91.8 Pros and Cons of Available Triticum Treatments:
Dorofeev et al. vs. Mac Key/van Slageren
On top of two different interpretations of the genus Triticum (i.e., keeping Aegilops
and Triticum separate vs. their unifi cation in one genus), there exist different and
incongruent taxonomic treatments for Triticum s.str. leading to confusion for the
international research community. A good classifi catory system for Triticum seems
pivotal not only to unravel its origin but also to effi ciently preserve its morphologi-
cal and genetic diversity. It was argued that, therefore, an especially detailed taxo-
nomic system is needed that also meets the needs for future wheat breeding
(Goncharov 2002 ; Goncharov 2011 ). Additionally, the lack of consistent rules of
how to treat natural and artifi cial hybrids resulted in many unnamed artifi cial hybrids
as well as hybrids with invalid names (Goncharov 2011 ).
There are two main opposing classifi catory systems, and both take into account
genomic data. On the one hand, there is the latest monograph from Dorofeev et al.
( 1979 ) that is based on a very fi ne discrimination of morphological characters, but
was also infl uenced by Flaksberger’s ( 1935 ) treatment founded on the division of
taxa into groups by ploidy level (diploids, tetraploids, and hexaploids). Dorofeev
et al. recognized 27 Triticum species in two subgenera, and no less than 1054 infra-
specifi c taxa. The subgenera are divided by the possession of different version of the
A genome ( A b^ vs. A u^ , Table 1.2 ). Species rank was given also to cultivated wheat.
This also accounts for cultivated wheat with only relict or locally restricted impor-
tance, e.g., T. compactum , T. macha , and T. spelta (van Slageren 1994 ). Although
well known, since it was written in Russian, the monograph was of limited access to
the global research community. A translation into English is expected to become
available soon (pers. comm. H. Knüpffer, Gatersleben).
On the other hand, Mac Key ( 1966 , 1977 , 1989 , 2005 ) formulated his concept
based on classical (Mendelian) genetics, i.e., observations made on a small number
of genes that play a role in the development of distinct morphological characters in
wheat (Goncharov 2011 ). In his most recent treatment, Mac Key ( 2005 ) recognized
ten species and 20 infraspecifi c taxa in four subdivisions. He defi ned the subdivision
Triticosecale for three intergeneric hybrid species of Triticum and Secale. The treat-
ment was acknowledged as an open system that allows adjustment (van Slageren
1994 ) or as a “plausible and workable concept” (Hammer et al. 2011 ). But it was
also criticized because of its simplicity. It was argued that it tends to overlook and
thereby exclude morphologically distinct entities from genetic resources (Goncharov
2011 ; Hammer et al. 2011 ). Nevertheless, treatments based on Mac Key have been
widely accepted (e.g., Petersen et al. 2006 ; Feldman and Kislev 2007 ; Matsuoka
2011 ). A detailed comparison of the nomenclatural relationships between Dorofeev
et al. ( 1979 ) and Mac Key ( 2005 ) can be found in Hammer et al. ( 2011 ). This pub-
lication also refers to other studies that applied a meticulous morphological treat-
ment or infl uenced Dorofeev et al. 1979 (e.g., Körnicke 1885 ; Percival 1921 ;
Vavilov 1925 ; Mansfeld 1951 ).
1 Taxonomic Treatments of Triticeae and the Wheat Genus Tr it icu m