Ten fatty acyl‐CoA reductase family genes were essential for the survival of the destructive rice pest, Nilaparvata lugens

Abstract

BACKGROUND: Fatty alcohols are the precursors of sex pheromone components, wax esters and hydrocarbons in insects. Fatty acyl-CoA reductases (FARs) are important enzymes required for the reduction of fatty alcohol and thereby contribute to the production of cuticular hydrocarbon (CHC).RESULTS: Based on bioinformatics analyses we identified 17 FAR genes in the brown planthopper, Nilaparvata lugens. RNA interference against these genes demonstrated that ten NlFAR genes were essential for the survival of N. lugens. For instance, knockdown of NlFAR5, 6, 11 or 15 was lethal and caused a slender body shape, while the old cuticles of the respective animals remained attached to the abdomen or failed to split open from the nota. Knockdown of NlFAR9 resulted in a phenotype, with a smooth body surface and a decrease in CHC amounts. Similarly, CHC deficiency in N. lugens resulted in increased adhesion of water droplets and secreted honeydew to the insect surface and the inability of N. lugens to survive in paddy fields with varying humidity. Knockdown of NlFAR1,4,5,6,8,9,11 and 13 additionally resulted in female adult infertility.CONCLUSION: The present study illustrates the structural and functional differences of FAR family genes and provides potential targets for RNA interference-based rice planthopper management.

Advances in deciphering the genetic basis of insect cuticular hydrocarbon biosynthesis and variation

“…This illustrates a much farther-reaching and diverse functionality of insect FARs than previously appreciated. Perhaps most interestingly, knockdown of NlFAR7 also slightly increased gene expression of ACC, whereas NlFAR9 knockdown slightly increased the expression of a FAS gene in N. lugens (Li et al 2020). This revealed previously undiscovered correlations of the expression patterns of CHC biosynthesis genes and warrants further investigation of the underlying gene expression networks.…”

“…Interestingly, however, a homolog to wat in the brown planthopper Nilaparvata lugens, NlFAR7, is responsible for water-repellent properties of the cuticle and its knockdown resulted in a reduction of overall CHC quantities by almost half (Li et al 2019b, see Table 1). Knockdown of another FAR gene identified in N. lugens, NlFAR9, also reduced CHC levels in adult planthoppers, albeit apparently only affecting longer-chain n-alkanes (above C 26), providing further evidence that chain-lengthspecificity potentially constitutes a common trait in FARs (Li et al 2020).…”

“…Of the further 15 FARs identified in N. lugens, ten were found to be essential for cuticle shedding and wing expansion during molting with a lethal knockdown phenotype, while others had a marked detrimental effect on female fertility (Li et al 2020). This illustrates a much farther-reaching and diverse functionality of insect FARs than previously appreciated.…”

Apolipophorin-II/I Contributes to Cuticular Hydrocarbon Transport and Cuticle Barrier Construction in Locusta migratoria

“…The fatty acid synthesis initiating enzymes acetyl-CoA Carboxylase (ACC) and fatty acid synthase 3 (FASN3) and the lipophorin receptors LpR1 and LpR2 in D. melanogaster , for instance, have been reported to be essential for CHC production or trafficking and against water-loss ( Wicker-Thomas et al, 2015 ). In addition, in the brown plant hopper Nilaparvata lugens , some fatty acid elongases (ELOs) and reductases (FARs) have been shown to be crucial for correct CHC amounts and desiccation resistance in this rice pest ( Li et al, 2019 , 2020 ). Taken together, these proteins needed for CHC production or trafficking are crucial for water-loss and insecticide-penetration, thereby modulate the ecological adaptability of insects.…”

Cuticular Hydrocarbon Plasticity in Three Rice Planthopper Species

“…In addition to this, RNAi knockdown of BgFas1 causes a dramatic reduction of methyl-branched CHCs and a slight decrease of straight-chain CHCs [ 29 ]. Our previous studies demonstrated that knockdown of four ELO and two FAR genes resulted in a decrease of CHC amounts in Nilaparvata lugens [ 30 , 31 ]. Furthermore, reduction or elimination concerning the activity of the CYP4G encoded by CYP4G76 and CYP4G115 in N. lugens , DmCYP4G1 in D. melanogaster , LmCYP4G102 in Locusta migratoria , CYP4G19 in Blattella germanica and CYP4G51 in Acyrthosiphon pisum is responsible for the last step of CHC biosynthesis, and provokes a decrease in CHC amounts [ 32 , 33 , 34 , 35 , 36 ].…”