A meta-analysis of the expression of HaCREl, a young Copia LTR-retrotransposon of sunflower (Helianthus annuus L.)

The expression level of HaCREl, a sunflower long-terminal-repeats retrotransposon which was shown to be inserted into the genome in relatively recent times was studied in detail in order to evaluate its mutagenic potential. A meta-analysis was performed, using cDNA libraries available from public repositories including cDNA sequences isolated from roots of sunflower plants treated with different plant hormones, NaCl and polyethylene glycol. HaCREl was expressed at low level under all treatments and even in the control roots, compared to sunflower gene sequences. Only abscisic acid treatment induced over-expression of the retrotransposon. The putative cis-regulatory sequences responsible for HaCREl transcription were identified in its 5'-long-terminal-repeat. It was concluded that, even at low level, this still "young" retrotransposon maintains its capacity to transpose and hence its mutagenic potential.