© Springer International Publishing Switzerland 2015 1
M. Molnár-Láng et al. (eds.), Alien Introgression in Wheat,
DOI 10.1007/978-3-319-23494-6_
Chapter 1
Taxonomic Treatments of Triticeae
and the Wheat Genus Triticum
Nadine Bernhardt
1.1 The Tribe Triticeae
The economically important grass tribe Triticeae Dumort. consists , depending on
taxonomic treatment , of about 360 species and several subspecies in 20–30 genera,
adding up to 500 taxa. Triticeae occur in temperate regions all over the Earth and
harbor the important cereals, bread wheat ( Triticum aestivum ), barley ( Hordeum
vulgare ), rye ( Secale cereale ) and their wild relatives, many forage grasses, species
crucial for soil stabilization, and important elements of diverse plant communities.
Morphologically they are characterized by the possession of open leaf sheath margins
on culm leaves, membranous ligules, infl orescences having sessile spikelets, and
ovaries with a hairy top. The tribe comprises annual as well as perennial species ,
with the annual members being most abundant in Western Asia and the Mediterranean,
while the highest species diversity for the perennial members is reported in Central
(and East) Asia, particularly China (Seberg and Frederiksen 2001 ; Barkworth and
von Bothmer 2009 ). There are self-pollinating as well as cross-pollinating species
(Escobar et al. 2010 ). Within Triticeae, all taxa have a chromosome base number of
x = 7 and 2n chromosome numbers are 14 or multiples of 14. Supernumerary or B
chromosomes are reported in only a few genera like Secale and seem to be a result
of major karyotype reorganizations (Martis et al. 2012 ). The genomes vary in size,
but are generally very large. For instance, the genome size of Triticum aestivum
amounts to more than 100 times of the genome size of Arabidopsis thaliana.
The tribe is of interest to many areas of research, including archaeology, domes-
tication research, crop breeding, and evolutionary biology. Approximately 12,
years ago, barley ( Hordeum vulgare ), einkorn wheat ( Triticum monococcum ), and
emmer wheat ( Triticum turgidum ) were domesticated in the Fertile Crescent in
N. Bernhardt (*)
Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Taxonomy & Evolutionary
Biology , Corrensstr. 3 , D-06466 Gatersleben , Germany
e-mail: [email protected]