34
the Ph1 gene in hybrids with allopolyploid wheat (Dvorak 1972 ; Dover and Riley
1972 ). Indeed, based on chromosome pairing in meiosis of F 1 hybrids between A.
muticum with B-chromosomes (that suppress pairing between homoeologous chro-
mosomes) and diploid species of Aegilops , Ohta ( 1991 ) concluded that A. muticum
is the closest relative of Ae. speltoides and as such, it should be placed in section
Sitopsis. Sallares and Brown ( 2004 ), who analyzed the transcribed spacers of the
18S ribosomal RNA genes, reached a similar conclusion. In-situ hybridization with
repeated DNA markers and C-banding patterns suggest that A. muticum occupies an
isolated position within Aegilops and might be closer to the Sitopsis species than to
others (Badaeva et al. 1996 ). These studies support Eig’s ( 1929b ) separation of A.
muticum into a separate genus.
Aegilops speltoides contains two forms, ligusica and aucheri , that differ mark-
edly in the structure of their seed dispersal unit, ligusica has the wedge type and
aucheri the umbrella type (Eig 1929a ). The two types grow sympatrically in mixed
populations and are totally inter-fertile (Zohary and Imber 1963 ). Based on the
structure of the dispersal unit, it is reasonable to assume that aucheri is a more
advance type than ligustica. Aucheri type developed independently from the other
Sitopsis species or alternatively, derived from hybridization of Ae. speltoides ( ligus-
tica type) with Ae. longissima or Ae. searsii.
Ae. searsii and Ae. caudata have identical chloroplast type (Alnaddaf et al.
( 2012 ) and the two species were found to be close to one another (Sliai and Amer
2011 ). Dvorak and Zhang ( 1992 ) and Sasanuma et al. ( 1996 , 2004 ) found close
relationship between Ae. caudata and Ae. umbellulata. Cytogenetic and phyloge-
netic studies of the four advanced species of Aegilops , caudata , comosa , umbellu-
lata and uniaristata , showed that the N genome of Ae. uniaristata is one of the most
advanced genome in the group and is closer to the U genome of Ae. umbelluata than
to the genomes of Ae. caudata and Ae. comosa (Sallares and Brown 2004 ; Badaeva
et al. 1996 ). PCR fragment polymorphism analyses of chloroplast genomes have
placed Ae. umbellulata and Ae. comosa closer to Ae. tauschii than to T. monococcum
and Ae. speltoides (Tsunewaki et al. 1996 ; Gandhi et al. 2005 ).
Based on variation in repeated nucleotide sequences, Dvorak and Zhang ( 1992 )
constructed a phylogenetic tree of the species of the Aegilop – Triticum group. The
tree obtained was consistent with many cytotaxonomical data on species relation-
ships in the genus. It clustered the two Triticum diploids, monococcum and urartu,
that have been shown cytogenetically to have a common genome (Dvorak 1976 ;
Chapman et al. 1976 ). Also the species of Aegilops section Sitopsis , that contain a
similar genome (Kihara 1954 ; Feldman et al. 1979 ; Yen and Kimber 1990 ) were
clustered together in the phylogenetic tree. Within section Sitopsis the separation of
Ae. speltoides from the remaining four species was consistent with the classifi cation
by Eig ( 1929a ), who placed on morphological grounds Ae. speltoides into subsection
Truncata and the other species into subsection Emarginata. [ Ae. searsii that was
described by Feldman and Kislev ( 1977 ) was also classifi ed in subsection Emarginata].
Pairing data in meiosis of inter-specifi c F 1 hybrids between these species (Kihara
1954 and reference therein; Feldman et al. 1979 ), and studies of starch gel electro-
phoresis (Brody and Mendlinger 1980 ), RFLP analysis (Giorgi et al. 2002 ) and study
M. Feldman and A.A. Levy