Structural determination of elicitors in Sogatella furcifera (Horváth) that induce Japonica rice plant varieties (Oryza sativa L.) to produce an ovicidal substance against S. furcifera eggs.

Certain Japonica rice plant varieties (Oryza sativa L.) show resistance to the eggs of the white backed planthopper (Sogatella furcifera Horváth) by the formation of watery lesions and production of benzyl benzoate, an active ovicidal compound. Benzyl benzoate results in high ovicidal activity of S. furcifera eggs and reduces egg hatchability. The production of benzyl benzoate by the rice plants is only induced by an unknown elicitor(s) from the female S. furcifera. Therefore, we tried to isolate and identify these elicitors. An active 80% MeOH extract of S. furcifera was separated on a reverse-phase ODS MPLC, and the elicitor(s) was eluted in 100% MeOH and 100% EtOH fractions. Further separation of the active 100% MeOH fraction using a HPLC led to the isolation of four active compounds. The structures of each compound were determined by using NMR, LC-MS, and GC-MS spectra. The compounds were 1,2-dilinoleoyl-sn-glycero-3-phosphocholine, 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine, 1-palmitoyl-2-oleoyl-X-glycero-3-phosphoethanolamine, and 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine.

Elicitor(s) in Sogatella furcifera (Horváth) causing the Japanese rice plant (Oryza sativa L.) to induce the ovicidal substance, benzyl benzoate.

We elucidate the mechanism for inducing the production of ovicidal benzyl benzoate by Japonica rice varieties to kill eggs of the whitebacked planthopper, Sogatella furcifera (Horváth), lying in the rice plant. Even when subjected to physical damage by a needle or damage with water, the rice plant produced no benzyl benzoate. However, significant benzyl benzoate was produced when the plant was damaged with a methanol extract or homogenate of S. furcifera. The extract of the male did not induce the production of benzyl benzoate, but that of the female did. We concluded from these results that benzyl benzoate was induced by some elicitor(s) in the female of S. furcifera.