Comparison Of The Effectiveness Of Induced Rice Resistance To Herbivores Among Varieties And Cloning And Expression Analysis Of A Rice Defense-related Gene Encoding Germin-like Protein (GLP)

Based on previous research works, the influence of rice variety on the effectiveness of induced rice resistance to herbivores and the cloning and expression analysis of a rice defense-related gene encoding germin-like protein (GLP) were studied in a model system consisting of rice, the rice brown planthopper Nilaparvata lugens (Stal) and its egg parasitoid Anagrus nilapartvatae Pang et Wang. The results as follows:1) Using five rice varieties, TN1, IR26, IR64, Bing 97-59 and Xiushui 63, among which there are obvious differences in volatiles emitted from jasmonic acid (JA)-treated plants, as research materials, the preference of the parasitoid to volatiles of JA-treated plants of varieties were measured in a Y-tube olfactometer. Moreover, the influence of volatiles of these varieties on parasitism of N. lugens eggs in the field was also determined. On the basis of differences in volatiles released from JA-treated plants, five varieties could be roughly divided into three groups: group 1- TN1, group 2- IR26 and IR64, and group 3- Bing 97-59 and Xiushui 63. In a Y-tube olfactometer, female wasps preferred odors from TNI (group 1) and Bing 97-59 (group 3) to those from IR26 (group 2), whereas they showed no preference when given a choice between IR26 and IR64, and between Bing 97-59 and Xiushui 63. These preferences corresponded with observed parasitism rates in a field experiment. Parasitism of N. lugens eggs by A. nilaparvatae on plants that were surrounded by JA-treated plants of TN1 was the highest, followed by Bing 97-59 and Xiushui 63, and the lowest was on plants that were surrounded by IR26 and IR64. The lack of significant differences in parasitism among varieties in a second field experiment may have been due to a highpopulation density of the parasitoid, perhaps causing a strong interference among parasitoids. Comparing the volatiles with results from the behavioral assays and field experiments indicates that the quality (composition) of the volatile blends is more important for attraction than the total amount emitted by the plants. The results imply that the foraging success of natural enemies of pests can be enhanced by breeding for crop varieties that release specific volatiles.2) One gene encoding a germin-like protein 2 was cloned. Northern blot showed that the transcription levels of the GLP-2 in non-manipulated plants were low, but they were locally up-regulated after infestation by N. lugens and C. suppressalis. Within 12h after infestation, the expression levels of the gene were obviously up-regulated at 3h after infestation by both of the herbivores and the levels reached the maximum at 12h. Infestation by the herbivores did not increase the expression levels of the gene in non-infested tissues, i.e. the leaves of infested plants.