| Brown planthopper (Nilaparvata lugens (St l)) is one of the primary pests of ricein many Asian countries, which highly influence the stable, high-yielding of the rice.The paper studied the rice defense responses induced by N.lugens ovipostion,analyzed the impact of oviposition fluid on rice defense responses, then separated andidentified small molecule compounds and proteins of the oviposition fluid. Finally westudied impact of salicylic acid rice defense signaling substances on the reproductiveof the N.lugens. Results are as follows:(1) Planthoppers oviposition spot and ovipositor characteristicsOviposition spots of N. lugens and Sogatella furcifera (Horváth) in the indicaTN1and japonica loose9changed from colorless to yellow, serious as brown. Theegg “cap” of N. lugens left outside the rice surface with visible oviposition fluid.However, eggs of S. furcifera in the rice sheath showed no visible oviposition fluidcovered its “cap”. The radians and length of N. lugens ovipositor were150.48±1.11deg and1191.87±21.97μm, which were quite different from those of S. furciferawith169.68±0.93deg in radians and1320.46±22.90μm in length.(2) N. lugens oviposition induced rice defense responses 3d after N. lugens oviposition, rice tissues produced responses such as localizedcell death, a wide range of hydrogen peroxide and callose deposition which weresimilar to the hypersensitivity phenomenon. After smeared oviposition fluid on thesurface of rice3d, then detected dead cells, hydrogen peroxide and callose, the resultsshowed no significant differences. After N. lugens oviposition3d, induced theexpression of defense genes of LOX, PAL, FPS, GDS, PR-1, PR-3, NR and POX, theexpression of FPS and POX were stronger than those in feeding, the expression ofLOX, GDS and NR were similar as those in feeding, and the expression of PAL, PR-1and PR-3were weaker than those in feeding.(3) N. lugens oviposition fluid component analysis17kinds of small molecules from oviposition fluid by GC-MS were isolated and14of them were identified, including3kinds of fatty acids accounted for87.8%and7kinds of fatty acid esters accounted for5.82%, besides there were other substancessuch as ketones and alkanes. Then six major oviposition fluid proteins were separatedby SDS-PAGE and analysis by MALDI-TOF-TOF, five of them matched with the N.lugens EST library. Oviduct calyx is the storage and synthetic organs of ovipositionfluid protein, and the main oviposition fluid protein expressed2days after emergence.Oviposition fluid protein gene were cloned and obtained four full-length sequences ofabout950bp.(4) Salicylic acid impact on the reproduction of N. lugensN.lugens were fed on artificial diet containing different concentrations ofsalicylic acid, low concentrations can promote ovarian development, increased adultbody weight, shorten the preoviposition stage and increase fecundity thus to affect thereproductive behavior of the N.lugens. High concentrations suppressed ovariandevelopment, and result in the formation of few eggs and the abnormal hypertrophy ofspermatheca. Rice spraying salicylic acid and BTH (2,1,3-Benzothiadiazole) andaccess N.lugens after3d of eclosion. The results showed that high concentrations ofsalicylic acid can increase its fecundity ability.Oviposition spot, eggs arrangement and egg coverings of N.lugens and S.furciferaoviposition are different. N.lugens oviposition can induce the rice defense response. The small molecule compounds and protein composition in N.lugens oviposition fluidmay be the elicitor that induced defense response of rice. The low concentrationsdefense signaling substances salicylic acid can promote ovarian development, shortenthe preoviposition and increase fecundity thus to affect the reproductive behavior ofthe brown planthopper. These results provide better understanding of mechanisms ofthe plant defense response to oviposition and theoretical basis of comprehensivemanagement strategies for N.lugens, which has both theoretical and practicalsignificance. |
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