2.8.1. GO Enrich

The up- or downregulated unigenes were enriched and assessed in the three Gene Ontology (GO) categories of biological process, cellular component and molecular function. The enrichment of upregulated unigenes from the SF-Sel strain was found in the Sus-Lab strain. Additionally, the number of unigenes of upregulated unigenes of the binding class in the molecular function category was highest, at 16, and the P450 genes were associated iron ion binding; with up- and downregulated P450 gene were enriched in the binging class (Supplementary Figure S3).

#### 2.8.2. Enrichment of DEGs in the KEGG Database

A total of 84 differentially expressed unigenes were enriched according to the KEGG database, which were related to organismal systems, genetic information processing, and metabolism, etc. The enriched DEGs found in the KEGG database were mainly included in categories such as "microbial metabolism in diverse environments (with a *p*-value of 0.00337)", "cardiac muscle contraction (*p*-value of 0.00153), "oxidative phosphorylation (*p*-value of 0.00114), "metabolic pathways (*p*-value of 0.000322)", "ribosome (*p*-value of 0.0000753), and "phototransduction-fly *(p*-value of 7.27 <sup>×</sup> 10−8). Additionally, the greatest number of unigenes enriched in metabolic pathways was 44 (Figure 4).

**Figure 4.** Bubble diagram of pathway enrichment of unigene on the different groups (Top 20). The abscissa means KEGG terms, and the ordinate means rich factor of each term. Red color means the terms of significant enrichment, and the bubble size indicates the number of enriched genes

#### *2.9. Screening the Candidate Genes*

The results showed that among the 74,119 unigenes, there were 198 unigenes involved in the detoxification and metabolism of foreign substances, and 138 were labeled cytochrome P450s, enriching the detoxification and metabolism genes of the white-backed planthopper. Compared with the Sus-Lab strain, the SF-Sel strain exhibited 7 significantly upregulated unigenes annotated as P450 genes, and a total of 4 gene types were found by NCBI alignment. One of the significantly upregulated unigenes was annotated as anorganic cation transporter, and 4 of the significantly upregulated unigenes were annotated as transcription factors (Table 2).


**Table 2.** Candidate P450 gene statistics.

#### *2.10. P450 Diversity Analysis*

Ten motifs (motif 1~motif 10) composed of very conservative amino acid residues were found in 54 of P450 genes (22 from our transcriptome data and other 32 downloaded from NCBI) of white-backed planthopper by meme search (http://meme-suite.org/tools/meme), on the contrary 24 motifs annotated with different functions were achieved by motif search (https://www.genome. jp/tools/motif/) (e.g., P450). Not only highly homologous sequences but also functional domains such as FAD\_binding\_1, Flavodoxin\_1 and NAD\_binding\_1 domains were found in AHM93009.1 (the Sequences of NADPH-cytochrome P450 reductase in *S. furcifera* downloaded from NCBI) and *unigene0040669* (Figure 5). The results indicated that these sequences were similar in function, and GO annotation showed that both were classified as NADPH-reductases. The other genes all exhibited P450 functional domains and the conserved structural domains of motif1 and motif3. Motif3 presented absolutely conserved EXXR residues, and their general topography and structural folding were highly conserved. The heme-binding loop (with an absolutely conserved cysteine that serves as the 5th ligand for the conserved heme iron core) was composed of a coil known as the 'meander', a four-helix bundle, helices J and K, and two sets of beta-sheets. Additionally, the conserved structural domains of motif7, motif4, motif8, motif6, motif5, motif3, motif1, and motif2 were found in *CYP6FD1* and *CYP4FD2*, but the conserved structural domains of motif9 and AAA (ATPases superfamily, consisted of ATP binding site, Walker A and B) were only found in *CYP4FD2* and *CYP6FD1*, respectively (Supplementary Figure S4).
