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We report the genome sequence of Aleuroclava gordoniae-associated polerovirus (AgAP), identified from the whitefly Aleuroclava gordoniae. The 5,650-nt AgAP genome contains 6 open reading frames. Phylogenetic analysis places AgAP within the genus Polerovirus, which comprises plant-infecting viruses. This study provides a genomic resource for further investigation of virus-insect associations.
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Piercing-sucking insects, such as whiteflies and aphids, cause massive economic losses in major crops around the world. During feeding, the stylets of piercing-sucking insects navigate cuticles, cell walls, epidermal cells, and mesophyll cells; thus, these barriers are vital for the resistance of plants to insects. However, the relationship between insect stylet probing behavior and the composition and structure of these barriers remains unclear. Here, we identified a tobacco Cuticle Related Factor (NtCRF), which was induced significantly by whitefly infestation. Bioassays showed that NtCRF positively regulated plant resistance against whiteflies and green peach aphids. Silencing of NtCRF did not affect plant jasmonic acid (JA) and salicylic acid (SA) defenses but shortened the stylet probing time of phloem-feeders. Further studies confirmed that silencing of NtCRF resulted in significant structure destruction of the leaf cuticle and led to increased epidermal permeability. Overexpression of NtCRF in Arabidopsis also significantly enhanced the plant's resistance against whiteflies and green peach aphids. Our findings expand understanding of plant-insect interactions and provide a strategy for genetic improvement of crop resistance against piercing-sucking insects.
This study presents the complete genome sequence of a novel nege-like virus identified in whiteflies (Bemisia tabaci MEAM1), provisionally designated as whitefly negevirus 1 (WfNgV1). The virus possesses a single-stranded RNA genome comprising 11,848 nucleotides, organized into four open reading frames (ORFs). These ORFs encode the putative RNA-dependent-RNA-polymerase (RdRp, ORF 1), a glycoprotein (ORF 2), a structural protein with homology to those in the SP24 family, (ORF 3), and a protein of unknown function (ORF 4). Phylogenetic analysis focusing on RdRp and SP24 amino acid sequences revealed a close relationship between WfNgV1 and Bemisia tabaci negevirus 1, a negevirus sequence recently discovered in whiteflies from Israel. Both viruses form a clade sharing a most recent common ancestor with the proposed nelorpivirus and centivirus taxa. The putative glycoprotein from ORF 2 and SP24 (ORF 3) of WfNgV1 exhibit the characteristic topologies previously reported for negevirus counterparts. This marks the first reported negevirus-like sequence from whiteflies in the Americas.
TAXONOMY: Cucurbit leaf crumple virus (CuLCrV); Begomovirus cucurbitae; Geminiviridae; Geplafuvirales. GEOGRAPHICAL DISTRIBUTION: The presence of CuLCrV is exclusively limited to North America, mainly Mexico and the United States. PHYSICAL PROPERTIES: CuLCrV is a bipartite begomovirus comprising two circular single-stranded DNA molecules (DNA-A and DNA-B), encapsidated within geminate icosahedral particles. GENOME AND ORGANIZATION: CuLCrV possesses a bipartite genome of DNA-A (2632 nucleotides) and DNA-B (2600 nucleotides). DNA-A contains five open reading frames (ORFs): AV1 (coat protein), AC1 (replication-associated protein), AC2 (transcriptional activator protein), AC3 (replication enhancer protein) and AC4. DNA-B contains two ORFs: BV1 (nuclear shuttle protein) and BC1 (movement protein). TRANSMISSION: CuLCrV is transmitted by the sweetpotato whitefly, Bemisia tabaci, in a persistent, circulative and non-propagative manner. HOSTS: CuLCrV primarily infects crop members of the Cucurbitaceae and snap bean (Phaseolus vulgaris, Fabaceae). Multiple weed species belonging to Brassicaceae, Convolvulaceae, Cucurbitaceae and Verbenaceae act as persistent virus reservoir hosts. SYMPTOMS: Symptom expression varies with host and infection timing. In cucurbits, infection induces leaf crumpling, thickening and downward curling of leaves, with green streaks and distortion of fruits. In snap bean, symptoms include leaf distortion, chlorosis and malformed pods. CONTROL: No commercial cultivars with resistance to CuLCrV are available for cucurbit crops, although some resistance has been reported in snap bean cultivars. Therefore, management relies primarily on integrated disease management.
Bemisia tabaci (Gennadius) whitefly (BtWf) is an invasive pest that has already spread worldwide and caused major crop losses. Numerous strategies have been implemented to control their infestation, including the use of insecticides. However, prolonged insecticide exposures have evolved BtWf to resist these chemicals. Such resistance mechanism is known to be regulated at the molecular level and systems biology omics approaches could shed some light on understanding this regulation wholistically. In this review, we discuss the use of various omics techniques (genomics, transcriptomics, proteomics, and metabolomics) to unravel the mechanism of insecticide resistance in BtWf. We summarize key genes, enzymes, and metabolic regulation that are associated with the resistance mechanism and review their impact on BtWf resistance. Evidently, key enzymes involved in the detoxification system such as cytochrome P450 (CYP), glutathione S-transferases (GST), carboxylesterases (COE), UDP-glucuronosyltransferases (UGT), and ATP binding cassette transporters (ABC) family played key roles in the resistance. These genes/proteins can then serve as the foundation for other targeted techniques, such as gene silencing techniques using RNA interference and CRISPR. In the future, such techniques will be useful to knock down detoxifying genes and crucial neutralizing enzymes involved in the resistance mechanism, which could lead to solutions for coping against BtWf infestation.
Species of the genus Orius, diminutive predatory insects that act as natural enemies of other arthropods, are frequently employed in agricultural pest management for controlling various pests, such as thrips, mites, aphids, whiteflies, etc. However, the scarcity of high-quality genomic resources for these predators hinders our comprehension of their population evolution and predation ecology. Consequently, we assembled and annotated a chromosomal-scale genome of Orius nagaii by collating PacBio and Illumina sequencing and Hi-C genomic analysis techniques. The final genome assembly size 152.62 Mb, with scaffold and contig N50 lengths of 11.53 and 2.39 Mb, respectively. It is organized into 12 pairs of autosomes and a pair of XY sex chromosomes. The quality assessment of the genomic data with BUSCO revealed a completeness of 98.5% (n = 1,367). Also, 11,917 protein-coding genes were discovered, with 94.28% of them having functional annotations. The high-quality genome of O. nagaii produced serves as a valuable resource for comprehending the interactions between predatory natural enemies and hosts, along with their evolutionary trajectories.