Polyethylene glycol effects on somatic embryogenesis of papaya hybrid UENF/CALIMAN 01 seeds

Abstract

Among commercial fruits, papaya (Carica papaya L.) is notably one of the most common ones around the world. The aim of the current study was to establish a somatic embryogenesis protocol for the hybrid UENF/CALIMAN 01, elucidating the effects of sucrose and 2,4-dichlorophenoxyacetic acid (2,4-D) on the induction of embryogenic cultures and the effect of polyethylene glycol (PEG) on somatic embryo maturation. Immature zygotic embryos of C. papaya hybrid UENF/CALIMAN 01 were cultured in MS culture medium supplemented with different concentrations of sucrose (30 and 60 g L-1) and 2,4-D (0, 20, 40 and 80 µM). The combination of 30 g L-1 sucrose and 20 µM 2,4-D resulted in the highest induction rates and the largest callus diameters. Furthermore, this combination was associated with the greatest potential to form somatic embryos. To promote maturation, cultures were inoculated in MS medium and exposed to different concentrations of PEG (0, 30 and 60 g L-1). The 60 g L-1 PEG treatment group had the highest average for the number, maturation and conversion of somatic embryos that resulted in plantlets at the end of the process. The addition of PEG to MS medium led to increased protein synthesis. These results are unprecedented for C. papaya hybrid UENF/CALIMAN 01 as the current study demonstrates the development of somatic embryogenesis in this high quality hybrid.