Preliminary Analysis Of Mechanism In Response To Thermal Stress In Tytthus Chinensis (Stal) (Heminoptera:Miridae)

Tytthus chinensis Stal(Hemiptera:Miridae)and Cyrtorhinus lividipennis Reuter(Heteroptera:Miridae)are the major predatory natural enemies of rice planthoppers,and therefore play an important role in the regulation of these herbivore preys'populations in the field.Ecological experiments suggested that these two predators has different tolerance to the high temperature stress,but little information is available on the molecular mechanism underlying.In addition,less is known in the genes involved in the gender-differentiation of T.chinensis,which might be important regulators for the reproduction rate and the population size of this predator in nature.In this study,we made a systematic comparison for the high temperature tolerance of the two predators.And obtained the transcriptome information of T.chinensis by using Illumina HiSeqTM 2500 sequencing.The crucial functional genes related to gender-difference and heat tolerance(the heat shock genes)were analyzed.The transcriptome information of T.chinensis offers a basis for the characterization of the adaptation of this insect in the molecular level in future.1.Comparison of heat tolerance,predation ability and water retention capacity under high temperature between T.chinensis and C.lividipennis.After the male and female adults of T.chinensis and C.lividipennis were exposed to 45 ?,the survival rates of these two species showed significant difference.The survival time of T.chinensis was 13 times higher than of C.livdipenni,indicating that T.chinensis is more tolerant to high temperature than C.lividipennis.There was no significant difference between male and female in these two bugs individually,although female adults' survival rate was slightly lower than male adults in both species.The predation capacity of the C.lividipennis was significantly decreased with the increase of temperature,while the T.chinensis's ability was not affected.However,the predation ability of T.chinensis did not change significantly after reaching a certain temperature(30?).Thus,the impact of high temperature stress on C.lividipennis is more pronounced.After the high temperature treatment,the water loss of the C.lividipennis was higher than that of the T.chinensis,but there was no significant difference.Therefore,the difference of the high temperature tolerance between the two species was not2.The transcriptome information of T.chinensisDe novo sequencing of T.chinensis male and female adults transcriptome was carried out using Illumina HiSeqTM 2500 sequencer.In total,30.13 Gb clean reads were obtained and each sample had a Clean Data of 4.20 Gb,which were assembled into 252,720 unigenes,and among them 30,592 unigenes were annotated,of which 25,604 unigenes were further matched to the known sequences in NCBI,among which 10,092 COG annotations were produced,11,789 were annotated as 55 GO secondary classification,and 14,709 unigenes were located in 258 KEGG pathways.10.81%of the unigenes showed high homology with Zootermopsis nevadensis and 17.3%of the unigenes showed low homology with the known sequences in NCBI,which constituted our unique transcripts.Of the 5,061 significant gender-differential expression genes,the number of up-regulated and down-regulated genes was 2,134 and 2,927 respectively.While most genes(22,381)did not show significant difference of expression between the male and female adults(P ? 0.01,Fold Change ? 2).For the differentially expressed genes,1,526 genes were involved in 175 metabolic pathways(KEGG database).Most differential genes were enriched in 20 metabolic pathways,including:Aminoacyl-tRNA,Basal transcription factors,Base excision repair,DNA replication,Fanconi anemia pathway,Glycosphingolipid biosynthesis-lacto and neolacto series,Glycosaminoglycan biosynthesis-heparan sulfate/heparin,Hippo signaling pathway-fly,Homologous recombination,Mismatch repair,mRNA surveillance pathway,Non-homologous end-joining,Nucleotide excision repair,Pyrimidine metabolism,Ribosome biogenesis in eukaryotes,RNA degradation,RNA polymerase,RNA transport,Spliceosome and Terpenoid backbone biosynthesis.3.Real-time quantitative PCR validation and phylogenetic analysis of HspsThe expression of shsp,hsp70,hsp60 and hsp90 mRNA in Hsps families of both male and female adults were significantly affected by high temperature.Compared with the control(26?),the expression of hsp70-2,hsp70-3,etc.in female adults were significantly different and hsp70-1,hsp90-1 were not.The expression of hsp70-1,hsp70-2,etc.in female adults were significantly different,and shsp-2 was not.The expression levels of shsp-1 and shsp-2 in the female adults were significantly higher than those in the males,and the expression of other Hsp genes in females was significantly lower than those in males.