Meta-Topolin-induced organogenesis in Sphagneticola trilobata (L.) Pruski via fascicular cambium activation and transverse thin cell layers
摘要
The present study demonstrates the role of meta-Topolin (mT) in activating fascicular cambial cell division and promoting organogenesis in transverse thin cell layer (tTCL) stem explants of Sphagneticola trilobata (L.) Pruski (family Asteraceae). The tTCLs were obtained from surface disinfected stem explants and cultured on Murashige and Skoog (MS) medium containing 1.5 mg L−1 mT. This concentration of mT successfully stimulated cell division in the cambial meristem. After 8 d of incubation, the parenchyma cells in the fascicular cambium (FC) showed an interconnected network of elongated cells, which differentiated into microshoots within 4 wk. The proliferation and growth of cells in the FC resulted in the development of adventitious shoot (AS) primordia, initiating new shoot formation. The number of shoots produced (5.0 ± 1.0 shoots per explant) on medium with 1.5 mg L−1 mT was significantly higher than with the same concentration of BAP (6-benzylaminopurine), yielding 3.0 ± 0.6 shoots per explant. Further proliferation of shoots on a medium containing 1.5 mg L−1 mT and 0.15 mg L−1 indole-3-acetic acid (IAA) increased the shoot count to 33.0 ± 2.1 per explant. The in vitro–grown shoots were then successfully rooted ex vitro in a greenhouse environment using soilrite with 150 mg L−1 indole-3-butyric acid (IBA), and the rooted plants were effectively acclimatized and transferred to field conditions. The genetic homogeneity of the in vitro–propagated plants was confirmed through start codon targeted (SCoT) molecular markers. This research provides novel insights into fascicular cambium–mediated organogenesis in S. trilobata, offering a promising approach for micropropagation and conservation of other Asteraceae members.