Elytrigia Desv. is widely distributed throughout the world and is represented with species of various levels of ploidy including diploids, tetraploids, hexaploids, octaploids, and decaploids. The distribution pattern of these ploidy levels, however, is not well-defined. In this study, the levels of ploidy for 64 accessions of Elytrigia from 25 countries were determined with microscopic procedures. The results showed that accessions of E. intermedia and E. repens were grouped into three distinct levels of ploidy including diploids, tetraploids and hexaploids. For E. elongata, E. pontica, and E. caespitosa, it was found that two ploidy levels presented, and only one ploidy level was in those of E. hybrid, E. pycnantha, E. pungens, E. juncea, and E. alatavica. Karyotype analysis indicated that the karyotype formula of diploid, tetraploid and hexaploid of E. intermedia was 2n = 2x = 14 = 6m + 6sm + 2st, 2n = 4x = 28 = 2M + 10m + 16sm and 2n = 6x = 42 = 4M + 18m + 20sm, respectively. Furthermore, the karyotype formula of three germplasms in tetraploid of E. intermedia was 2n = 4x = 28 = 2M + 10m + 16sm, 2n = 4x = 28 = 4M + 22m (sat) + 2sm and 2n = 4x = 28 = 4M + 12m + 12sm (sat), which were not completely uniform. Therefore, it could be suggested that the studies about chromosome constitution would be helpful for the detail understanding of the diversity of germplasm resource in Elytrigia and promoting the utilization in the crop molecular breeding.
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