Adventitious organogenesis via intermediate callus formation in representatives of Prunus, Pyrus and Rubus genera

Abstract

The paper presents evaluation of the influence of 30 combinations of plant growth regulators (PGRs) on induction of adventitious organogenesis from leaves of in vitro propagated shoots in 5 genotypes: sour cherry 'Cacanski Rubin', cherry rootstock Gisela 5, pear rootstock Pyrodwarf, blackberry 'Cacanska Bestrna' and raspberry 'Meeker'. Blackberry 'Cacanska Bestrna' showed the highest regeneration capacity (regeneration was induced with 12 PGR combinations, the highest regeneration frequency 41.7%), followed by sour cherry 'Cacanski Rubin' (9 PGR combinations, max. regeneration frequency 20.8%) and rootstocks Pyrodwarf (6 PGR combinations, max. regeneration frequency 12.5%) and Gisela 5 (3 PGR combinations, max. regeneration frequency 8.3%). Raspberry 'Meeker' displayed the lowest regeneration ability (1 PGR combination, 8.3%). Regeneration was mostly indirect via intermediate callus formation. Consistency and quantity of the formed callus were primarily determined by type and concentration of applied auxins. Two main types of callus were observed: hard, compact calli with nodular structures on the surface and soft, friable ones. In most of the genotypes evaluated, friable calli were rarely formed, with the exception of regeneration media containing 2,4-D where the formation of large amount of soft, watery and white or yellowish callus was noticed. Indirect regeneration occurred through hard, compact callus at cross-sectional area of leaf blade, mid vein and petiole, while it was never observed on intact parts of leaves including leaf edges.