Identification and Characterization of Reverse Transcriptase Domain of Transcriptionally Active Retrotransposons in Wheat Genomes.

To clarify activation characterization of wheat (Triticum aestivumL.) retrotransposons, transcriptionally activeTy1-copiaretrotransposons were found in wheat by using RT-PCR to amplify the RT domain. Sequence analysis of random RT-PCR clones reveals thatTy1-copiaretrotransposons are highly heterogeneous and can be divided into at least four groups, which are tentatively named TaRT-1 to TaRT-4. Dot blot hybridization indicates that TaRT-1 exists in the wheat genome as multiple copies (at 30 000 copies/ a hexaploid genome (ABD)). Northern blot hybridization showed that TaRT-1 is only expressed at a low level under normal conditions in seedlings, but at a high level when induced by powdery mildew fungus, jasmonic acid (JA) and salicylic acid (SA). These results suggest that the TaRT-1 expression is highly sensitive to biotic and abiotic stresses.(Managing editor: Li-Hui ZHAO) [ABSTRACT FROM AUTHOR]