RT-PCR analysis. Actin, LTR A, LTR B, integrase, reverse transcriptase (RT) and LINE primers were used. Genomic DNA with actin primers and BAC DNA with element specific primers were used as a positive control. Actin reveals a different sized PCR product when genomic DNA is used as a template than when cDNA is used as a template due to intron excision, and so can be used as an internal control for purity of RNA used for reverse transcription. Template DNA is indicated in the figure (size marker (M) 100 bp ladder), male genomic DNA (♂), female genomic DNA (♀), BAC DNA (30/L22 and 253/J6) S. latifolia male and female cDNA and RNA from leaves (L) and buds (B) and negative control (-, no template). PCR products were subjected to electrophoresis on 1% agarose gel and stained with ethidium bromide.