The β‐N‐acetylhexosaminidase gene family in the brown planthopper, Nilaparvata lugens

Abstract

β-N-Acetylhexosaminidases (HEXs) are enzymes that can degrade the chitin oligosaccharides that are produced by the activity of chitinases on chitin in insects. Using bioinformatic methods based on genome and transcriptome databases, 11 β-N-acetylhexosaminidase genes (NlHexs) in Nilaparvata lugens were identified and characterized. Phylogenetic analysis revealed a six-grouped tree topology. The O-Linked N-acetylglucosaminidase (O-GlcNAcase) group includes NlHex11, which harbours a catalytic domain that differs from that of the other 10 NlHexs. Observations of the expression of NlHexs during different developmental stages revealed that NlHex4 is expressed with periodicity during moulting. Although the tissue-specific expression patterns of most NlHexs were nonspecific, NlHex4 was found to be expressed mainly in the female reproductive system as well as in the integument. RNA interference (RNAi) demonstrated failure to shed the old cuticle only in the nymphs treated with double-stranded RNA (dsRNA) targeting NlHex4, and these nymphs eventually died; no observable morphological abnormalities were found in insects treated with dsRNAs targeting the other 10 NlHexs. Based on this study and our previous analyses, a '5 + 1 + 3' pattern of chitinolytic enzymes is proposed, in which five chitinases, one NlHEX and three chitin deacetylases are required for moulting in N. lugens. A better understanding of chitin metabolism in the hemimetabolous insect, N. lugens, would be achieved by considering three chitinolytic enzyme families: chitinase, chitin deacetylase and β-N-acetylhexosaminidase.

Glycogen Phosphorylase and Glycogen Synthase: Gene Cloning and Expression Analysis Reveal Their Role in Trehalose Metabolism in the Brown Planthopper, Nilaparvata lugens Stål (Hemiptera: Delphacidae)

“…Investigation showed that, from 2000 to 2010–2011, rice pests caused a loss of up to 48 million ha in China (Zhao et al 2014). The hemimetabolous Brown planthopper Nilaparvata lugens Stål (Hemiptera: Delphacidae), which causes huge yield losses directly, is one of the most destructive insect pests, as they can only feed and breed on rice or wild rice (Xi et al 2014, 2015a,b). This pest damages rice plants by directly sucking the phloem sap and transmits plant viruses (Ghaffar et al 2011, Yang et al 2014).…”

“…Originally, insecticide control was an important and very convenient way to control and decrease pest populations, but its improper use has led to pest resurgence and resistance, and to the accumulation of chemical residues (Xi et al 2014). In N. lugens , gene-function studies have also shown that RNAi of target genes could be used a pest-control strategy (Wang et al 2012, 2015; Xi et al 2014, 2015a,b; Liu et al 2015; Zhao et al 2016; Yang et al 2017). …”

Application of Virus-Derived Small Interfering RNAs (vsiRNAs) in Rice Viruses with Insect Vectors, Especially <em>Rice Grassy Stunt Virus</em>

“…Enolase gene (Eno1) silencing revealed down-regulation of mRNA level significantly in N. lugens and also decreased the egg laying capacity and population size during next generation of the planthopper [100]. Silencing of N-acetylhexosaminidase gene causes the molting and death of brown planthopper [108] Here we have mentioned some roles of viral suppressors for Rice grassy stunt virus.…”

RNA Interference in Insect Vectors for Plant Viruses

“…In another study, silencing acyl-coenzyme A oxidase ( ACO ) [119,120] and glutamine synthetase ( GS ) [121] decreased the reproduction and population growth in BPH females, while knockdown of NIHsp90 by dsRNA injection reduced the survival and verified its role in thermotolerance [122]. Another study demonstrated the importance of β- N-acetylhexosaminidase gene family in BPH and the silencing of this gene caused molting failure and death [123]. Yang et al (2016) [124] demonstrated that knockdown of two trehalose-6-phosphate synthases ( TPS1 and TPS2 ) severely affected chitin metabolism and increased molting deformities and mortality rates, and showed that the nutritional signaling regulates Vitelogenin synthesis and egg development in N. lugens [125,126].…”