Objective:To investigate the chromosome karyotype variation and evolution of Elymus dah-uricus and Elymus nutans and provide cytological data for the classification and evolution of Elymus.Methods:The chromosome karyotype of six populations of E.dahuricus and five populations of E.nu-tans from Northwest Sichuan Plateau were analyzed by dropping method.Results:The karyotype for-mula of populations D3057(3 057 m)and D2682(2 682 m)of E.dahuricus was 2n = 6x = 42 = 42m(1B),and population D2384(2 384 m)was 2n = 6x = 42 = 42m(4sat),with the 1A karyotype type.The karyotype formula of D2143(elevation 2 143 m)and D1747(elevation 1 747 m)are 2n = 6x = 42 = 40m + 2sm,with the 1B karyotype type.The karyotype formula of D1589(elevation 1 589 m)is 2n = 6x = 42 = 36m + 6sm,with the 2B karyotype.The karyotype formula of populations Y2126,Y2117 and Y2291a of E.nutans were 2n = 6x = 42m.The karyotype formula of population ZY3034 was 2n = 6x = 40m + 2m,and the karyotype formula of population Y2122 was 2n = 6x = 40m + 2sm.The karyotypes of five populations were 1B.Based on karyotype symmetry and evolution index,the population D1589(1 598 m)of Elymus dahuricus had the highest degree of evolution.The population Y2117(3 800 m)of Elymus nutans had the highest degree of evolution.Conclusion:There was abun-dant variation of karyotype in populations of Elymus dahuricus and Elymus nutans from different alti-tudes of Northwest Sichuan Plateau,which enhanced its adaptability to environment.
维普
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