Plant regeneration of pansy (Viola wittrockiana) ‘Caidie’ via petiole-derived callus

An in vitro plant regeneration protocol for pansy (Viola wittrockiana) cultivar ‘Caidie’ from petioles was established as following: callus induction on a half-strength MS medium supplemented with 0.45 μmol l−1 2,4-d plus 8.9 μmol l−1 BA, callus subculture on medium F (1/2MS with 4.5 μmol l−1 2,4-d, 2.7 μmol l−1 NAA and 0.44 μmol l−1 BA) and then on medium T (1/2MS with 4.5 μmol l−1 2,4-d, 2.7 μmol l−1 NAA and 2.2 μmol l−1 BA), shoot regeneration on medium D3 (MS media supplemented with 2.9 μmol l−1GA3, 23.6 μmol l−1 AgNO3, 0.02% active charcoal and 4.5 μmol l−1 TDZ), shoot multiplication on medium M (half-strength MS medium containing NAA 1.1 μmol l−1, TDZ 9.1 μmol l−1 and GA3 8.7 μmol l−1), and then shoot elongation and rooting on medium R (MS medium supplemented with 1.1 μmol l−1 NAA and 1.1 μmol l−1 BA). Subculture on appropriate medium was found to be important for successful shoot regeneration.