Quinclorac is widely used in rice cultivation; however, its persistent residue poses a serious risk to subsequent tobacco crops in rice-tobacco rotation systems, limiting the sustainability of this practice. Although rice and tobacco exhibit markedly different sensitivities to quinclorac, the molecular basis for this divergence remains unclear. In this study, we investigated the differential molecular mechanisms from stress perception to phenotypic response by integrating comparative transcriptomics, physiological profiling, and metabolic pathway analysis. Under quinclorac, the tobacco cultivar K326 (K326) suffered severe growth inhibition and oxidative damage, whereas the rice cultivar Nipponbare (NPB) maintained internal homeostasis. Comparative transcriptomics analysis revealed putative distinct response strategies. K326 may activate a defense response program characterized by strong induction of mitogen-activated protein kinase (MAPK) and ethylene/jasmonic acid signaling pathways, followed by large-scale transcriptional reprogramming dominated by MYB and WRKY transcription factors. In contrast, NPB may adopt a steady-state prioritization strategy, upregulating NAC transcription factors to enhance glutathione-based detoxification while sustaining the core metabolic processes, including photosynthesis. Collectively, our work provides a systematic framework for understanding the molecular basis of the differential quinclorac response in rice and tobacco.

Fusarium wilt, caused by Fusarium oxysporum f. sp. cucumerinum (FOC), poses a major threat to economically important crops worldwide. Figleaf gourd (Cucurbita ficifolia) has been widely adopted as a rootstock for FOC-susceptible cucumber (Cucumis sativus) due to its strong resistance, although the underlying molecular mechanisms remain elusive. In this study, we leveraged the contrasting FOC resistance between C. ficifolia and C. sativus to perform a comparative analysis aimed at elucidating the molecular basis of Fusarium wilt resistance in C. ficifolia. Compared to C. sativus, resistant C. ficifolia exhibited milder wilting, enhanced antioxidant enzyme activities, and reduced oxidative damage. Transcriptome profiling revealed 1,599 species-specific expressed genes and 3,379 orthologous genes with interspecies expression divergence. Several key defense-related pathways, such as MAPK signaling and plant-pathogen interaction, contained critical node genes that exhibited species-specific regulation, potentially contributing to the enhanced resistance of C. ficifolia. This global divergence in gene expression was associated with distinct metabolic shifts, leading to the specific activation of defense-related metabolic pathways in C. ficifolia and the subsequent accumulation of protective compounds such as brassinosteroids, phenylpropanoids, and flavonoids. These findings indicate that C. ficifolia's superior FOC resistance is not attributable to a single factor but emerges from a sophisticated orchestration of gene expression and metabolic output. This study provides novel molecular insights into Fusarium wilt resistance and offers candidate genes and metabolic targets for breeding disease-resistant cucurbit crops.

The versatile and pivotal roles of the phytohormone auxin in regulating plant growth and development are typically linked to its directional transport, relying on the polarized PIN-FORMED (PIN) auxin exporters at the plasma membrane (PM). For decades, auxin has been proposed to promote PIN polarization, generating self-regulatory feedback mediating much of plant development, but mechanistic insight into this regulation is lacking. Here, we uncover an auxin-induced protein complex at the PM, containing auxin co-receptors transmembrane kinases (TMKs) and PIN1 auxin exporter, as the core machinery that underlies this feedback regulation. Auxin promotes PIN1 phosphorylation by TMKs, modulating PIN1 polarization and transport activity. We also provide evidence that PIN1-exported extracellular auxin is crucial for TMK activation and cell elongation, thus forming the simplest two-element self-regulatory feedback circuit. Thus, these findings offer direct mechanistic insights into a potential self-organizing circuit for auxin signaling and transport to ensure proper plant development in Arabidopsis.

