Phenotyping of Brassica napus L. plantlets affected during in vitro growth by the presence of epoxiconazole

Epoxiconazole like others triazole fungicides are known to be persistent in the soil. Several studies using foliar application experiments demonstrated the effect of its triazole metabolite as plant growth regulator through the anti-gibberellin activity. And notably, the reduction of Brassica napus L. growth can be attributed to the inhibition of gibberellin biosynthesis at the stage of conversion of ent-kaurene to ent-kaurenoic acid. We describe here an in vitro experiment studying the relationship between epoxiconazole in culture medium (0 mg L⁻¹, 0.120 mg L⁻¹ and 0.200 mg L⁻¹) and the phenotyping (root and shoot growth) of three varieties of winter rapeseeds (Brassica napus L. var. Catalina, var. ES Astrid and var. Toccata). Plantlets fungicide content was quantified using the QuEChERS extraction method following by an automated UHPLC-MS/MS analysis. Results showed that the shoots and roots growth of Brassica napus L. plantlets was significantly inhibited by epoxiconazole at 0.120 mg L⁻¹ independently of the variety. The concentration of 0.200 mg L⁻¹ leaded to necrosis and anthocyanosis symptoms and can be considered as lethal for in vitro growing explants. The huge epoxiconazole absorption by rapeseed plantlets clearly showed a dose-dependent relationship and was closely similar for the three varieties.