From endosperm to triploid plants: a stepwise characterization of the de novo shoot organogenesis and morpho-agronomic aspects of an ornamental passion fruit (Passiflora foetida L.)

The cellular and biochemical features associated with expression of pluripotency in endosperm cells during de novo shoot organogenesis, as well as the cytogenetic and morpho-agronomic features of regenerated Passiflora foetida triploid plants has been recently reported. Endosperms were cultured on Murashige and Skoog medium supplemented with 0.5, 0.75, 1.0, 1.5, and 2.0 mg L−1 of 6-benzyladenine, thidiazuron, or kinetin. No plant growth regulators were added to the control treatments. Morphogenetic responses were observed only in the presence of cytokinins, especially thidiazuron. The highest percentage of morphogenetic responses (27%) and number of adventitious shoots per explant (68.2) were observed with 1.5 and 2.0 mg L−1 thidiazuron, respectively. The regeneration of adventitious shoots occurred mostly from the outer face of the endosperm by cells that acquired meristematic-like features. Lipids and proteins were consumed rapidly, whereas carbohydrates increased considerably throughout the organogenic process. Cytogenetic analyses confirmed the triploid genotype of endosperm-derived plants, whose vegetative and floral structures were nearly all larger than their diploid counterparts. This study provides a complete morphological characterization of P. foetida endosperm-derived triploid plants and opens new possibilities for genetic breeding of passion fruit. Triploid plants of Passiflora foetida originating from in vitro endosperm culture are morphologically distinct from their diploid counterparts.