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8. MOLECULAR PHYLOGENY OF THE GENUS LOLIUM
F. pratensis is the most prominent diploid representative, as the most common ancestor of
the genus Lolium. Moreover, Micropyropsis is considered to be in between owing to a subracemose
inflorescence, an intermediate trait between the paniculate of Schedonorus and
the reduced spike of Lolium. What is more, the difficulties in the separation of the genus
Lolium into two clades according to the mode of reproduction can be a further support of this
hypothesis.
8.4.2. Division of the genus Lolium into two groups – auto- and allogamous species
The division of the genus Lolium into two sections in accordance with the mode of
reproduction has long been postulated (Terrell 1968). The first section consists from
strict annuals, self-pollinated species, L. loliaceum, L. remotum, L. temulentum and
L. persicum, whereas out-pollinated L. perenne ssp. multiflorum, L. perenne ssp. perenne
and L. rigidum belong to the second section (Jenkin 1959). The above classification has been
confirmed in the majority of morphological and enzymatic studies (Loos 1993b; Charmet and
Balfourier 1994; Bennet et al. 2002). Molecular approaches employed in the present work
are in general agreement with the above picture. The genus can readily be divided into two
clades corresponding to whether the plants are autogamous or allogamous.
The first clade consists of three species, L. persicum, L. remotum and L. temulentum
that are self-fertile annuals, known only as weeds of cultivated crops. They possess unique
mtDNA haplotypes and a little different ITS region as demonstrated by the restriction digestions
of the LOLITS. Similarly to the other Loliums they have pollen allergen genes. Nevertheless,
the mean number of nucleotide substitutions differentiating their allergen encoding
genes from those observed in out-pollinated species is high and ranges from 0.237 to 0.255.
The low average genetic similarity between autogamous and allogamous species (I=0.398)
indicates a quite remote split between them. The second clade includes L. perenne ssp.
multiflorum, L. perenne ssp. perenne and L. rigidum that are wind-pollinated annuals, biennials
or perennials. They are easy to separate from all self-pollinated species due to different
morphology and DNA fingerprints revealed by the majority of DNA markers.
Nonetheless, the position of the fourth autogamous species, L. loliaceum is contradictory
with the current taxonomic classification according to which, the species should be
included in a single clade with L. persicum, L. temulentum and L. remotum. Conversely,
it consequently groups within out-pollinated taxa, in close proximity to multiflorum or
L. rigidum, yet being distinct from them. Similarly, less nucleotides are different when restriction
sites in L. loliaceum genes, both mitochondrial and allergen genes are compared
with out-pollinated species than if such comparisons are made between L. loliaceum and
self-pollinated taxa. The data from morpho-logical and isozyme analyses seem to confirm
the close relationships of L. loliaceum with outbreeders. Morphologically, it is in somehow
isolated position, more closely related to L. rigidum (Loos 1993a). Terrel (1968) interprets
L. loliaceum as an offshoot of L. rigidum. Isozymes place it together with multiflorum and
L. rigidum (Charmet and Balfourier 1994). The ability to separate L. loliaceum from the rest of
inbreeding species based on isozymes confirms its distinctiveness. Note, the other autogamous
species are unrecognisable at enzymatic level (Loos 1993b). Unfortunately, attempts
to clarify the evolution of L. loliaceum based on DNA data have been hampered by the fact