Genome analysis of Elymus alatavicus and E. batalinii (Poaceae: Triticeae)

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Abstract
Elymus alatavicus (Drob.) A. Love and E. batalinii (Krasn.) A. Love were studied to determine (i) meiotic behaviour, (ii) the mode of reproduction, (iii) the relationship between the two species, (iv) genomic constitutions, and (v) the most logical taxonomic classification of both species. A series of F1 hybrids between E. alatavicus, E. batalinii, and six "analyzer" species were developed. Chromosome pairing was studied at metaphase I to identify genomic similarities or differences. The results showed that E. alatavicus and E. batalinii are caespitose, self-fertile allohexaploids (2n = 42) with the same genomic formula SSYYXX. The F1 hybrids between E. alatavicus and E. batalinii had complete pairing (21 bivalents) at metaphase I in 7% of the cells and almost complete pairing in the remaining cells. High chromosome pairing and partial fertility (4 seeds/plant) in the F1 hybrids shows that the two species are closely related. Hybrids were obtained between E. alatavicus or E. batalinii and the following "analyzer" species with known genomic formulas: Pseudoroegneria spicata (Pursh) A. Love, 2n = 14, SS; P. cognata (Hack.) A. Love, 2n = 14, SS; E. lanceolatus (Scribn. &Smith) Gould, 2n = 28, SSHH; E. trachycaulus1 (Link) Gould ex Shinners, 2n = 28, SSHH; E. mutabilis (Drob.) Tzvelev, 2n = 28, SSHH; and E. drobovii (Nevski) Tzvelev, 2n = 42, SSHHYY. Chromosome pairing in this series of hybrids demonstrated that E. alatavicus and E. batalinii contain an S and probably a Y genome plus an unknown genome, X, that may have been derived from Psathryostachys huashanica Keng or from Agropyron. Elymus alatavicus and E. batalinii are correctly classified in the genus Elymus.Key words: cytotaxonomy, Agropyron, meiosis, chromosome.