Predominant expression of a peroxidase gene in staminate flowers of Mercurialis annua

A direct correlation between the feminizing process of male plants of Mercurialis annua by benzylaminopurine and the disappearance of male‐specific peroxidases was established. In order to understand the process of hormonal regulation of the sexual differentiation and peroxidase activity, two peroxidase cDNA clones were selected from a male flower cDNA library with degenerated oligonucleotide probes encoding a peroxidase‐specific site. These clones contained three peroxidase‐specific sequences and an Eco RI restriction site. The two Eco RI fragments of one cDNA clone were subcloned and used as probes to analyse the expression of corresponding gene(s). The northern blot analysis showed hybridization on a single mRNA band with a predominant expression in male flowers. The feminizing treatment with a cytokinin induced the progressive disappearance of the hybridization signal in correlation with the disappearance of male specific isoperoxidases.