|Authors: ||R. Freyre, Zhanao Deng|
|Keywords: ||Caladium ×hortulanum, interspecific hybridization, new cultivar, Ruellia simplex, sterility, tetraploid induction|
Florida is among the largest producers of ornamental plants in the United States, therefore ornamental plant breeding is a major programmatic area in the Department of Environmental Horticulture at the University of Florida (UF). Currently, the UF ornamental plant breeding program focuses on improving approximately a dozen tropical and subtropical plants important to Florida.
Among them are Ruellia and Caladium.
Ruellia simplex (R. brittoniana, R. tweediana or Mexican petunia) is a popular landscape plant in southern states in the USA. However, this introduced plant has escaped cultivation and become invasive in natural areas.
Currently, only one sterile cultivar with tall habit and purple flowers exists.
Since 2007, the breeding objective at UF has been to develop sterile cultivars in other flower colors such as pink, white, white with a purple corolla tube, and potentially different growth habits such as tall and dwarf.
Breeding approaches are ploidy manipulations and hybridizations.
In 2011, selected breeding lines of R. simplex were evaluated in replicated field trials in four locations in Florida for landscape performance and sterility.
One purple, one pink and one white breeding line have been selected for potential cultivar release.
The primary objectives of Caladium breeding have been to develop new cultivars with novel leaf colors or coloration patterns, improved tuber yield, better resistance to soil-borne diseases, and enhanced tolerance to sun burn damage.
Over the last seven years, 13 new cultivars have been released in the fancy- and lance-leaved groups.
Efforts are being made to apply molecular markers to Caladium breeding.
Ninety-nine SSR markers have been developed from mining enriched genomic sequences, and these markers have proven very powerful in discriminating cultivars and revealing genetic relations among cultivars.
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