The NAM, ATAF, and CUC (NAC) transcription factors represent a major class of plant-specific transcription factors that regulate plant growth, development, and responses to various biotic and abiotic stresses. Despite their importance, limited information exists about this gene family in wolfberry (Lycium barbarum), a valuable traditional Chinese medicinal plant widely cultivated in northwest China. In this study, 107 LbaNAC genes were identified from the wolfberry genome and found to be unevenly distributed across 12 chromosomes. These LbaNAC genes were clustered into 18 subfamilies, with motif composition and gene structure showing high consistency with their phylogenetic relationships. A total of 192 orthologous gene pairs were identified between wolfberry and tomato, potato, Arabidopsis thaliana, and rice, respectively. Gene duplication analysis revealed that dispersed duplication was a major driver in the expansion of the LbaNAC gene family, while the analysis of the nonsynonymous (Ka) to synonymous (Ks) substitution rates confirmed that purifying selection has been the predominant evolutionary force acting on these genes. Cis-acting element analysis showed that their promoters harbor elements associated with growth, metabolism, and various stress responses. Furthermore, correlation analysis demonstrated that the expression profiles of LbaNAC001, 027, 043, 051, 053, and 080 were significantly and positively correlated with the dynamic changes in glucose, fructose, and sucrose contents in wolfberry fruits. Furthermore, quantitative real-time PCR validation of the selected LbaNAC genes confirmed that their expression patterns were consistent with the transcriptome data. Subcellular localization and transcriptional activation analyses revealed that LbaNAC027 is a nucleus-localized transcriptional activator. This study identifies potential LbaNACs involved in wolfberry fruit sugar metabolism, providing a theoretical foundation for elucidating their regulatory mechanisms.

The coordinated development of achenes and receptacles in strawberry is critical for seed dispersal and fruit quality, yet the underlying molecular mechanisms remain poorly characterized. Utilizing RNA-seq analysis during the ripening transition stage, we identified pronounced transcriptomic divergence between achenes and receptacles, with receptacles exhibiting more dynamic gene expression shifts. Intriguingly, a substantial subset of differentially expressed genes (DEGs) displayed antagonistic expression patterns between these tissues, including the cytokinin degradation gene cytokinin oxidase/dehydrogenase 1 (FvCKX1), which was highly expressed in both tissues but with opposing temporal trends. Functional interrogation via transient silencing and overexpression revealed a tissue-specific regulatory role for FvCKX1. RNA interference (RNAi) suppression of FvCKX1 significantly enhanced receptacle expansion but delayed achene maturation, whereas overexpression inhibited receptacle growth while accelerating achene ripening. Abscisic acid (ABA), which positively regulates fruit enlargement, was elevated in FvCKX1 RNAi receptacles and notably reduced in overexpression fruits, indicating that FvCKX1 might negatively modulate ABA synthesis during strawberry fruit development. Our results demonstrate that FvCKX1 may function as a key regulator mediating the coordinated development between achenes and receptacles in strawberry.

Background: A recent study reported that a deficiency of Col5a3 reduces dermal fat. However, the regulatory mechanism of the Col5a3 gene on adipose deposition remains unclear. Methods: In this study, we assessed the effects of Col5a3 interference on the proliferation and differentiation of 3T3-L1 preadipocytes through CCK-8, EdU staining, cell cycle detection, RT-qPCR, Western blot, a triglyceride assay, and Oil Red O staining. RNA-seq was then performed on differentiated adipocytes to identify key differentially expressed genes (DEGs) and signaling pathways. Results: Col5a3 interference significantly promoted the proliferation of 3T3-L1 cells but inhibited their differentiation. RNA-seq analysis identified 368 DEGs, with the most significant enrichment observed in the oxidative phosphorylation pathway. Conclusions: This study demonstrates the regulatory role of Col5a3 in the proliferation and differentiation of preadipocytes, identifying various genes regulated by Col5a3 in adipogenesis. We speculate that Col5a3 may influence adipogenesis through the oxidative phosphorylation pathway in 3T3-L1 cells. The findings help gain a better understanding of the molecular mechanisms underlying fat deposition and obesity-related metabolic diseases.

