Design, synthesis and anti-TMV activity of novel α-aminophosphonate derivatives containing a chalcone moiety that induce resistance against plant disease and target the TMV coat protein

Plant viral diseases, known as “plant cancer”, with high contagiosity can substantially reduce crop quality and yield. To identify potential anti- tobacco mosaic virus (TMV) agents with different mechanisms, a series of novel α-aminophosphonate derivatives containing a chalcone moiety were designed and synthesized. Bioassay results revealed that some target compounds exhibited improved curative activity against TMV in vivo, and the EC 50 value of compound B 3 was 356.7 mg L −1 . The activities of the defensive enzymes POD and CAT from tobacco leaves treated with B 3 and B 17 showed that these target compounds could improve the photosynthetic ability of the leaves and activate plant host resistance against TMV infection. The binding constant between B 3 and TMV Coat Protein (CP) (2.51 × 10 8  M −1 ), calculated by the fluorescence titration experiment and docking results, revealed that B 3 has a strong interaction with TMV CP. Further docking analysis revealed that B 3 was embedded between two layers of the TMV CP, which was consistent with the 2:1 binding mode of TMV CP and B 3 determined by the binding affinity experiment. The TEM morphological study of TMV treated with B 3 and B 17 indicated that this series of target compounds may trigger the disassembly of TMV by interacting directly with TMV CP. This study provides new insight for the discovery of antiviral compounds with two different mechanisms of action.