Detection of Ty1-copia-like reverse transcriptase sequences in Ipomoea batatas (L.) Poir.

Abstract Ty1-copia

-like sequences were PCR amplified from sweetpotato [Ipomoea batatas (L.) Poir.] L87-95 genomic DNA samples by using Ty1-copia reverse transcriptase-specific primers. PCR fragments within the expected size range were isolated, cloned, and sequenced. Inferred amino acid sequences of two randomly selected cloned fragments were found to be highly homologous to Ty1-copia-like reverse transcriptase sequences in the GenBank database. Subsequent sequencing of an additional 22 cloned fragments revealed a high level of reverse transcriptase sequence diversity (sequence divergence ranged from 2% to 73%). Southern blot hybridization analysis indicated that these sequences are present in the genome of I. batatas and taxonomic relatives in high copy numbers. PCR amplification from leaf cDNA obtained from a sweetpotato clone using Ty1-copia reverse transcriptase-specific primers yielded a Ty1-copia-like fragment. This is the first known report of the presence of genomic, and putatively expressed, Ty1-copia-like reverse transcriptase sequences in I. batatas.