The availability of high-quality clonal rootstocks is one of the key prerequisites for producing healthy, high-performing plants for efficient sweet cherry cultivation.
However, the in vitro micropropagation of sweet cherry still faces several challenges, including high production costs, intensive labor requirements, and genotype-dependent responses.
A recent study evaluated the potential of SETISTM temporary immersion bioreactors as an alternative to conventional semi-solid culture media for the propagation of Prunus avium and Gisela 6 rootstocks. The findings highlighted significant advantages in terms of plant growth and production efficiency, while also identifying physiological aspects that still require optimization.
The aim of the study was to compare the two culture systems during the multiplication and rooting phases by evaluating both morphological and physiological and biochemical parameters.
SETISTM bioreactors operate through short cycles of shoot immersion in liquid medium alternating with aeration periods, thereby improving water and nutrient uptake compared with conventional culture systems while simultaneously reducing handling time and production costs.
The culture establishment phase yielded satisfactory results, with in vitro establishment rates of 56% for Prunus avium and 62% for Gisela 6. These values were also attributed to the collection of plant material during spring, a period associated with lower microbial contamination.
The most noteworthy differences, however, emerged during the multiplication stage.
Although no significant increase in the number of shoots was observed, the temporary immersion system promoted greater shoot elongation in both genotypes, with the effect being particularly evident in Gisela 6.
The Relative Growth Rate (RGR) was also higher in the bioreactor system, confirming its greater efficiency in supporting plant biomass development.
Shoots produced through temporary immersion also exhibited superior ex vitro rooting capacity compared with those propagated on semi-solid media.
Gisela 6 achieved a rooting percentage of 57%, compared with 16% under the conventional method, while Prunus avium increased from 10% to 44%.
Although these values remain below the levels considered desirable for large-scale commercial propagation, the results demonstrate that the SETISTM system can improve the functional quality of regenerated plant material and promote more successful acclimatization.
Physiological and biochemical analyses revealed a strong genotype-dependent response.
Gisela 6 maintained nearly unchanged levels of photosynthetic pigments, flavonoids, malondialdehyde (MDA), and proline under both culture systems, indicating good physiological stability.
In contrast, Prunus avium proved more sensitive to temporary immersion culture.
Shoots grown in the bioreactors exhibited reduced chlorophyll and carotenoid contents together with increased levels of markers associated with oxidative stress, changes attributable to the development of “hyperhydricity”.
This physiological disorder, characterized by excessive water accumulation within plant tissues, compromises normal shoot morphology and remains one of the major limitations to the application of temporary immersion systems.
According to the researchers, hyperhydricity could be mitigated by optimizing culture conditions, including immersion frequency and duration, bioreactor ventilation, and the balance of plant growth regulators, particularly cytokinins, whose excessive concentrations are often associated with the onset of this disorder.
Overall, the study demonstrates that SETISTM temporary immersion bioreactors represent a promising solution for the micropropagation of sweet cherry rootstocks, producing more vigorous shoots, faster growth, and improved rooting performance compared with traditional culture systems.
Nevertheless, further optimization of culture protocols according to the specific characteristics of individual genotypes remains essential to minimize the effects of hyperhydricity and fully exploit the potential of this technology for large-scale commercial nursery production.
Source: Baltazar, E., Correia, M., Lopes, T., Martins, J., Canhoto, J., & Correia, S. (2026). Sweet cherry rootstock micropropagation using SETISTM bioreactor: evaluation, challenges, and biochemical characterization of regenerated shoots. Plant Cell, Tissue and Organ Culture, 164(3), 68.
Image source: Stefano Lugli
Andrea Giovannini
PhD in Agricultural, Environmental and Food Science and Technology - Arboriculture and Fruitculture, University of Bologna, IT
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