Abstract
We screened the chemical library of azole-containing compounds for new strigolactone (SL) biosynthesis inhibitors by estimating the activity of these compounds to reduce the level of 2'-epi-5-deoxystrigol (epi-5DS) that is one of the identified SLs in rice. We found an imidazole-containing compound (1b) as a new compound inhibiting the epi-5DS production. Then we carried out a structure-activity relationship study of lb to discover more potent SL biosynthesis inhibitors and found 6b as the most potent inhibitor of the epi-5DS production among the synthesized compounds, which possesses an extended carbon chain and a triazole moiety instead of an imidazole moiety. Treatment of rice seedlings with 6b at 10 μM reduced SL levels in both roots and root exudates and did not exhibit the growth retardation caused by the inhibition of the gibberellin and/or brassinosteroid biosynthesis. In addition, root exudates of 6b-treated rice seedlings stimulated Striga germination less than those of control plants. These results suggest that 6b is an effective SL biosynthesis inhibitor and has a potential to be applied in the control of root parasitic weeds germination.
