Abstract
The genus
Brachypodium
is generally considered taxonomically difficult because of the high levels of phenotypic variation and frequent hybridization between its species. In this study, the patterns of genetic variation of 180 lines of
B. distachyon
(
B. distachyon, B Stacei
and
B. hybridum
) collected from diverse regions in Tunisia were investigated using 18 morpho-phenological traits and 15 SSR markers. Our results showed that the polyploid species
B. hybridum
is the most abundant in Tunisia. Moreover, considerable morphological variation was revealed for the majority of analyzed traits. The variation was found to be more pronounced within
B. hybridum
, than its two progenitors
.
Importantly, we found that
B. distachyon
was characterized by early maturity,
B. stacei
differed from the two other species by plant height, whereas the allotetraploid species was mainly characterized by traits related to biomass production. At the molecular level, the fifteen SSR marker were found to be very informative in terms of polymorphism and allelic diversity (
P
= 100%,
Na
= 20.3 and
Ne
= 10.8).
B. hybridum
was found to be much variable than
B. stacei
and
B. distachyon (He
= 0.86,
He
= 0.78 and
He
= 0.58, respectively). FCA and Bayesian clustering showed a clear separation between the three species, which suggests the high usefulness of SSR markers used in our study in the delimitation between
B. distachyon
,
B. stacei
and
B. hybridum
.