OARE-1, a Ty1-copia retrotransposon in oat activated by abiotic and biotic stresses

Transcriptionally active Ty1-copia LTR-retrotransposons were found in oat using RT-PCR for amplifying the reverse transcriptase domain. Sequence analysis of the RT-PCR clones suggested that oat LTR-retrotransposons consist of at least seven groups, which were tentatively designated as Oatrt1 to Oatrt7. A full length copy of Oatrt1 was isolated from an oat genomic library, and was designated OARE-1. OARE-1 was 8,665 bp long and a member of the BARE-1 subgroup. The oat genome carried it in multiple copies (at least 10,000 copies / a hexaploid genome). The expression of OARE-1 was intensively induced by wounding, UV light, jasmonic acid and salicylic acid, and its pattern was very similar to that of the PAL (phenylalanin ammonia lyase) gene. Furthermore, OARE-1 was highly activated by infection with an incompatible race of the crown rust fungus, Puccinia coronata. These results suggest that OARE-1 is highly sensitive to various abiotic and biotic stimuli leading to plant defense responses.