This study investigated the intercropping system of wolfberry with forage species, white clover, ryegrass, and mangold by analyzing root exudates extracted via hydroponic methods and their influences on seed germination, seedling growth, and root rot pathogens. This research demonstrates the root exudate-mediated interspecific mechanisms in wolfberry -forage intercropping systems, providing a theoretical foundation for leveraging allelopathy to optimize sustainable agroecological practices. It finds that wolfberry root exudates significantly promoted seed germination in white clover, mangold, and ryegrass, while inhibiting alfalfa germination. Forage root exudates slightly suppressed wolfberry seed germination but markedly enhanced seedling growth, with alfalfa and white clover showing the strongest promotion. Secondly, the primary pathogens causing wolfberry root rot were identified as Mucor circinelloides, Rhizopus arrhizus, Fusarium solani, and F. oxysporum. mangold root rot was predominantly associated with F. solani, Aspergillus niger, and Penicillium solitum. Thirdly, wolfberry root exudates containing autotoxic compounds significantly promoted the expansion of self-associated Fusarium lesions. Legume exudates (alfalfa, white clover) stimulated lesion expansion in Rhizopus and A. niger but suppressed Fusarium mycelial growth. Lastly, wolfberry intercropped with mangold or ryegrass effectively suppressed soil-borne diseases, while legume intercrops (alfalfa, white clover) potentially reduced disease risks by modulating pathogen community structures through allelopathic interactions.

Black wolfberry(Lycium ruthenicum Murr.)is an important plant for ecological preservation.In addition,its fruits are rich in anthocyanins and have important edible and medicinal value.However,a high-quality chromosome-level genome for this species is not yet available,and the regulatory mechanisms involved in the biosynthesis of anthocyanins are unclear.In this study,haploid material was used to assemble a high-quality chromosome-level reference genome of Lycium ruthenicum,resulting in a genome size of 2272 Mb with contig N50 of 92.64 Mb,and 38 993 annotated gene models.In addition,the evolution of this genome and large-scale variations compared with the Ningxia wolfberry Lycium barbarum were determined.Importantly,homology annotation identified 86 genes involved in the regulatory pathway of anthocyanin biosynthesis,five of which[LrCHS1(evm.TU.Chr05.295),LrCHS2(evm.TU.Chr09.488),LrAOMT(evm.TU.Chr09.809),LrF3'5'H(evm.TU.Chr06.177),and LrAN2.1(evm.TU.Chr05.2618)]were screened by differential expression analysis and correlation analysis using a combination of transcriptome and metabolome testing.Overexpression of these genes could significantly up-or downregulate anthocyanin-related metabolites.These results will help accelerate the functional genomic research of L.ruthenicum,and the elucidation of the genes involved in anthocyanin synthesis will be beneficial for breeding new varieties and further exploring its ecological conservation potential.

Spawning diversity plays an essential role in fish survival and reproduction, which contributes to the exceptional diversity of teleosts among vertebrates. Different zona radiata structures reflect the adaptability of fish to the environment of spawning and early embryonic development. The morphological and transcriptional characteristics of fish follicle development between different spawning habits, particularly the zona radiata variations, have been poorly documented. In this study, we integrated histology and transcriptomics to investigate the differences in the zona radiata structure and gene expression profiles among follicles from different spawning habits of Culter alburnus. Our results revealed that stage Ⅲ was the crucial period for zona radiata thickening and structure differentiation. Transcriptomic analyses of adhesive and semi-buoyant eggs at stage Ⅲ revealed a significant upregulation of genes involved in glycoprotein synthesis, extracellular matrix formation, and regulation of protease activity in adhesive eggs, such as the wfdc and a2ml gene family. This upregulation likely underpins the thicker zona radiata in adhesive eggs, facilitating their attachment to substrates. This study represents the first elucidation of the ultrastructure of the zona radiata and gene expression patterns in different developmental stages of adhesive and semi-buoyant eggs of Culter alburnus, offering new perspectives for aquaculture research in understanding fish reproductive adaptations.

