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Variations in the reverse transcriptase (RT) domain were analyzed to clarify retrotransposon family structure and their evolution in wheat genome. RT-PCR was conducted by using primers based on the conserved RT pep- tide motifs of plant retrotransposons to amplify the RT do- main of retrotransposons in the seedlings of wheat line Pm97034 treated with powdery mildew fungus. High level of heterogeneity was detected in 51 (RT1-51) clones randomly selected and the identity of nucleotide sequence among them ranged from 75.4% to 97.9%. These sequences, in combina- tion with previously identified seven representatives from wheat retrotransposon families (families 1―7), were used to construct a composite phylogenetic tree. Three new families, designated family 8 to family 10, were identified. Famliy 8 formed before divergence of the Pooideae subfamily and was regarged as an ancient retrotransposon family. Some mem- bers of family 4 and family 7 had transcriptional activativity, and were present with multiple copies in wheat and its re- lated species.
Variations in the reverse transcriptase (RT) domain were analyzed to clarify retrotransposon family structure and their evolution in wheat genome. RT-PCR was conducted by using primers based on the conserved RT pep- tide motifs of plant retrotransposons to amplify the RT do-main of the retrotransposons in the seedlings of wheat line Pm97034 treated with powdery mildew fungus. High level of heterogeneity was detected in 51 (RT1-51) clones randomly selected and the identity of nucleotide sequence among them ranged from 75.4% to 97.9%. These sequences, in combina- tion with previously identified seven representatives from wheat retrotransposon families (families 1-7), were used to construct a composite phylogenetic tree. Three new families, designated family 8 to family 10, were identified. Famliy 8 formed before divergence of the Pooideae subfamily and was regarged as an ancient retrotransposon family. Some mem- bers of family 4 and family 7 had transcriptional activativit y, and were present with multiple copies in wheat and its re- lated species.