| The greenbug (spp.), Schizaphis graminum (Rondani)(Homoptera: Aphididae) is a serious pest in wheat(Triticum aestivum(L.)), distributing in many regions of China and other regions of the world, causing hundred and thousand billion dollar lost in each year. It is a good idea to manage the greenbug in selecting and breeding resistant variety. Many researchers have studied the resources of variety, the mechanism of resistance, and the changes of greenbug population in different wheat varieties, and some aspects have also explored in genes of resistant wheat to greenbug, but little have been know in the mechanism of induced resistance in wheat after aphid feeding,the molecular mechanism of induced resistance,and the effects of induced resistance on aphid development and feeding behavior. In this paper, time series study of greenbug-elicited gene expressions in aphid-resistant and susceptible wheat varieties and comparison of aphids and elicitors-elicited specific molecular response were studied. The six specific genes of LOX, AOS, PDF1.2, PAL1, PR-1, and BGL2 were studied after different feeding time and elicitors treatment, and the effects of different elicitors-elicited on aphid development and feeding. Through the experiments, the mechanisms of induced resistance can be known after aphid feeding, resistant mechanism of plant, selection of resistant variety and providing the new method of integrated pest management through analyzing these results. Through analysising six specific genes, the time series study of greenbug elicited gene expressions in aphid-resistant and susceptible wheat varieties showed that the two genes that encode lipoxygenease(LOX) and allene oxide synthase (AOS) were induced and expressed in a long time. It demonstrated that mechanical wounding is a important response after aphid-feeding, but there are much difference in different variety and different time. PDF1.2 gene encodes the small antimicrobial protein defensin and lasts expression in ASTRON and only expresses highly in Qianjinzao in 48h. Transcripts encoding phe-ammonia lyase(PAL), a key enzyme in the iosynthesis of SA,flavanoid phytoalexins, lignin, and other cell wall phenolics doesn't be induced in two wheat varieties in anytime. Acidic pathogensis-related protein 1 (PR-1) and acidic, apoplastic form of ?-1,3-glucanase (BGL2) are good PR gene markers of SA-dependent induction. PR-1 is induced to express in ASTRON in 72h and 96h, but it doesn't be induced in Qianjinzao. BGL2 in response to aphid feeding is induced after 48h in ASTRON, but there is also not induced in Qianjinzao. The results that different elicitors and aphid feeding induced specific molecular response showed that the six specific genes were differentially induced after different elicitors and aphid feeding. Contrasting of control(CK), the mRNA of LOX, AOS, PDF1.2, PAL1, PR-1, and BGL2 were differentially induced to express after different treatments. The mRNA of PDF1.2 increased prominently after aphid feeding, but BTH treatment can't induce the gene expression of PDF1.2. The mRNA of BGL2 increased after aphid feeding and BTH treatment, but the gene of BGL2 didn't express after needle penetration. This showed that the defense response of aphid feeding is similar to mechanicalwounding and BTH treatment, but the response had a lot of difference. The response of aphid feeding induction is a specific response, there exists overlap with mechanical wounding and pathogen infection, but the defense response is different fronm mechanical wounding and pathogen infection. All differential genes expression analysis of time series study of greenbug elicited gene expressions in aphid-resistant and susceptible wheat varieties showed that about 700 segments from 200bp to 1200bp were differentially induced by 81 pairs primer in each cDNA sample. Ten differential expression segments were selected to clone and sequence. The results show seven genes were positive cloning through RT-PCR analysis. TA2E1,TA6E2 and TA6F3 were the same segments, they had high similarity with Oryza sativa (japonica cultivar-group) aos mRNA for allene oxide synthase(AB116527), TA2F2 was similar with Oryza sativa(japonica cultivar-group) mRNA for chitinose(D55713). The other three segments of TA8E3,TA2E4 and T1A1E5 had no similarity, they need analysis further. According the results, we know that jasmonic acid (JA)-dependent wounding response pathway, acidic, apoplastic form of ?-1,3-glucanase and acidic pathogensis-related protein 1 involved the defense response for aphid feeding. The resistance of induction on aphid development after aphid feeding and different elicitors showed the development time(days), adult weight(mg), mean relative growth rate(MRGR) were different after elicitores treatment in 1 and 3 days in 98-10-30 and BATIS(|t|>t0.05, P<0.05). The development time of greenbug in 98-10-30 was significantly different from SA and BTH treatment after one day(|t|>t0.05, P<0.05), it showed that SA and BTH can activate resistance of 98-10-30 to influence greenbug development time in one day; The aphid feeding, SA treatment, needle penetration, and BTH treatment had significant effects on development time, adult weight in 3 days in 98-10-30(|t|>t0.05, P<0.05). Different elicitores had some roles in 1day in BATIS for development of greenbug, but the role had nosignificant effect; BATIS was induced strongly to resist greenbug in 3 days for development time, adult weight(|t|>t0.05, P<0.05) and different elicitores had different roles on greenbug development. The results showed that the resistance of induction in different varieties had some difference after elicitores treatment, different induction times had different effects on inducing resistance, and different elicitores treatment had different roles on induction resistance. The feeding behavior of greenbug after aphid feeding and different elicitores demonstrated that time to first penetration(min), time of first probe(min), number of probes, number potential drop(pd), duration of all potential drop(min), time from first penetration to first E1(min), duration of all E1(min), duration of all E2(min), and duration of first E2>10 minate (min) had some differences in 98-10-30 and BATIS after aphid feeding , SA treatment, needle penetration, and BTH treatment after 3 days. The comparison of aphid feeding , SA treatment, and BTH treatment with control and the comparison of aphid feeding with needle penetration showed duration of all E2(min) had significant difference(|t|>t0.05, P<0.05); the duration of all E2(min) had also significant difference in BATIS after SA and BTH treatments. These results showed the resistance of induction had effects on phloem sap ingestion on greenbug feeding in 3 days after elicitores treatment in different varieties. All analysis showed that the resistance of induction had differences in molecular levels in different varieties, and the resistance of induction were also different in the temporal and spatial difference in molecilar levels after aphid feeding; aphid feeding induced specific resistance response which differs from elicitores treatments; there were some overlaps in different elicitores and aphid feeding and had some different effects on greenbug development and feeding behavior. The resistance mechanism of induction had some common characters to pests, but there had more specificity when we research the interaction between plant and insect, selecting the varieties and managing the pests.
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