Root exudates play a critical role in enabling plants to respond to environmental stresses and mediate information exchange within the rhizosphere. These compounds regulate plant–rhizosphere interactions and significantly influence the structural and functional properties of the rhizosphere micro-ecosystem. Under continuous cropping systems, allelochemicals derived from root exudates progressively accumulate in the root zone, thereby contributing to the development of continuous cropping obstacles. In this study, root exudates were collected from wolfberry (Lycium barbarum L.) and four forages under controlled conditions to test their effects on seed germination and seedling growth in mangold (Betu vulgaris L.) and wolfberry, as well as on the root rot pathogen. Our research shows that forage root exudates could promote wolfberry seedling growth. White clover (Trifolium repens L.) and alfalfa (Medicago sativa L.), especially, could have their growth increased by up to 61% and 90% (p < 0.05). Wolfberry root exudates could promote the seed germination and seedling growth of white clover and mangold, the seed germination of Ryegrass (Lolium perenne L.), and the seedling growth of alfalfa. In addition, mangold root rots were identified as Molds, Aspergillus niger, and Fusarium solani and wolfberry root rots were Mucor cirrus, Rhizopus, Fusarium oxysporum, and Fusarium solani. What is more, wolfberry root exudates could promote Fusarium plaque expansion and mycelial growth. Ryegrass inhibited the growth of Mucor, Fusarium putrum, and oxysporum, and alfalfa and white clover promoted the plaque expansion of Rhizopus, Aspergillus niger, and Fusarium fulcrum, but inhibited the mycelial growth of related pathogens; mangold root exudates could inhibit wolfberry root rot, which affects interspecific relationships. This study provides robust technical support for elucidating interspecific relationships and promoting the development and application of the wolfberry-forage intercropping system.

Species of the genus Rosa are among the commercially important exploited groups of ornamental plants in the world. Despite its wide application, the phylogenetic placement of many subgenera and sections of the genus is still unresolved due to hybridization, polyploidization, incomplete lineage sorting, low differentiation among the genus, and even their complex history of cultivation and breeding. Through more comprehensive taxon sampling, this study analyzed 18 representative Rosa plastid genomes, including 13 new sequences, to elucidate their phylogeny within the genus as well as the variation patterns in the plastid genomes. The results revealed that the length of 106 complete Rosa plastomes varied between 156,333 bp and 157,396 bp, with closed circular tetrad structures of the SSC and LSC regions separated by two IR regions. Comparative analysis subsequently revealed high similarity in the total GC content, gene order and PCGs (79) of Rosa plastomes. No significant contraction or expansion of the IR boundary was noted in most Rosa species, except for the trnH-GUG gene, which is found mainly in the LSC region but crosses the IRa/LSC boundary in basal taxa of the Rosa phylogenetic tree. Abundant SSRs (73–87) and long repeat sequences (36–52) were detected in Rosa plastomes, and most of these repeats could be found within the IGS region. Eight IGS regions were identified as highly variable regions, which provides potential information for developing molecular markers. Nineteen genes were discovered to have undergone significant positive selection. Phylogenetic analyses based on PCGs and complete plastome sequences indicated that the genus Rosa was monophyletic well grouped into seven major clades with high bootstrap support. Most previously-defined subgenera and sections were paraphyletic. By assembling the largest known dataset of Rosa plastomes, the plastid genomic features across the genus were comprehensively studied before reconstructing a phylogenetic tree with a well-resolved backbone. However, the current study also shows the limitations of using plastomes to infer the phylogeny of some difficult taxa, and combining plastome, morphological and nuclear data together is recommended. This work offers valuable and basic sequence information for phylogenetic studies, species identification, Rosa species breeding and molecular genetics studies.

