Indirect somatic embryogenesis in Aspilia Africana (Pers.) C. D. Adams, and histological and ploidy stability analysis
摘要
Aspilia africana (Pers.) C. D. Adams is a widely used medicinal plant to traditionally treat many diseases in Africa, including diabetes mellitus, malaria, and cancer. Over the years, explosion of human population has led to increased use of A. africana for therapeutic and other purposes, remarkably decreasing its wild population and thereby necessitating cultivation. This study focused on developing an indirect somatic embryogenesis (ISE) method for A. africana from leaf explants. Effects of exogenous plant growth regulators (PGRs), adenosine 5-monophosphate (AMP), phytosulfokine-α (PSK), nicotinamide adenine dinucleotide (NAD), and silver nitrate (AgNO3) on induction and development of somatic embryos were investigated. Induction of embryogenic callus and somatic embryogenesis were best achieved in Murashige and Skoog (MS) medium fortified with 0.1 mg/L 2,4-Dichlorophenoxyacetic acid (2,4-D), 2.0 mg/L benzylaminopurine (BAP), and 6.634 × 10−4 mg/L NAD at 91.67 ± 8.33% response and 8.00 ± 1.62 somatic embryos per explant. Differentiation and maturation of somatic embryos was optimally attained (2.33 ± 0.49 cotyledonary embryos per explant) in MS medium fortified with 0.5 mg/L abscisic acid (ABA), 6.634 × 10−2 mg/L NAD, 2.0 mg/L AgNO3, and 9 g/L gelrite. Highest level of germination (35.71 ± 1.73%) and conversion to plantlets (24.00 ± 1.15%) were recorded in half strength MS medium augmented with 0.5 mg/L gibberellic acid 3 (GA3), 0.1 mg/L naphthaleneacetic acid (NAA), and 2.0 mg/L AgNO3. Histological and flow cytometry analyses confirmed ISE and the genetic similarity of regenerants to zygotic embryo plants, respectively. This is the first report on ISE in A. africana and it would offer an alternative technique for rapid and sustainable seedling production, breeding improvement, and conservation of A. africana.