In insects,the juvenile hormone(JH)and 20-hydroxyecdysone(20E)pathways jointly regulate fecundity,but only methyl farnesoate(MF)and ponasterone A exist in mites.Comparative transcriptomic analysis in Panonychus citri ...In insects,the juvenile hormone(JH)and 20-hydroxyecdysone(20E)pathways jointly regulate fecundity,but only methyl farnesoate(MF)and ponasterone A exist in mites.Comparative transcriptomic analysis in Panonychus citri showed that E75B was significantly downregulated when exposed to lufenuron.Knockdown of E75B significantly affects the expression of vitellogenin(Vg),Fushi tarazu factor 1(Ftz-f1)and juvenile hormone acid O-methyltransferase(JHAMT),reducing fecundity in mites.The knockdown of Ftz-f1 produced a more significant effect than the knockdown of E75B,indicating that the ponasterone A pathway positively regulates fecundity in P.citri.After the knockdown of JHAMT,the expression levels of both Vg and Ftz-f1 and fecundity were significantly increased,along with the inhibition of Kr-h1,suggesting that JHAMT was negatively correlated with fecundity in the regulatory network.Knockdown of Kr-h1 inhibited the expression of Vg and Ftz-f1 and fecundity,and whether the drop in fecundity is caused by Kr-h1 or Ftz-f1 is unclear.Subsequent feeding with MF induced Kr-h1 and Vg expression,whereas no significant effects were observed for JHAMT and Ftz-f1.Therefore,the MF pathway stimulates fecundity independently.RNA interference(RNAi)showed that JHAMT and Ftz-f1 inhibited each other,resulting in opposite effects of MF and ponasterone A pathways on steady-state fecundity when either factor changed.Meanwhile,JHAMT knockdown led to increased fecundity,indicating that the stimulating effect of the ponasterone A pathway was greater than the inhibiting effect of the MF pathway,and demonstrating the dominant role of the ponasterone A pathway.Therefore,the interaction between JHAMT and Ftz-f1 may be closely associated with the maintenance of MF-ponasterone A regulatory network homeostasis and is involved in the reduction of fecundity in P.citri induced by exposure to lufenuron.展开更多
Metamorphosis is one of the most important physiological processes in insects.It is regulated by a serial of ecdysone cascade genes.Recently,lots o f microRNAs(miRNAs)were investigated in insects;however,their functio...Metamorphosis is one of the most important physiological processes in insects.It is regulated by a serial of ecdysone cascade genes.Recently,lots o f microRNAs(miRNAs)were investigated in insects;however,their function in metamorphosis is largely unknown.In the present study,the dynamics of a small RNA population was investigated by RNA sequencing from the midgut of a lepidopteran pest Spodoptera litura during larval-pupal metamorphosis.A total of 101 miRNAs were identified,and 75 miRNAs were differentially expressed during the metamorphic process.The relationship between these differentially expressed miRNAs and 12 ecdysone cascade genes was analyzed by four classical software programs,and a multiple-to-multiple regulatory network was found to exist between these miRNAs and their targets.Among them,miR-14-3p and its two targets(EcR and E75)were chosen for further validation.MiR-14-3p had higher expression level in the 6 th instar larvae as compared with either the prepupae or pupae,which was opposite to that of both EcR and E75,two ecdysone cascade genes.Luciferase reporter assay confirmed that both EcR and E75 were regulated by miR-14-3p.Interestingly,the 3'untranslated regions are nearly identical to each other among different transcript variants of the ecdysone cascade genes,including EcR,USP,E75,E74,E78,E93,Hr3,Hr4,Hr39,K rhl and F tzfl.Thus,different transcript variants of one ecdysone cascade gene could be regulated by the same mi RNA.The above data suggest that the ecdysone signaling pathway is under the tight control of miRNA.These findings expand our understanding of the mechanism of insect metamorphosis and may also provide a novel possibility for the control of pest insects in the future.展开更多
基金supported financially by the Fundamental Research Funds for the Central Universities(SWU-XDPY22001)of China“Pioneer"and“Leading Goose"R&D Program of Zhejiang Province(2023C04014)the China Agriculture Research System of MOF and MARA.
文摘In insects,the juvenile hormone(JH)and 20-hydroxyecdysone(20E)pathways jointly regulate fecundity,but only methyl farnesoate(MF)and ponasterone A exist in mites.Comparative transcriptomic analysis in Panonychus citri showed that E75B was significantly downregulated when exposed to lufenuron.Knockdown of E75B significantly affects the expression of vitellogenin(Vg),Fushi tarazu factor 1(Ftz-f1)and juvenile hormone acid O-methyltransferase(JHAMT),reducing fecundity in mites.The knockdown of Ftz-f1 produced a more significant effect than the knockdown of E75B,indicating that the ponasterone A pathway positively regulates fecundity in P.citri.After the knockdown of JHAMT,the expression levels of both Vg and Ftz-f1 and fecundity were significantly increased,along with the inhibition of Kr-h1,suggesting that JHAMT was negatively correlated with fecundity in the regulatory network.Knockdown of Kr-h1 inhibited the expression of Vg and Ftz-f1 and fecundity,and whether the drop in fecundity is caused by Kr-h1 or Ftz-f1 is unclear.Subsequent feeding with MF induced Kr-h1 and Vg expression,whereas no significant effects were observed for JHAMT and Ftz-f1.Therefore,the MF pathway stimulates fecundity independently.RNA interference(RNAi)showed that JHAMT and Ftz-f1 inhibited each other,resulting in opposite effects of MF and ponasterone A pathways on steady-state fecundity when either factor changed.Meanwhile,JHAMT knockdown led to increased fecundity,indicating that the stimulating effect of the ponasterone A pathway was greater than the inhibiting effect of the MF pathway,and demonstrating the dominant role of the ponasterone A pathway.Therefore,the interaction between JHAMT and Ftz-f1 may be closely associated with the maintenance of MF-ponasterone A regulatory network homeostasis and is involved in the reduction of fecundity in P.citri induced by exposure to lufenuron.
基金grants from the National Natural Science Foundation of China(Grant No.31672357 and 31872285)。
文摘Metamorphosis is one of the most important physiological processes in insects.It is regulated by a serial of ecdysone cascade genes.Recently,lots o f microRNAs(miRNAs)were investigated in insects;however,their function in metamorphosis is largely unknown.In the present study,the dynamics of a small RNA population was investigated by RNA sequencing from the midgut of a lepidopteran pest Spodoptera litura during larval-pupal metamorphosis.A total of 101 miRNAs were identified,and 75 miRNAs were differentially expressed during the metamorphic process.The relationship between these differentially expressed miRNAs and 12 ecdysone cascade genes was analyzed by four classical software programs,and a multiple-to-multiple regulatory network was found to exist between these miRNAs and their targets.Among them,miR-14-3p and its two targets(EcR and E75)were chosen for further validation.MiR-14-3p had higher expression level in the 6 th instar larvae as compared with either the prepupae or pupae,which was opposite to that of both EcR and E75,two ecdysone cascade genes.Luciferase reporter assay confirmed that both EcR and E75 were regulated by miR-14-3p.Interestingly,the 3'untranslated regions are nearly identical to each other among different transcript variants of the ecdysone cascade genes,including EcR,USP,E75,E74,E78,E93,Hr3,Hr4,Hr39,K rhl and F tzfl.Thus,different transcript variants of one ecdysone cascade gene could be regulated by the same mi RNA.The above data suggest that the ecdysone signaling pathway is under the tight control of miRNA.These findings expand our understanding of the mechanism of insect metamorphosis and may also provide a novel possibility for the control of pest insects in the future.
