Xiudao Yu

BACKGROUND: The turnip aphid Lipaphis erysimi is a cruciferous crop pest with the potential to reduce yields by up to 90%. Treatment of L. erysimi infestations using insecticides has resulted in numerous cases of resistance in field populations yet genomic resources are lacking for this species, limiting the ability of researchers to investigate the molecular basis of resistance and develop management strategies. RESULTS: Here we describe the creation of a chromosome scale genome assembly for L. erysimi and the characterization of fenpropathrin resistance in this species using multi‐omics analysis. A 409 Mb genome was assembled for L. erysimi , with an N50 of 95.2 Mb and 90% of assembled content contained within four chromosome‐scale scaffolds. We identified a key M903L mutation in a voltage‐gated sodium channel gene that is targeted by fenpropathrin and the accompanying up‐regulation of cytochrome P450 and UDP‐glycosyltransferase detoxification genes. Using transgenic flies, we further confirmed the ability of L. erysimi CYP4CJ1 to confer fenpropathrin resistance in vivo . CONCLUSION: Mechanisms for fenpropathrin resistance in L. erysimi were identified through multi‐omics analysis and functional characterization. Collectively, this study provides valuable genomic resources for molecular investigations of L. erysimi and establishes a foundation for developing novel strategies to enhance pyrethroid efficacy in this species. © 2026 Society of Chemical Industry.

Olfactory perception is essential for mating, host location, and oviposition in insects. Odorant degrading enzymes (ODEs), such as antennal UDP‐glycosyltransferases (UGTs), clear redundant odorant molecules to recover olfactory capabilities. In this study, four antenna‐abundant DcUGT genes (i.e., DcUGT2B14 , DcUGT378A1 , DcUGT381A1 , and DcUGT381A2 ) were identified in Asian citrus psyllid Diaphorina citri , the main vector of citrus Huanglongbing pathogens. These genes were classified into three separate subclades, where DcUGT381A1 and DcUGT381A2 clustered together. qRT‐PCR analyses showed that these DcUGTs exhibited antenna‐biased expression profiles in both sexes and were constantly expressed from the first instar nymph to the adult stages. Moreover, they exhibited diverse responses to host plant odorants; specifically, exposure to linalool and myrcene upregulated the expressions of DcUGT2B14 and DcUGT381A2 , while citral and myrcene exposure increased the expression levels of DcUGT381A1 , suggesting their important roles in odorant processing. Molecular docking analysis predicted the key residues of DcUGTs in degrading odorants, indicating that hydrophobic interactions facilitate the binding affinity of DcUGT2B14, DcUGT381A2 , and DcUGT381A1 with myrcene. These results provide the comprehensive expression analysis of antennal UGT genes in D. citri , highlighting their possible role in odorant degradation and potential as targets for pest management.

The lack of sequence similarity among insect effectors necessitates the independent identification of effectors in the Asian citrus psyllid Diaphorina citri, the primary vector of huanglongbing pathogens. In this study, nine candidate effectors were identified from the D. citri salivary gland transcriptome. Among them, DcE13 exhibited the highest FPKM value and was delivered into plants during feeding. Transient expression in tobacco leaves showed that DcE13 is localized in the plasma membrane and around the nuclear envelope of plant cells. It inhibits BAX- and INF1-induced hypersensitive responses, suppresses callose deposition, and downregulates jasmonic acid marker genes NtPDF1.2 and NtFAD7. Furthermore, DcE13 knockdown decreased survival rates and fecundity of D. citri, as well as interrupted their phloem feeding, indicating its role as an effector that facilitates psyllid feeding. These results enrich our current understanding of D. citri feeding behavior while simultaneously offering a potential target gene for controlling this pest.

BACKGROUND: Piercing‐sucking insects secrete diverse repertoires of effectors into their hosts to weaken host defenses and promote infestation. The Asian citrus psyllid, Diaphorina citri Kuwayama, is the most destructive insect pest in citrus orchards because of its role as a vector for the huanglongbing pathogen, Candidatus Liberibacter asiaticus (CLas). However, specific effector proteins and their functions in D. citri remain unclear.RESULTS: We demonstrate that DcE1, a salivary protein gene from D. citri, is predominantly expressed in the salivary gland tissues and is delivered into host plants during feeding. Transient expression in tobacco leaves revealed that DcE1 was subcellularly localized in the cytoplasm and plasma membrane, where it inhibited BAX‐ and INF1‐induced cell death, suppressed callose deposition, and activated the salicylic acid pathway by upregulating the expression of endo‐β‐1,3‐glucanase NtBGL2 and regulatory protein NtNPR1. Further, DcE1 knockdown by double‐stranded RNA (dsRNA) injection decreased the survival rates of D. citri and interrupted D. citri phloem‐feeding on host plants.CONCLUSION: These results indicate that DcE1 is a novel effector that promotes plant susceptibility and enables D. citri feeding. These findings enhance our understanding of D. citri–plant interactions and offer a potential new target gene for the development of citrus protection strategies. © 2024 Society of Chemical Industry.