Citrus Huanglongbing (HLB) is the most catastrophic citrus disease worldwide. SEC-dependent effectors (SDEs) play prominent roles in HLB pathogenesis, and 86 were predicted from the genome of Candidatus Liberibacter asiaticus. Nevertheless, little is known about the comprehensive picture of effector action mechanisms. In this study, RNA-seq was performed to explore the gene expression profiling of transgenic citrus plants expressing a CLas SDE, CLIBASIA_00185 (0185-OE). A total of 6,506 differentially expressed genes (DEGs) were identified between 0185-OEs and the wild-type (WT) control through RNA-seq. Gene ontology (GO) analysis indicated that molecular functions associated with cellular process, cell part, binding, and catalysis activity were affected. Kyoto encyclopedia of genes and genomes (KEGG) pathway analysis revealed that DEGs were enriched in pathways including primary and secondary metabolisms. Further analysis demonstrated that DEGs implicated in sugar metabolism, phenylpropanoid biosynthesis, and endocytosis pathway were markedly induced in 0185-OE group compared to those in WTs. Ten genes were chosen to verify RNA-seq data with qRT-PCR, and their expression patterns were in good agreement with those of RNA-seq. The transcriptomic analysis demonstrated that CLIBASIA_00185 (CLas0185) governed sugar metabolism, phenylpropanoid biosynthesis and endocytosis for pathogen survival and development. The results determined a prominent role of CLas0185 in HLB pathogenicity that could be a target for disease management.

Forage cover crops have the potential to improve soil quality and orchard productivity, but their effects on wolfberry (Lycium barbarum L.) plants are still unclear. In this study, we conducted field and greenhouse experiments between 2019 and 2021, with 10 forage species as cover crops. We observed the growth, yield, fruit quality, and photosynthetic characteristics of wolfberry plants, as well as the occurrence of plant diseases and pests. Based on averaged data for all forage species, cover cropping facilitated plant growth, maintained fruit yield, and promoted leaf photosynthesis in wolfberry compared to monocropping. This was exemplified by a notable increase in the branch number of wolfberry plants under ryegrass treatment, with marginal increase in branch length under evergreen grass (lvyuan 5) and mangold treatments. Cover cropping additionally improved wolfberry quality through increasing carotenoid, flavonoid, and ascorbic acid contents by 21%, 53%, and 127%, respectively (P < 0.05). The presence of mangold, alfalfa, sweet sorghum, ryegrass, and feather grass reduced powdery mildew-induced leaf damage in wolfberry plants by 69% (P < 0.05). When alfalfa, feather grass, and ryegrass were used, the risk of aphid infestation was lowered by 67% (P < 0.05). Collectively, the results indicated that mangold, ryegrass, and alfalfa were the optimal cover crops for sustainable wolfberry production in the study area. The use of appropriate forage cover crops enhanced plant growth and fruit quality of wolfberry by stimulating photosynthetic capacity and biotic stress resistance.

In the context of modern pig farming, the central role of boars is underscored by large-scale centralized breeding and the widespread application of artificial insemination techniques. However, previous studies and breeding programs have focused mainly on product efficiency traits, such as growth rate, lean meat yield, and litter size, often neglecting boar semen traits. In this study, we estimated the genetic parameters and assessed the genomic prediction accuracy of boar semen traits with phenotypes evaluated from 274,332 ejections in a large population consisting of 2467 Duroc boars. Heritability of sperm morphological abnormality rate (ABN), fresh semen volume (VOL), sperm concentration (DEN), and motility (MOT) were estimated to be 0.43, 0.22, 0.23, and 0.16, respectively. GBLUP achieved a moderate predictive ability of semen traits, with a range of 0.32-0.50. Incorporating gene interactions indicated by the KEGG pathways (biBLUP) significantly improved predictive accuracy over the classical additive model (GBLUP) and epistatic model (RKHS). Moreover, biBLUP showed an improvement from 9.50% to 20.10% among the studied traits compared with GBLUP, with the greatest improvement (0.40 vs. 0.48) observed in sperm morphological abnormality rate. In conclusion, moderate to low heritability was estimated for the Duroc boar semen traits. Genomic prediction was able to achieve moderate accuracy, with a range from 0.32 to 0.56, for the studied traits. Considering gene interactions within KEGG pathways enhanced the predictive ability of boar semen traits.

