Bioreactor-induced adventitious shoot regeneration affects genotype-dependent morphology but maintains clonal fidelity in red raspberry

Abstract

Multiple buds and shoots were produced in vitro from leaf segments of Rubus idaeus L. (red raspberry) cultivars ‘Latham’, ‘Heritage’, ‘Festival’, and ‘Nova’. A liquid medium-containing bioreactor system combined with a gelled medium with 2.3–9.0 μM thidiazuron (TDZ) was used for bud and shoot regeneration. Shoot elongation was best in a medium containing 4.4 μM of 6-benzyladenine (BA). BA induced elongated shoots rooted in the bioreactor vessel containing the same medium but without any plant growth regulators. The growth and development of these tissue culture (TC) plants obtained from ‘Latham’ and ‘Festival’ raspberry cultivars were compared with those obtained by conventional root cuttings (RC), under field conditions. In the fourth and fifth years of growth, the TC plants produced more and longer canes and more berries with higher yield than those of RC plants in cultivar ‘Festival’ but not in ‘Latham’. However, simple sequence repeat (SSR) marker assay produced a homogenous amplification profile in the TC and donor control plants confirming the clonal fidelity of bioreactor-derived micropropagated plants in all four cultivars. Adventitious shoot regeneration in a bioreactor system containing liquid medium apparently induces the genotype-dependent juvenile branching characteristics. These juvenile branching characteristics favored enhanced vegetative growth and berry production but maintained clonal fidelity in micropropagated raspberries.