Functional Analysis Of Ferritin Genes In The Brown Planthopper,Nilaparvata Lugens

The brown planthopper（BPH）,Nilaparvata lugens Stal,is a very destructive rice pest.Ferritin is widely distributed in eukaryotes,and plays a critical role in growth and development.To provide new inspiration for BPH control,three BPH ferritin genes were functionally characterized in this study.Three ferritin genes,ferritin 1 Heavy Chain（NlFer1）,ferritin 2 Light Chain（NlFer2）and soma ferritin（Nlsoma-Fer）,were identified from BPH.The effects of the three genes on growth and development and reproduction of BPH were studied by RNA interference（RNAi）experiments and the main results of this study are as followed:（1）temporospatial expression patterns showed that all three genes were expressed throughout the whole lifespan of BPH and were highly expressed in the gut;（2）in injection-mediated RNAi experiments,silencing Nlsoma-Fer resulted in only<14%mortality in BPH with no obvious phenotypes,and knockdown of NlFer1 or NlFer2 led to 100%mortality in 2^ndand 3^rdyoung nymphs and>60%mortality in 4^thand 5^thnymphs,which all showed retarded growth along with melanism and ecdysis death;（3）downregulation of NlFer1 or NlFer2 in newly emerged female adults caused undeveloped oocytes,resulting in remarkably reduced fecundity and zero hatching rate;（4）in RNAi concentration gradient experiments,BPH showed high sensitivity to both dsNlFer1 and dsNlFer2,that injection of only 0.625 ng dsRNA per3^rdBPH nymph resulted in>90%mortality;（5）the feasibility of feeding dsNlFer1and dsNlFer2 to BPH nymphs was proven.NlFer1 and NlFer2 are essential for the development and reproduction of BPH.Given that BPH is highly sensitive to their depletion,the two gut-highly-expressed genes are promising candidates for application in transgenic rice to control this sap-sucking insect pest.