• Silver nitrate and myo-inositol improve the in vitro regeneration capacity of Poinsettia. • Silver nitrate and myo-inositol synergistically affect poinsettia regeneration. • Endogenous hormonal homeostasis is essential for a high regeneration rate. • Ethylene accumulation in vitro poinsettia shoots induces leaf chlorosis. • Modulation of ethylene biosynthetic pathways inhibits leaf chlorosis. Conventional propagation of Euphorbia pulcherrima Willd is limited by low efficiency and long timelines, creating a need for improved in vitro regeneration strategies. In vitro direct adventitious shoot organogenesis is mediated by wounding and exogenous application of Plant Growth Regulators (PGRs), specifically, auxins and cytokinins, which facilitates the redifferentiation of somatic cells and development of new shoots, and thus has the potential to increase regeneration efficiency. This study systematically investigated the effects of silver nitrate (AgNO 3 ) and myo-inositol as growth adjuvants on in vitro regeneration of Euphorbia pulcherrima cv. Christmas Eve. Quantitative assessments of various concentrations revealed that these growth adjuvants significantly enhanced morphogenic potential. This phenotypic enhancement correlated with the transcriptional upregulation of key shoot regeneration regulatory genes and downregulation of ethylene biosynthesis genes, particularly under AgNO 3 treatment. Collectively, these findings suggest that the modulation of endogenous hormonal homeostasis driven by the expression or suppression of specific transcription factors serves as a primary determinant of cellular totipotency and subsequent cell fate transitions.
Pahnekolayi et al. (Sun,) studied this question.