In Vitro Adventitious Shoot Regeneration via Indirect Organogenesis from Inflorescence Explants and Peroxidase Involvement in Morphogenesis of Populus euphratica Olivier

The inflorescences as explants for rapid propagation in vitro remained unknown in Populus euphratica Olivier. Here, we reported that multiple shoots were initiation from calli of both male and female inflorescences. The optimum medium for shoot induction from male inflorescences was lactose sulfite medium containing 1.0 mg L −1 6-benzylaminopurine (BA) and 0.5 mg L −1 α-naphthalene acetic acid (NAA) or Murashige and Skoog (MS) medium containing 0.5 mg L −1 BA and 0.2 mg L −1 NAA. The optimum medium of shoot induction from female inflorescence calli was the MS medium containing 0.5 mg L −1 BA and 0.2 mg L −1 NAA. Rooting of regenerated shoots was obtained on 1/2 MS medium supplemented with 0.5∼1.0 mg L −1 indole-3-butyric acid (IBA) and the highest frequency rooting was on medium containing 0.5 mg L −1 IBA. No shoots were obtained on medium without BA and NAA. Peroxidase (POD) activity was measured by polyacrylamide gel electrophoresis during shoot induction and differentiation stages. The results showed that two bands of POD (2a and 2b) activity appeared lowest during the early 8 days at the dedifferentiation phase of leaves inducing calli, whereas POD 2a, 2b activity appeared to be increasing at the homeochronous dedifferentiation phase of inflorescence. Five most intensive bands, POD 1a, 1b, 1c, 2a, and ab, appeared in 8th and 28th days at the redifferentiation phase during shoot morphogenesis. These results demonstrated that the POD was involved in shoot morphogenesis from both leaf and inflorescence explants of Populus euphratica .