A very efficient adventitious regeneration (shoot organogenesis) system for cranberry (Vaccinium macrocarpon Ait.) leaves was developed. A basal medium consisting of Anderson's rhododendron salts and Murashige and Skoog's (MS) organics, supplemented with 10.0 μM thidiazuron (TDZ) and 5.0 μM 2ip, was effective for adventitious regeneration from leaves for the five cranberry cultivars tested: 'Early Black', 'Pilgrim', 'Stevens', 'Ben Lear', and 'No. 35'. Parameters examined included: 1) varying combinations of three plant growth regulators (TDZ, 2ip, and NAA); 2) explant orientation (adaxial vs. abaxial side in contact with the medium); and 3) leaf position relative to the apical meristem from the source plant. Cultivars varied in regeneration frequency, but cultivar x growth regulator interaction was nonsignificant. With optimal treatment conditions, regeneration occurred on more than 95% of the explants, with 'Early Black' and 'Pilgrim' producing as many as 100 shoot meristems per explant. At all concentrations tested, NAA (as low as 0.1 μM) increased callus formation and significantly reduced regeneration. Emerging adventitious shoots were always observed on the adaxial side of the leaves regardless of explant orientation on the medium. Regeneration was much greater when the abaxial side was in contact with the medium, and was not related to leaf position on the source plants. Elongation of adventitious shoots began ≃2 weeks after transfer to the basal medium without growth regulators. Cuttings of elongated shoots rooted 100% both in vitro in the basal medium and ex vitro in shredded sphagnum moss. The high regeneration efficiency achieved by using this system will be very useful in the application of techniques, such as Agrobacterium- and particle bombardment-mediated transformation. Chemical names used: 1-phenyl-3-(1,2,3-thiadiazol-5-yl) urea (thidiazuron, TDZ); N6-(γ-γ-dimethyallylamino) purine (2ip); α-naphthaleneacetic acid (NAA).
All Science Journal Classification (ASJC) codes
- Shoot organogenesis
- Vaccinium macrocarpon