Regeneration of Plants from Protoplasts of Lonicera Species (Honeysuckle)

Abstract

The genus Lonicera includes several shrubby and climbing species, belonging to the family Caprifoliaceae, which are among the most widespread ornamental climbers and shrubs in Europe (Wright 1983). Climbing honeysuckles are generally characterized by a great ornamental value, due to the color, fragrance, size, and abundance of their flowers, however, because of their climbing habit, these plants need a support to grow correctly. On the other hand, among the shrubby honeysuckle species, none possesses all the ornamental traits of climbing ones. It would hence be desirable to combine positive features from each group, particularly to obtain shrubby plants with large, colored, and scented flowers. Unfortunately, sexual crossing between climbing and shrubby species has proven difficult so far, because of incompatibility problems. Protoplast fusion, with the further recovery of novel somatic hybrids, appeared as a feasible alternative to overcome the existing barriers to sexual crossing. In addition, and as a bonus, the somatic hybrid plants possibly produced between shrubby and climbing honeysuckle genotypes may provide useful insights into the genetic determinism of the growth habit. In order to reach this goal, however, the establishment of efficient strategies for the isolation and culture of protoplasts and for the regeneration of plants from callus thus produced stands as a prerequisite, and experiments were undertaken in all these areas.