Nodule Cultures of Paulownia x Taiwaniana

Nodule cultures with potential applications in regeneration strategies, automated micropropagation, and in vitro phytochemical production in many plants have been reviewed. The lst nodule cultures of Poulownia x taiwaniana were established and maintained for more than 1 y by regular subculturing. Vigorous callus clumps were induced from leaf explants cultured on 1/2MS medium containing 3 mg/L IBA and 3 mg/L BA. Nodule cultures were produced after leaf-derived calli were transferred into MS liquid medium containing 3mg/L each of IBA and BA, and placed on a reciprocal shaker at 130 rpm for 6 wk. Cell growth cycles of the 3 mo-old and 1-y-old subcultures were determined by using settled cell volume and electrical conductivity. Results obtained from these 2 measurements were consistent with each other. Conductivity appeared to be rapid, simple, and reproducible. Histological changes of cell differentiation and vascular organization were also investigated at different growth phases of cultures. Nodules maintained organogenic capability in the lst few subcultures, but lost it in successive cultures.