delayed coloration and reduced fruit size are observed. This demonstrates that both factors are required for proper ripening and growth.

From a biochemical perspective, silencing these genes leads to a significant reduction in anthocyanin accumulation, the pigments responsible for the characteristic red color of cherries.

This effect is linked to the direct regulation of genes involved in the flavonoid biosynthesis pathway, such as PaDFR and PaLDOX, which show reduced expression when PaWRKY57 and PaNAC29 are inhibited. Genes involved in the flavonoid biosynthesis pathway are directly regulated.

Growth and regulation

As a result, pigment production is compromised and fruit coloration is weakened. Beyond coloration, the study also highlights a role in fruit growth regulation.

In particular, PaNAC29 appears to be involved in cellular development processes and hormonal regulation. The data suggest a connection with abscisic acid metabolism and signaling, a key hormone in non-climacteric fruits that helps coordinate ripening, metabolite accumulation, and stress responses.

An important finding is that these transcription factors do not act in isolation but are part of a complex regulatory network that coordinates multiple biological processes. They integrate signals related to growth, secondary metabolism, and ripening, contributing to synchronizing fruit development with physiological and biochemical changes.

Conclusion

In conclusion, the study demonstrates that PaWRKY57 and PaNAC29 are central regulators of sweet cherry development, controlling both growth and coloration through the modulation of key genes and metabolic pathways.

These findings provide new insights into the molecular mechanisms of ripening in non-climacteric fruits and offer a valuable basis for future breeding strategies aimed at improving fruit quality in terms of color, size, and uniformity.

Source: Vaia Styliani Titeli, Michail Michailidis, Christina Skodra, Athanassios Dalakouras, Martina Samiotaki, Georgia Tanou, Christos Bazakos, Athanassios Molassiotis, Transcription factors PaWRKY57 and PaNAC29 regulate fruit color and growth during sweet cherry development, Plant Physiology, Volume 200, Issue 2, February 2026, kiaf647, https://doi.org/10.1093/plphys/kiaf647 

Image source: Stefano Lugli

Melissa Venturi
Ph.D. in Agricultural, Environmental, and Food Sciences and Technologies – Fruit Tree Physiology and Cultivation - Bologna, Italy

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