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Plant hormones are small molecules resulting from various essential metabolic pathways that play a critical role in the regulation of plant growth and development. The majority of plant species are the rich source of valuable bioactive compounds, where these compounds actively participate in various aspects of biosynthesis such as drugs, fragrances, flavor, dye, pigments, and pesticides. The dynamic role of bioactive compounds on a commercial scale surrounds the interest of the researchers and pharmaceutical industry. Therefore, it is a prerequisite to explore new species that produce these compounds beyond its flora. For this, several strategies were explored keeping the objective of bioactive compounds. In recent, the induction of adventitious roots by different PGRs and culturing the production of highly valuable compounds in several endangered plant species are practicing. The adventitious roots establish from cutting not only reduce pressure on natural populations but also helps in the conservation of these species and it can further be utilized for the production of bioactive compounds to up-scale the agricultural and pharmaceutical industries. Thus overall, these extinct species playing a beneficial role in our ecosystem as well as expand the area of new drug discovery for the welfare of human beings. Based on this limelight, the current review article focused on summarizing the application of plant growth regulator, especially auxin and cytokinin, and the progress made in the recent past in the area of initiation and establishment of adventitious root cultures for the production of bioactive compounds in laboratory conditions of biologically endangered and medicinally valuable species. [ABSTRACT FROM AUTHOR]

The effects of varieties, concentrations, and number of applications of plant growth retardants (PGRs) on the morphological, physiological, and endogenous hormones of Magnolia wufengensis L.Y. Ma et L. R. Wang were assessed to obtain the most suitable dwarfing protocol for M. wufengensis and to provide theoretical support and technical guidance for the cultivation and promotion of this species. One-year-old M. wufengensis 'Jiaohong No. 2' grafted seedlings served as the experimental materials. In the first part of the experiment, three PGRs (uniconazole, paclobutrazol, prohexadione calcium), three concentrations (500, 1000, 1500 ppm), and three applications (one, three, and five applications) were applied in dwarfing experiments to perform L9 (34) orthogonal tests. In the second part of the study, dwarfing experiments were supplemented with different high uniconazole concentrations (0, 1500, 2000, 2500 ppm). Spraying 1500 ppm uniconazole five times achieved the best M. wufengensis dwarfing effect, related indicators of M. wufengensis under this treatment were better than other treatment combinations. Here, M. wufengensis plant height, internode length, scion diameter, and node number were significantly reduced by 56.9%, 62.6%, 72.8%, and 74.4%, respectively, compared with the control group. This treatment increased superoxide dismutase (SOD) activity by 66.0%, peroxidase (POD) activity by 85.0%, soluble protein contents by 43.3%, and soluble sugar contents by 27.6%, and reduced malondialdehyde (MDA) contents by 32.1% in leaves of M. wufengensis compared with the control. The stress resistance of M. wufengensis was enhanced. The treatment also reduced gibberellin (GA3) levels by 73.0%, auxin (IAA) by 58.0%, and zeatin (ZT) by 70.6%, and increased (abscisic acid) ABA by 98.1% in the leaves of M. wufengensis. The uniconazole supplementation experiment also showed that 1500 ppm was the optimal uniconazole concentration. The leaves exhibited abnormalities such as crinkling or adhesion when 2000 or 2500 ppm was applied. Given the importance of morphological indicators and dwarfing for the ornamental value of M. wufengensis, the optimal dwarfing treatment for M. wufengensis was spraying 1500 ppm uniconazole five times. [ABSTRACT FROM AUTHOR]