Hybridization potential between the rubber dandelion Taraxacum
kok-saghyz and common dandelion Taraxacum ofﬁcinale
Department of Horticulture and Crop Science, Ohio Agricultural Research and Development Center,
The Ohio State University, 1680 Madison Avenue, Wooster, Ohio 44691 USA
Citation: Iaffaldano, B., J. Cardina, and K. Cornish. 2018. Hybridization potential between the rubber dandelion
Taraxacum kok-saghyz and common dandelion Taraxacum ofﬁcinale. Ecosphere 9(2):e02115. 10.1002/ecs2.2115
Taraxacum kok-saghyz (TK) is a species of dandelion that is of interest commercially for the
high-quality rubber produced in its roots; however, TK competes poorly with weeds. In order to overcome
this shortcoming, there is interest in developing herbicide-resistant TK germplasm by a variety of means,
including selection, transgene insertion, and gene editing. The potential release of such germplasm raises
the question of gene ﬂow between TK and its ubiquitous weedy relative, the common dandelion, Tarax-
acum ofﬁcinale (TO). The potential for introgression may be inﬂuenced by the reproductive biology of TO,
which can exist as a diploid sexual or polyploid obligate apomict. In North America, only polyploid,
apomictic TO has been described. As weedy TO types exhibit obligate apomixis, they are expected to be
unreceptive to TK pollen; however, it may still be possible for them to pollinate TK. To this end, unidirec-
tional crosses were conducted and progeny were evaluated with molecular markers. Taraxacum ofﬁcinale
pollen used to fertilize TK ﬂowers produced low seed set and seeds with a low germination rate. However,
23% of rare viable progeny proved to be the result of true hybridization. Outdoor TK seed production
areas heavily contaminated with TO were also screened for naturally occurring hybridization during a
three-year period using a combined strategy of both phenotyping (~3.35 million plants) and genotyping.
Hybrids were detected during one of these years, at a rate of 1 in 100,000, when pollination was augmented
with beehives. Hybrids from controlled crosses exhibited TO characteristics, such as lacerate leaves and
apomixis. Some apomictic hybrids were able to produce viable seeds, whereas non-apomicts were sterile.
Seeds produced by apomictic hybrids demonstrated the ability to establish and produce apomictic progeny
when in competition with perennial ryegrass. The prevalence of apomixis in TO may limit subsequent pol-
len-mediated gene ﬂow and introgression, but more work is needed to understand the longevity of
apomictic hybrids under natural conditions.
Key words: gene ﬂow; hybridization potential; rubber; Taraxacum kok-saghyz; Taraxacum ofﬁcinale.
Received 30 October 2017; revised 11 January 2018; accepted 18 January 2018. Corresponding Editor: Debra P. C. Peters.
Copyright: © 2018 Iaffaldano et al. This is an open access article under the terms of the Creative Commons Attribution
License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Natural rubber is an essential resource that is
commercially produced by the Brazilian rubber
tree (Hevea brasiliensis). Rubber tree cultivation
is restricted to tropical regions, requires labor-
intensive tapping, and is threatened by several
fungal diseases, including the fatal South Ameri-
can leaf blight (Edathil 1986). Moreover, to meet
growing rubber demands, it is estimated that
millions of hectares of biodiverse tropical forest
will be supplanted (Warren-Thomas et al. 2015).
Potential alternative sources of natural rubber
include the desert shrub, guayule (Parthenium
argentatum), and Kazakh dandelion (Taraxacum
kok-saghyz, TK, rubber dandelion). The use of TK
as a rubber-producing crop may be advantageous,
as it can be grown as an annual in temperate