Sex-biased genes offer insights into the evolution of sexual dimorphism. Sex-biased genes, especially those with male bias, show elevated evolutionary rates of protein sequences driven by positive selection and relaxed purifying selection in animals. Although rapid sequence evolution of sex-biased genes and evolutionary forces have been investigated in animals and brown algae, less is known about evolutionary forces in dioecious angiosperms. In this study, we separately compared the expression of sex-biased genes between female and male floral buds and between female and male flowers at anthesis in dioecious Trichosanthes pilosa (Cucurbitaceae). In floral buds, sex-biased gene expression was pervasive, and had significantly different roles in sexual dimorphism such as physiology. We observed higher rates of sequence evolution for male-biased genes in floral buds compared to female-biased and unbiased genes. Male-biased genes under positive selection were mainly associated with functions to abiotic stress and immune responses, suggesting that high evolutionary rates are driven by adaptive evolution. Additionally, relaxed purifying selection may contribute to accelerated evolution in male-biased genes generated by gene duplication. Our findings, for the first time in angiosperms, suggest evident rapid evolution of male-biased genes, advance our understanding of the patterns and forces driving the evolution of sexual dimorphism in dioecious plants.

Short-chain dehydrogenases/reductases (SDRs) are ubiquitously distributed across diverse organisms and play pivotal roles in the growth, as well as endogenous and exogenous metabolism of various substances, including drugs. The expression levels of SDR genes are reportedly upregulated in the fenpropathrin (FEN)-resistant (FeR) strain of Tetranychus cinnabarinus. However, the functions of these SDR genes in acaricide tolerance remain elusive. In this study, the activity of SDRs was found to be significantly higher (2.26-fold) in the FeR strain compared to the susceptible strain (SS) of T. cinnabarinus. A specific upregulated SDR gene, named SDR112C1, exhibited significant overexpression (3.13-fold) in the FeR population compared with that in the SS population. Furthermore, the expression of SDR112C1 showed a significant increase in the response to FEN induction. Additionally, knockdown of the SDR112C1 gene resulted in decreased SDR activity and reduced mite viability against FEN. Importantly, heterologous expression and in vitro incubation assays confirmed that recombinant SDR112C1 could effectively deplete FEN. Moreover, the overexpression of the SDR112C1 gene in Drosophila melanogaster significantly decreased the toxicity of FEN to transgenic fruit flies. These findings suggest that the overexpression of SDR SDR112C1 is a crucial factor contributing to FEN tolerance in T. cinnabarinus. This discovery not only enhances our understanding of SDR-mediated acaricide tolerance but also introduces a new family of detoxification enzymes to consider in practice, beyond cytochrome P450s, carboxyl/choline esterases and glutathione S-transferases.

Asian citrus psyllid (ACP, Diaphorina citri) is the major vector of Candidatus Liberibacter asiaticus (CLas), which is a bacterial pathogen causing the devastating citrus Huanglongbing (HLB) disease. Diaphorina citri is known to carry CLas in a persistent and propagative manner. Some studies have suggested that CLas may use the vesicular structures of D. citri cells as its propagation organelles. However, the mechanisms by which CLas enters the D. citri cells and how vesicle-mediated trafficking is involved remain unclear. In this study, we monitored the titer change of CLas in D. citri nymphs during the process of CLas acquisition from feeding on infected citrus plants. We found that the titer of CLas increased with the acquisition access period. After infection, there was a significant upregulation in the expression of several vesicular transport-related genes in D. citri. The titer of CLas was significantly reduced in the midgut and whole insect body when endocytosis and the endosome network in D. citri were inhibited. Furthermore, silencing the D. citri clathrin-heavy chain gene also led to a reduction in the CLas titer in D. citri. These results suggest that CLas infection upregulates the genes related to vesicular transport in D. citri, which facilitates the invasion of endocytosis-dependent pathogens.

