New development of Torenia
Torenia is an important summer bedding plant. The number of commercially available cultivars has increased during last decade, especially clone cultivars. Only three species have been used in the breeding program of Torenia whereas more than 40 species are recognized. This report provides an overview of recent technological advances in three respects: breeding, propagation and preservation of Torenia. Both mutation breeding and interspecific hybridization contributed to expand genetic variations and produced new cultivars in Torenia. Reciprocal crossings of 6 species, T. baillonii, T. bicolor, T. concolor, T. fournieri, T. hirsutissima, and T. siamensis, produced several new interspecific hybrids through ovule culture. Both backcross and self-pollination are useful to expand phenotype variations in the interspecific hybrids. An efficient young plants production system is required because demand of bedding plants in the flower market is concentrated in the early spring. Leaf cutting is the most efficient and economical vegetative propagation method, although in vitro propagation is applicable in Torenia. Reliable preservation methods for both mother plants of clone cultivars and genetic resources are required. A new cryopreservation technique, the cryo-plate vitrification method, has been successfully applied in Torenia.
Fukai, S. and Laojunta, T. (2020). New development of Torenia. Acta Hortic. 1288, 51-58
bedding plant, breeding, cryopreservation, interspecific hybridization, leaf cutting