Aphids heavily rely on their olfactory system for foraging behavior. Odorant-degrading enzymes (ODEs) are essential in preserving the olfactory acuity of aphids by removing redundant odorants in the antennae. Certain enzymes within this group stand out as being enriched and/or biased expressed in the antennae, such as carboxylesterases (CXEs), cytochrome P450 (CYPs), glutathione S-transferases (GSTs), and UDP-glycosyltransferases (UGTs). Here, we performed a comparative transcriptome analysis of antennae and body tissue to isolate the antennal ODE genes of turnip aphid Lipaphis erysimi. A dataset of one CXE, seven CYPs, two GSTs, and five UGTs enriched in the antennae was identified and subjected to sequence analysis. Furthermore, qRT-PCR analyses showed that 13 ODE genes (LeCXE6, LeCYP4c1, LeCYP6a2, LeCYP6a13, LeCYP6a14.2, LeCYP6k1, LeCYP18a1, LeGST1, LeUGT1-7, LeUGT2B7, LeUGT2B13, LeUGT2C1.1, and LeUGT2C1.2) were specifically or significantly elevated in antennal tissues. Among these antennae-enriched ODEs, LeCYP4c1, LeCYP6a2, LeCYP6a13, LeCYP6a14.2, LeCYP18a1, LeUGT2B7, and LeUGT2B13 were found to exhibit significantly higher expression levels in alate aphids compared to apterous and nymph aphids, suggesting their putative role in detecting new host plant location. The results presented in this study highlight the identification and expression of ODE genes in L. erysimi, paving the path to investigate their functional role in odorant degradation during the olfactory processes.

The turnip aphid,Lipaphis erysimiKaltenbach, inflicts heavy damage on cruciferous crops worldwide. In these insects, olfactory perception is crucial for mating, host location, and oviposition. Both odorant‐binding proteins (OBPs) and chemosensory proteins (CSPs) are responsible for the delivery of host odorants and pheromones during initial molecular interactions. In this study, antennal and body transcriptomes ofL. erysimiwere generated through the deep sequencing of RNA libraries. A dataset of 11LeryOBPand fourLeryCSPtranscripts was identified among assembled unigenes and subjected to sequence analysis. Phylogenetic analysis found a one‐to‐one orthologous relationship between LeryOBP/LeryCSP and its corresponding homologs from other aphid species. Further quantitative real‐time PCR analyses across developmental stages and tissues showed that fiveLeryOBPgenes (i.e.,LeryGOBP,LeryOBP6,LeryOBP7,LeryOBP9, andLeryOBP13) andLeryCSP10were specifically or significantly elevated in the antennae compared with other tissues. Moreover, two transcripts (i.e.,LeryGOBPandLeryOBP6) exhibited remarkably higher expression levels in alate aphids, implying their potentially functional role in the perception of new host plant locations. These results present the identification and expression of OBP/CSP genes inL. erysimi, providing valuable insights into their putative role in olfactory signal transduction.

The relationship of DNA methylation and sex-biased gene expression is of high interest, it allows research into mechanisms of sexual dimorphism and the development of potential novel strategies for insect pest control. The Asian citrus psyllid, Diaphorina citri Kuwayama, is a major vector for the causative agents of Huanglongbing (HLB), which presents an unparalleled challenge to citrus production worldwide. Here, we identify the X chromosome of D. citri and investigate differences in the transcription and DNA methylation landscapes between adult virgin males and females. We find a large number of male-biased genes on the autosomes and a depletion of such on the X chromosome. We have also characterized the methylome of D. citri, finding low genome-wide levels, which is unusual for an hemipteran species, as well as evidence for both promoter and TE methylation. Overall, DNA methylation profiles are similar between the sexes but with a small number of differentially methylated genes found to be involved in sex differentiation. There also appears to be no direct relationship between differential DNA methylation and differential gene expression. Our findings lay the groundwork for the development of novel epigenetic-based pest control methods, and given the similarity of the D. citri methylome to some other insect species, these methods could be applicable across agricultural insect pests.