The Ningxiang pig, one of the well-known Chinese native pig breeds, has the advantages of tender meat, high intramuscular fat (IMF) content, and roughage tolerance, compared to the commercial lean pig breeds. The genetic basis for complex traits in Ningxiang pigs has been previously studied through other genetic markers, such as Single Nucleotide Polymorphism (SNP), while the characteristics of copy number variation (CNV) and the selection signal have not been investigated yet. In this study, GGP 50 k genotyping data of 2242 Ningxiang pigs (NX) and 1137 Duroc pigs (Duroc) were involved in CNV atlas construction and selection signals identification. Annotations of genes and quantitative trait locus (QTLs) were performed on the target candidate regions, as follows: (1) 162 CNVs were detected in Ningxiang pigs, while 326 CNVs were detected in Duroc pigs, and there are 21 copy number variation regions (CNVRs) shared between them; (2) The CNVRs of Duroc are more abundant, with 192 CNVRs, accounting for 1.61% of the entire genome, while those of Ningxiang pigs only have 98 CNVRs, accounting for 0.49%; (3) The QTLs annotated on CNVs and selected regions of Ningxiang pigs were mainly associated with meat quality and fertility. In contrast, the Duroc QTLs’ notes relate primarily to the carcass and immunity, and explain why they have a higher slaughter rate and immunity; (4) There is a presence of high-frequency acquired CNVs, specifically in Ningxiang pigs, with 24 genes significantly enriched in the sensory receptor-related pathway in this region; (5) Based on the CNVs atlas, candidate genes such as 3 inositol 1,4,5-triphosphate receptor, type 3 (ITPR3), forkhead box protein K2 (FOXK2), G-protein coupled estrogen receptor 1 (GPER1), Glyceraldehyde 3-phosphate dehydrogenase (GAPDH), triosephosphate isomerase 1 (TPI1), and other candidate genes related to fat deposition and differentiation were screened. In general, this study improved our knowledge about copy number variation and selection signal information of Ningxiang pigs, which can not only further explain the genetic differences between Chinese native and Western commercial pig breeds, but also provide new materials for the analysis of the genetic basis of complex traits.

Huanglongbing (HLB) is a global devastating citrus disease that is mainly caused by "Candidatus Liberibacter asiaticus" (CLas). It is mostly transmitted by the insect Asian citrus psyllid (ACP, Diaphorina citri) in a persistent and proliferative manner. CLas traverses multiple barriers to complete an infection cycle and is likely involved in multiple interactions with D. citri. However, the protein-protein interactions between CLas and D. citri are largely unknown. Here, we report on a vitellogenin-like protein (Vg_VWD) in D. citri that interacts with a CLas flagellum (flaA) protein. We found that Vg_VWD was upregulated in CLas-infected D. citri. Silencing of Vg_VWD in D. citri via RNAi silencing significantly increased the CLas titer, suggesting that Vg_VWD plays an important role in the CLas-D. citri interaction. Agrobacterium-mediated transient expression assays indicated that Vg_VWD inhibits BAX- and INF1-triggered necrosis and suppresses the callose deposition induced by flaA in Nicotiana benthamiana. These findings provide new insights into the molecular interaction between CLas and D. citri.

BACKGROUND:Terpenoids play essential roles in plant defense against biotic stresses. In Citrus species, the monoterpene linalool mediates resistance against citrus canker disease caused by the gram-negative bacteria Xanthomonas citri subsp. citri (Xcc). Previous work had associated linalool contents with resistance; here we characterize transcriptional responses of linalool synthase genes.RESULTS:Leaf linalool contents are highly variable among different Citrus species. "Dongfang" tangerine (Citrus reticulata), a species with high linalool levels was more resistant to Xcc than "Shatian" pummelo (C. grandis) which accumulates only small amounts of linalool. The coding sequences of the major leaf-expressed linalool synthase gene (STS4) are highly conserved, while transcript levels differ between the two Citrus species. To understand this apparent differential transcription, we isolated the promoters of STS4 from the two species, fused them to a GUS reporter and expressed them in Arabidopsis. This reporter system revealed that the two promoters have different constitutive activities, mainly in trichomes. Interestingly, both linalool contents and STS4 transcript levels are insensitive to Xcc infestation in citrus plants, but in these transgenic Arabidopsis plants, the promoters are activated by challenge of a bacterial pathogen Pseudomonas syringae, as well as wounding and external jasmonic acid treatment.CONCLUSIONS:Our study reveals variation in linalool and resistance to Xcc in citrus plants, which may be mediated by different promoter activities of a terpene synthase gene in different Citrus species.