An Overview of Embryogenesis: External Morphology and Transcriptome Profiling in the Hemipteran Insect Nilaparvata lugens

Abstract

During embryogenesis of insects, the morphological and transcriptional changes are important signatures to obtain a better understanding of insect patterning and evolution. The brown planthopper Nilaparvata lugens is a serious insect pest of rice plants, but its embryogenesis has not uncovered. Here, we described embryonic development process of the pest and found it belongs to an intermediate-germ mode. The RNAseq data from different times (6, 30, 96, and 150 h, after egg laying) of embryogenesis were then analyzed, and a total of 10,895 genes were determined as differentially expressed genes (DEGs) based on pairwise comparisons. Afterward, 1,898 genes, differentially expressed in at least two comparisons of adjacent embryonic stages were divided into 10 clusters using K means cluster analysis (KMCA). Eight-gene modules were established using a weighted gene co-expression network analysis (WGCNA). Gene expression patterns in the different embryonic stages were identified by combining the functional enrichments of the stage-specific clusters and modules, which displayed the expression level and reprogramming of multiple developmental genes during embryogenesis. The "hub" genes at each embryonic stage with possible crucial roles were identified. Notably, we found a "center" set of genes that were related to overall membrane functions and might play important roles in the embryogenesis process. After parental RNAi of the MSTRG.3372, the hub gene, the embryo was observed as abnormal. Furthermore, some homologous genes in classic embryonic development processes and signaling pathways were also involved in embryogenesis of this insect. An improved comprehensive finding of embryogenesis within the N. lugens reveals better information on genetic and genomic studies of embryonic development and might be a potential target for RNAi-based control of this insect pest.

PCE3 Plays a Role in the Reproduction of Male Nilaparvata lugens

“…In addition, the hatching rate of eggs in the ds NlPCE3 treatment group was reduced. Among the 31 females that mated with ds NlPCE3 -treated males, 17 females laid eggs that could not hatch ( Figure 2 D), and no eye-spot (as described by Fan et al (2020) [ 21 ]) was found on these non-viable eggs ( Figure 3 ).…”

Dynamic transcriptome analysis of Bombyx mori embryonic development

“…WGCNA was used to analyze the association between the co‐expressed gene modules. It was also previously used for describing the embryonic development process in Nilaparvata lugens embryos and revealing key genes involved in overwintering in Anoplophora glabripennis larvae (Fan et al ., 2020; Xu et al ., 2021). A gene clustering tree was constructed based on the correlation between the expression levels of genes.…”

The KNRL nuclear receptor controls hydrolase‐mediated vitellin breakdown during embryogenesis in the brown planthopper, Nilaparvata lugens

“…(2020) described the complete process of embryonic development and analyzed embryonic samples at four different times (6, 30, 96 and 150 h after egg laying, AEL) using RNA‐Seq in N. lugens . To further explore the functions of these KNRL ‐regulated hydrolases in embryogenesis, we investigated their expression profiles in the different embryonic stages using public transcriptome data (PRJNA579876) (Fan et al ., 2020). Five selected trypsin genes were expressed at low levels in the early embryonic stages (6, 30 and 96 h AEL).…”

“…We speculate that KNRL plays an essential role in the embryo by coordinating the process of Vn breakdown and thus affecting the temporal expression of genes that encode proteolytic enzymes. Using public transcriptome data (Fan et al ., 2020), we compared the expression patterns of genes encoding proteolytic enzymes at different embryonic development stages. Two selected genes with predicted cathepsin activity were highly and stably expressed throughout embryogenesis, confirming their critical role in the breakdown of nutrient reserves throughout embryonic development.…”