Auxinic pulse induces direct somatic embryogenesis in Plinia peruviana (Poir.) Govaerts (Myrtaceae)

Plinia peruviana (Myrtaceae) is a fruit tree species endemic to Brazil with high importance to the food and pharmacological industries. Despite the need for vegetative propagation of selected genotypes for genetic breeding or fruit production, efficient propagation methods for the species have not yet been determined. This study aimed to advance the establishment of a protocol for inducing somatic embryogenesis from mature P. peruviana seeds. Three concentrations of 2,4-dichlorophenoxyacetic acid (10, 20, and 30 µM) in four auxinic pulses (1, 3, 5, and 7 days of exposure times) were tested. 20 µM and 30 µM of 2,4-D promoted the highest callogenesis (20–40 %), regardless of the exposure period, but calli did not present embryogenic potential. The formation of somatic embryos occurred asynchronously directly on the embryonic axes and was dependent on adding 2,4-D to the culture medium. The highest induction rate of direct somatic embryogenesis (26.7 %) was obtained using 20 µM of 2,4-D for 5 days of exposure. The light and electronic microscopic analyses allowed the characterization of the embryos at different stages of development and identified some abnormalities. Additional improvements to the protocol are still needed, including testing different culture media since no conversion and formation of complete plantlets was achieved.