Priming of rice seed with decoyinine enhances resistance against the brown planthopper Nilparvata lugens

The brown planthopper (BPH), Nilaparvata lugens, is a destructive pest of rice in Asia. The secondary metabolite, decoyinine (DCY), is produced by Streptomyces hygroscopicus. Previous studies on DCY have focused on its antimicrobial and antitumor properties. However, its effect on insect resistance of rice remains unclear. Here, we investigated whether pretreatment of rice seeds with DCY improves plant resistance against BPH. The results showed that rice plants grown from DCY-pretreated seed displayed higher resistance to BPH. Two sex life table analyses revealed that the fecundity, the intrinsic rate of natural increase (r(m)), the net reproductive rate (R-0), the finite capacity of increase (lambda) and population size of BPH fed on rice pretreated with DCY significantly decreased compared to the control. The ovary development and the expression level of vitellogenin (NlVg) were decreased in BPH fed on DCY-pretreated rice. Seed priming with DCY significantly increased the duration and number of occurrence of the np, N2, N3 waveforms and decreased the duration of N4-b waveforms of BPH. Additionally, seed priming with DCY also decreased the feeding and oviposition preference of rice to BPH. Therefore, we inferred that seed priming with DCY could enhance rice resistance to BPH.