Phylogenetic analysis among Hystrix, Leymus and its affinitive genera (Poaceae: Triticeae) based on the sequences of a gene encoding plastid acetyl-CoA carboxylase

The phylogenetic relationships among Hystrix, Leymus and its relatives were investigated using the four separate data sets (exon, intron, intron + synonymous sites, TGRT element) of a single-copy gene encoding plastid acetyl-CoA carboxylase. All the species studied here have only one copy of Acc1 gene except Hystrix patula that has two copies, Hy. patula pla1 and Hy. patula pla2. Hy. patula pla1 was grouped with the St-genome species (excluded Elymus wawawaiensis), Thinopyrum bessarabicum and Lophopyrum elongatum. Hy. patula pla2 was clustered with E. wawawaiensis and Hordeum bogdanii. Hy. coreana, Hy. duthiei ssp. duthiei and Hy. duthiei ssp. longearistata are closely related to the species of Leymus. The species with same nucleotide acid compositions within the element form a group. It is concluded that: (1) Hy. patula contains the StH genomes; (2) Hy. coreana, Hy. duthiei ssp. duthiei and Hy. duthiei ssp. longearistata have the NsXm genomes; (3) the Xm genome in Leymus is different from the Eb and Ee genome; (4) Th. bessarabicum and Lo. elongatum are related to the Pseudoroegneria species. These results are consistent with those obtained from morphological and cytological studies. Therefore, the Acc1 gene is a potentially valuable source for phylogenetic analysis in Triticeae.