Effect of culture medium composition on somatic embryos induction and maturation of pineapple [Ananas comosus (L.) var. (Smooth Cayenne)]

Abstract

The cultivation of pineapple contributes 1.6% of the gross Ivorian national product (GDP). However, this crop is facing a severe production crisis due to the aging of the orchards. Revising this sector requires the rejuvenation of orchards with healthy and improved planting material. This work was conducted to study the conditions for the efficient in vitro production of restorative pineapple planting material by somatic embryogenesis. The effects of seven culture media consisting of a different combination of nitrogen sources (casein hydrolyzate, glutamine, and glycine), cytokinins (kinetin or BAP), and auxins (2,4-D or picloram) were tested on somatic embryos induction and maturation in pineapple. Results of the study revealed that EIM1 (EIM added with 3 mg.L-1 picloram, 0.05 mg.L-1BAP, 2 mg.L-1 glycine, 1000 mg.L-1glutamine, 100 mg.L-1casein hydrolyzate) and EIM5 (EIM added with 2 mg.L-1glycine, 100 mg.L-1casein hydrolyzate, 0.2 mg.L-1kinetin) media induced the highest numbers of embryogenic cells, i.e., 154 and 149 cells respectively. Further, the EIM5 medium was more embryogenic, with the most significant number of mature embryos (66 mature embryos), and allowed the observation of all embryonic maturation stages. Embryogenic cell induction in pineapple is thought to be controlled by a low NH4+/NO3- ratio in interactions with phytohormones. In the presence of 2,4-D, embryogenic cell maturation was improved by kinetin addition to the culture medium containing glycine and casein hydrolyzate.