Plant regeneration from aged-callus of the woody ornamental species Lonicera japonica cv. "Hall's Prolific".

Callus cultures were initiated from in vitro grown leaf, stem and root segments of Lonicera japonica "Hall's Prolific", on a medium containing 10.7 μM α-naphthtylacetic acid and 2.7 μM benzyladenine, while media with 2,4-dichlorophenoxyacetic acid led to a rapid necrosis of explants. Shoot regeneration from true-callus (i.e. without any part of the original explant) was achieved for the three different source tissues within 12 weeks. The highest rate of regeneration was obtained by using benzyladenine (4.4 to 44.4 μM) as the sole hormone in the medium. The regenerated shoots were readily elongated and rooted on the same medium as used for multiplication, and plantlets were subsequently transferred to greenhouse conditions, where nearly 100% of them were successfully acclimatized. This is the first example of plant regeneration from aged (≥6 month-old) true-callus of a woody ornamental species.