Improved high-efficiency protocol for somatic embryogenesis in Peach Palm (Bactris gasipaes Kunth) using RITA® temporary immersion system

• Different culture system affects somatic embryo total protein and starch contents.
• Different culture system affects ADH activity and DNA global methylation rate.
• Abscisic acid promotes the maturation of peach palm somatic embryos.
• The in vitro culture system affects the somatic embryo regenerative efficiency.

Bactris gasipaes Kunth (Arecaceae) is an Amazonian palm cultivated mainly for the production of fruits and heart of palm. Biotechnological tools based on somatic embryogenesis (SE) can be used for improvement and germplasm conservation of this species. The efficiency of different culture systems and culture medium composition were evaluated to optimize the efficiency of SE. The study also evaluated global DNA methylation levels, total protein and starch contents, and alcohol dehydrogenase (ADH) activity. The RITA® bioreactor showed enhanced multiplication of somatic embryos with increased protein, starch levels and ADH activity. Furthermore, a low DNA global methylation rate (27.52%) was observed, suggesting its relationship with the expression of proteins associated with the maturation of somatic embryos and their subsequent conversion to plantlets. Somatic embryo maturation was successfully achieved on Petri dishes and abscisic acid (ABA) supplementation in the culture medium. Chlorophyll pigmented somatic embryos were obtained in Petri dishes containing PGR-free culture medium, and RITA® provided the greatest number of plantlets to be acclimatized after reaching 6–7 cm in length. In the acclimatization step, the best results were obtained with plantlets derived from RITA® after reaching 6–7 cm in length. These new findings shed light on the importance of defining adequate culture systems for different steps of in vitro regenerative protocols and represent a breakthrough in the in vitro morphogenesis process of peach palm, resulting in a large number of somatic plantlets with enhanced physiological and morphological features.

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