Phylogenetic Relationships and Diversity in Leymus (Poaceae, Triticeae) Based on Simple Sequence Repeats Markers

Aims: The objective of the study was to investigate: (1) the Ns genome donor and elucidate the origins of the Xm genome of Leymus; (2) evaluate the phylogenetic relationships among these species.

Methodology: The CTAB (cetyltrimethylammonium bromide) procedure was used to extract total genomic DNA from fresh leaf tissue. A total of 150 pairs of SSR primers were tested to screen those produced polymorphic DNA bands to continue further analysis with Elymus species and 13 diploid perennial species as templates. The GS was used to construct a dendrogram via the unweighted pair group method with arithmetic average (UPGMA) and the SHAN (sequential, hierarchical, agglomerative, and nested clustering) routine in the NTSYS-pc program.

Results: The primers WMC475, WMC11 and QWM213 showed more expansion efficiency in the research. There were significant diversity and polymorphism between Leymus and related diploid Triticeae species based on SSR makers. The largest GS coefficient values between Pse. stipifolia and Elymus hystrix indicates that the genetic distance is the closest and has a closer genetic relationship. In clade I, the Leymus species formed a very wellsupported into a small distinct group (Ia) first. Specifically, L. racemosus, L. salinus, L. secalinus and L. triticoides were clustered closely.

Conclusion: Psathyrostachys juncea, Psa. huanshanica and Psa. fragilis (Ns genome) clustered together into clade I with Leymus species, which further illustrates Leymus that contains Ns genome is more closely related to Psathyrostachys. St genome and J genome did not participate in the origin of Leymus, and the genetic relationship and genetic distance of Leymus species are related to geographical distribution and environment.