Shining light on anther culture, a poorly understood regeneration route in passion fruit (Passiflora gibertii N. E. Brown): histological, hormonal, and phytochemical aspects

Plant regeneration from reproductive organs is a poorly understood route in passion fruit. The present study provides a morpho-hystological description of somatic embryogenesis from anther culture in Passiflora gibertii N. E. Br., as well as a phytochemical profile and genetic analysis of ploidy in the generated embryos. Flower buds were collected during the pre-anthesis period. Murashige and Skoog culture medium was supplemented with 2,4-dichlorophenoxyacetic acid and 6-benzyladenine. Embryogenic calluses were collected at different ages for histological, biochemical, and genetic evaluation of their ploidy. Anatomical characterization revealed the cell layers of the epidermal tissue involved in morphogenic events. Specifically, regions of intense cell division led to embryo formation and its subsequent regeneration. Moreover, as shown by hormonal and secondary compounds’ profiles, these regions were characterized by the presence of reserve compounds and higher levels of proteins and pectins. Finally, flow cytometry confirmed the diploid nature of the embryos. The present results define a pioneering study of anthers in P. gibertii N. E. Brown, and could serve as a blueprint for future in vitro regeneration protocols.