Registration and modeling of introgressive processes in mixed and isolated populations of Elymus gmelinii and E. pendulinus (Poaceae: Triticeae) in the southern Primorye Territory (Russia)

This study aimed to evaluate the possibility of introgression between the StYgenomic species Elymus gmelinii and E. pendulinus in mixed populations using hybridization and molecular markers. Analysis of ISSR markers from individuals grown from seeds collected in natural populations revealed the presence of cross-specific markers in some plants. To test for introgression potential, we generated a series of interspecific hybrids between Primorye Territory biotypes of the two species. Seed fertility stabilization was demonstrated in these hybrids. Variability and specificity in sequences of the nuclear gene GBSS1 (waxy) were examined in the hybrid E. gmelinii BKA-2059 × E. pendulinus HAS-2075, compared to parental biotypes and reference samples. The data suggest that intragenic recombination occurred in an intron of the maternal genotype between the relatively closely related St1 and Y subgenomes. Overall, our findings support the delineation of E. gmelinii and E. pendulinus as distinct species. However, under the monsoon climate with higher humidity in southern Primorye Territory, E. gmelinii exhibits a shift from xerophytic Siberian habitats to the more mesophytic ecotopes characteristic of E. pendulinus, leading occasionally to shared habitats. This ecological convergence increases the likelihood of interspecific introgression and mutual enrichment of the species' gene pools.