| The locust is the main agricultural pest in China,and the outbreak of the locust has caused huge losses to the country and society.The mandible is the main tool for the feeding and damage,and its surface is covered with a hard and wear-resistant cuticle.Therefore,if the formation mechanism of mandible cuticle is explained,the key genes can be silenced by RNA interference to decrease the hardness of mandible to control the locust.In our previous work,the transcriptomic and proteomic data of the mandible of Locusta migratoria.In this thesis,the physiological functions of the high-abundance cuticular protein(CP)gene were studied to identify their effects on the hardness of the mandible.It provided a new idea and candidate target gene for the design of RNA pesticides against the locust.The specific research contents of this thesis are as follows:(1)Through the transcriptome and proteomic analysis,four CP genes with high abundance was selected.By alignment with the sequence in the locust genomic database,the target gene sequences were confirmed and the gene fragments were successfully cloned from the self-constructed cDNA library.The four genes are: 35501 and 30044(CPR-RR2 family);39539 and 30387(cuticular protein hypothetical).(2)Transcriptional profiles of the selected CP genes were analyzed.In terms of developmental specificity,35501 and 30044 were highly expressed before molting.The transcription level of 35501 was significantly higher than 30044.39539 was highly expressed before and after molting.30387 was highly expressed after molting.In terms of tissue specificity,35501,39539 and 30044 were highly expressed in the cuticle.30387 was highly expressed in the fore-gut,malpighian tubule and trachitis.(3)RNAi experiment was performed on day 1 fifth-instar nymph to verify the physiological functions of the selected CP genes.After RNAi experiment,the transcription level of target gene was significantly down-regulated.Genes 35501,39539,30044 and 30387 were silenced by 88.7%,74.3%,85.0% and 71.7%,respectively.After 35501 was silenced,the abnormal rate of locust reached 93.3%.33.3% of the nymphs died at the beginning of molting with the not fully opened molting line.16.7% of the adults were severely deformed.43.3% of the adults had abnormal wings and legs.The mandibles were deformed and gloomy and the hardness of the mandible decreased by 37.4%.After 39539 was silenced,the abnormal rate of locust reached 90%.13.3% of the nymphs died in the process of molting.76.7% of the adults had abnormal wings and legs.The mandibles were irregular and gloomy and the hardness of the mandible decreased by 45.0%.After 30044 was silenced,the abnormal rate of locust reached 83.3%.The adults had abnormal wings.The mandibles were gloomy.The hardness of the mandible has no significant changes.After 30387 was silenced,the abnormal rate of locust reached 80%.These adults had abnormal wings and legs.The mandibles were gloomy.The hardness of the mandible has no significant changes. |
