Rice blast disease and susceptibility to pests in a silicon uptake-deficient mutant lsi1 of rice

To elucidate the role of silicon more clearly in biotic stress such as pests and diseases, a silicon uptake-deficient mutant lsi1 originating from wild-type rice (cv. Oochikara) was used. When the mutant was grown in a seedling case, silicon did not accumulate in leaves (about 50–80 mg g−1 dry weight), regardless of the silicon amendment. In the paddy field, however, silicon increased three-fold (373 mg g−1 dry weight) in leaves with silicon amendment, compared with those (117 mg g−1 dry weight) with no silicon amendment. Lesion formation by Magnaporthe grisea was significantly suppressed in the leaves of the wild-type plant that had a high accumulation of silicon, but not in the leaves of the mutant that had a low silicon accumulation. Pest resistance was also observed in the leaves of the wild-type plant, but not in the mutant. These results demonstrated that silicon can protect rice plants from damage caused by biotic stresses.