Retrotransposons and ethyl methanesulfonate-induced diversity in hexaploid wheat and Triticale

The bulk of large plant genomes consists of retrotransposons. Retrotransposons are able to integrate into a multitude of loci in the genome, and can thereby generate insertional polymorphism between individuals, as well as mutations and new characteristics. Retrotransposons are largely quiescent during development, but become more active in response to biotic and abiotic stresses, which cause them to produce larger pools of transcripts. The present study assesses the structural dynamics and putative transcriptional activation of BARE-1 and WIS 2-1A retrotransposons in ethyl methanesulfonate (EMS)-induced hexaploid wheat and Triticale sphaerococcum mutants, via an RT-PCR approach that utilized the retrotransposon based markers SSAP, IRAP and REMAP. Our results demonstrate a polymorphic pattern distribution of BARE-1/WIS 2-1A members, and identify new insertions. The WIS 2-1A retrotransposon members have a modulated transcriptional profile, which strongly suggests that EMS treatment encourages their activation Retrotransposon-based methods are efficient for fingerprinting and genetic polymorphism studies of sphaerococcum mutant forms, and can illuminate the genome dynamics affecting the genes responsible for the sphaerococcum phenotype.