In Vitro Plant Tissue Culture: Means for Production of Passiflora Species

Abstract

Passiflora genus includes over 600 species native to tropical and subtropical areas of America, appreciated for the production of fruit and medicinal value. Their ornamental potential is especially appreciated in North America and in Europe. With the expansion of the flower trade and the use of secondary metabolites in the pharmaceutical industry, a need for the constant monopolization of new technologies and alternative in vitro techniques that allow to obtain a uniform, high quality material free of pests and diseases occurs. Passiflora’s tissue cultures began to be studied in 1966, raising more and more interest of researchers worldwide. Depending on the source and type of the explant, plant growth regulators, and the used genotype, direct and indirect organogenesis are the main regeneration pathways for Passiflora. The latest approaches regarding the choice of explant and its source, the plant material surface sterilization and the specific requirements of each micropropagation stage are presented within our review. To this genus, the reduced gas exchange of in vitro growing of seedlings has been shown as the main cause of lack of success. In this regard, for regeneration and obtained improvements in morphogenesis, different protocols have been developed by using inhibitors of ethylene. In recent years, studies suggest that via somatic embryogenesis, starting from mature and immature zygotic embryos, regenerated plants that have maintained their mother plant ploidy can be successfully obtained. This confirms the callus cultures as main path to obtain in vitro regenerated Passiflora plants.