Successful in vitro germination of Rubus genotypes induced to polyploidy using three different antimitotic agents

M.F. Roque, V. Pergolotti, S. Sabbadini, C.S. Trindade, T. Valdiviesso, P.B. Oliveira, B. Mezzetti
Seed germination and polyploidy are the main challenges in a blackberry breeding program since seeds have deep double dormancy and Rubus has different levels of ploidy. Thus, polyploidization is considered as a valuable and fast breeding method to develop new cultivars with enhanced characteristics. In Portugal, a new breeding program, financed by a private company, was started in 2021 in collaboration with Portuguese and Italian researchers. In this study, open-pollinated seeds from three genotypes (R. fruticosus ‘Apache’ and ‘Sweet Royalla’, and R. occidentalis) were germinated in vitro by applying a cutting treatment and compared to uncut seeds. Data on germination efficiency and time of germination were acquired during the first 30 d from the treatment. Preliminary results showed high germination rates in R. occidentalis cut seeds (>92%) compared to the uncut control, which did not germinate. The optimization of the polyploidy-inducing protocol in the different genotypes consisted of treating the seeds with different antimitotic agents at increasing concentrations (colchicine at 0, 125, 150, 175, and 200 mg L‑1; oryzalin or trifluralin at 0, 5, 10, 15, and 20 mg L‑1), applied for different time durations (0, 24, and 48 h). Results showed that the transversal seed coat cutting treatment is the best for Rubus seed germination. In the polyploidy induction trial, the results demonstrate that ‘Apache’ had the highest germination rate at the lower concentrations of colchicine (125 and 150 mg L‑1) and oryzalin and trifluralin (5 and 10 mg L‑1). Reaction times showed a significant interaction with genotype and antimitotic agents.
Roque, M.F., Pergolotti, V., Sabbadini, S., Trindade, C.S., Valdiviesso, T., Oliveira, P.B. and Mezzetti, B. (2024). Successful in vitro germination of Rubus genotypes induced to polyploidy using three different antimitotic agents. Acta Hortic. 1388, 365-372
DOI: 10.17660/ActaHortic.2024.1388.53
Rubus, polyploidization, fast breeding, germination efficiency, antimitotic agents

Acta Horticulturae