Chitinase-activity-independent anti-insect effect of class V chitinase from fig trees (Ficus carica).

Main conclusion: The feeding assay revealed growth-retardation effects of class V chitinase of Ficus carica on Spodoptera litura larvae and these effects were retained in its chitinase-inactive mutants. This study investigated the anti-insect activity of the class V chitinase (FcChiC) from latex of the fig tree (Ficus carica, Moraceae). The feeding of radish cotyledons, transiently producing FcChiC, to larvae of Spodoptera litura (Lepidoptera), resulted in significant growth reduction. A close homolog from Cannabis sativa (Cannabaceae) also demonstrated similar effects, while six other class V chitinases from plants, including Arabidopsis thaliana ChiC, did not. Notably, the anti-insect activity of FcChiC persisted in its chitinase-inactive mutants, which maintained chitin-binding ability. These results suggested that FcChiC and its C. sativa homolog are promising candidates for further research in pest control strategies.