| Trichogramma japonicum is an important egg parasite of Lepidoptera pests in rice fields.At present,it can be released in field submerged mode through indoor large-scale breeding,which has a good control effect on pests.Because the shelf life of Trichogramma japonicum conventionally bred is short,diapause treatment of Trichogramma in the production of Trichogramma japonicum has become one of the important means to prolong the shelf life Previous studies have shown that the diapause effect of Trichogramma japonicum can be effectively improved by short light treatment.However,different photoperiods will affect the biological characteristics of Trichogramma japonicum,and then affect the production of Trichogramma japonicum.Therefore,in this paper,Trichogramma japonicum was used as materials to explore the effects of different photocycles on its parasitic ability and eclosion law.At the same time,transcriptome data were used to reveal the circadian law of gene expression and screen internal reference genes.Fluorescence quantitative PCR was used to explore the expression patterns of clock,period,timeless and cryptochrome under different photocycles,It provides a theoretical basis for revealing the effect of photoperiod on Trichogramma japonicum.The main results are as follows(1)Effect of photoperiod on parasitism of Trichogramma japonicumUnder three photoperiodic conditions(L8:D16,L12:L12 and L16:D8),The results of parasitism behavior of Trichogramma japonicum showed that the parasitism of L8D16 was significantly higher than that of L1 2D 12 and L16D8 under short photoperiod(L8D16),There was no significant difference in the parasitism of photoperiod to Trichogramma japonicum.Under long light conditions(L16:D8),the female offspring of Trichogramma japonicum parasitized under L16D8 photoperiod account for a large proportion in the second generation,which was significantly higher than that under L8D16 and L12D12 photoperiods.But there was no significant difference in the 1st,3rd4th generation.Under short light L8D16 experimental conditions,In the second generation of parasitism,the emergence rate of Trichogramma japonicum bred under long light(L16D8)photoperiod was higher,which was significantly higher than that under L8D16 and L12D12 photoperiod.But there was no significant difference in the 1st,3rd4th generation.Under the medium light experimental conditions(L12D12),the emergence rate of the first generation of parasites under the Photoperiod of L1 2D 12 was significantly higher than that under the Photoperiod of L8D16 and L16D8.There was no significant difference in eclosion rate under different photoperiods when the photoperiod was L16D8.(2)Effect of photoperiod on emergence of Trichogramma japonicum,The results of eclosion behavior of Trichogramma japonicum under different photoperiods showed that under the L8D16 short light test,the eclosion peak of Trichogramma japonicum parasitized by 8am and 14pm were concentrated on the 9th days after parasitization;The emergence peak of 20pm parasitism was on the 10th day after parasitism.Under medium light L12D12,the emergence peak of the three parasitic times was the 10th day after parasitism.Under L16D8 long light,The emergence peak of 8am parasitism was on the 9th day after parasitism,and the emergence peaks of 14pm and 20pm parasitism were concentrated on the 10th day after parasitism.The eclosion time points under the three photocycles were relatively concentrated,reaching the peak at 6am-8am,and then began to decline.(3)Transcriptome sequencing and screening of internal reference genesUsing Illumina novaseq TM The transcriptome of 18 samples of parasitic eggs of Trichogramma japonicum at different sampling times was sequenced on the 6000 platform,and finally 119gb transcriptome data were obtained.The results of data assembly showed that 64359 transcripts and 30357 unigenes were obtained,and the length of N50 was 2311bp and 2124bp respectively.After the sample RNA was extracted,the library was constructed and sequenced.Referring to the transcriptome sequencing results,10 potential internal reference genes were selected in this study,ACTR2、ARPC2、EF1a、EEF1D、HSP70、GAPDH、TMEM209、PABPC1L、SFRS7 和 CSNK1a1,The efla gene expression was the most stable under temperature treatment Trichogramma japonicum,Sfrs7 gene expression was the most stable under different feeding conditions;The expression of pabpc1l gene was the most stable in pesticide treatment and different development periods.In this experiment,pabpc1l and efla were selected as internal reference genes.(4)Expression patterns of circadian clock genes under different photoperiodsThe relative expression of the four circadian clock genes has a circadian rhythm,Among them,the expression of per、cry was lower in light period and higher in dark period under long and short light conditions;The expression of clk、tim was higher in light period and lower in dark period.The expression of clk gene was up-regulated in the light period under the conditions of short light and medium light test(L8D16 and L12D12),reached the maximum at about 6h in the light period,and down regulated in the dark period.Under the conditions of long light(and L16D8),the expression of clk gene was up-regulated in the light period,reached the maximum at about 12h in the light period,showing a downward trend,but the expression was significantly higher than that in the dark period.tim gene expression was higher in light period and lower in dark period.Under three photoperiods,the gene expression reached the maximum at about 4H in the light period,and then decreased.Under medium and long light(L12D12 and L16D8),the gene expression of cry gene was up-regulated in dark period for about 6h,and down regulated in light period.Under short light(L8D16),the gene expression was up-regulated in dark period for about 8h,and reached the maximum.Under the condition of short light(L8D16),the gene expression of per gene is up-regulated in the dark period and reaches the maximum value about 12h after entering the dark period.Under the condition of medium light(L12D12),the gene expression is up-regulated in the dark period and down regulated in the light period,and reaches the maximum value about 8h after entering the dark period.Under the condition of long light(and L16D8),the gene expression reaches the maximum value about 6h after entering the dark period. |
PDF Full Text Request