Identification of retrotransposon families and analysis of their transcriptional activation in wheat

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 clarifyretrotransposon family structure and their evolution in wheat genome. RT-PCR was conducted by usingprimers based on the conserved RT pep-tide motifs of plant retrotransposons to amplify the RT domainof retrotransposons in the seedlings of wheat line Pm97034 treated with powdery mildew fungus. Highlevel of heterogeneity was detected in 51 (RT1-51) clones randomly selected and the identity ofnucleotide sequence among them ranged from 75.4 percent to 97.9 percent. These sequences, incombination with previously identified seven representatives from wheat retrotransposon families(families 1-7), were used to construct a composite phylogenetic tree. Three new families, designatedfamily 8 to family 10, were identified. Famliy 8 formed before divergence of the Pooideae subfamilyand was regarged as an ancient retrotransposon family. Some members of family 4 and family 7 hadtranscriptional activativity, and were present with multiple copies in wheat and its relatedspecies.