Somatic embryogenesis from mature zygotic embryos of commercial passionfruit (Passiflora edulis Sims) genotypes

Abstract

Mature zygotic embryos of three genotypes of Passiflora edulis Sims, including ‘FB-100’, ‘FB-200’, and ‘FB-300’ were incubated on a Murashige and Skoog (MS) (1962) medium supplemented with different concentrations (18.1–114.8 μM) of 2,4-diclorophenoxyacetic acid (2,4-D) and 4.4 μM of 6-benzyladenine (BA). MS basal medium and MS with BA induced germination of P. edulis embryos. The highest frequencies of embryogenic calli were observed when explants were incubated on MS medium supplemented with 72.4 μM 2,4-D and 4.4 μM BA for ‘FB-200’, which showed the highest potential for embryogenic callus formation. Cytological and histological analyses of pro-embryogenic callus revealed two distinct cell types: thin-walled, small, isodiametric cells with large nuclei and dense cytoplasm, typical of intense metabolic activity; and elongated and vacuolated cells, with small nuclei and less dense cytoplasm. Differentiation of somatic embryos was promoted on MS medium supplemented with activated charcoal and indole-3-acetyl-l-aspartic acid (IAA-Asp) either with or without 2,4-D. However, no conversion of somatic embryos into plantlets was observed.