Host Plant Research Articles

Shedding light on bacteria–host interactions with the aid of TnSeq approaches

ABSTRACT Bacteria are highly adaptable and grow in diverse niches, where they often interact with eukaryotic organisms. These interactions with different hosts span the entire spectrum from symbiosis to pathogenicity and thus determine the lifestyle of the bacterium. Knowledge of the genetic determinants involved in animal and plant host colonization by pathogenic and mutualistic bacteria is not only crucial to discover new drug targets for disease management but also for developing novel biostimulant strategies. In the last decades, significant progress in genome-wide high-throughput technologies such as transposon insertion sequencing has led to the identification of pathways that enable efficient host colonization. However, the extent to which similar genes play a role in this process in different bacteria is yet unclear. This review highlights the commonalities and specificities of bacterial determinants important for bacteria–host interaction.

Ectomycorrhizal fungi alter soil food webs and the functional potential of bacterial communities.

Most of Earth's trees rely on critical soil nutrients that ectomycorrhizal fungi (EcMF) liberate and provide, and all of Earth's land plants associate with bacteria that help them survive in nature. Yet, our understanding of how the presence of EcMF modifies soil bacterial communities, soil food webs, and root chemistry requires direct experimental evidence to comprehend the effects that EcMF may generate in the belowground plant microbiome. To this end, we grew Pinus muricata plants in soils that were either inoculated with EcMF and native forest bacterial communities or only native bacterial communities. We then profiled the soil bacterial communities, applied metabolomics and lipidomics, and linked omics data sets to understand how the presence of EcMF modifies belowground biogeochemistry, bacterial community structure, and their functional potential. We found that the presence of EcMF (i) enriches soil bacteria linked to enhanced plant growth in nature, (ii) alters the quantity and composition of lipid and non-lipid soil metabolites, and (iii) modifies plant root chemistry toward pathogen suppression, enzymatic conservation, and reactive oxygen species scavenging. Using this multi-omic approach, we therefore show that this widespread fungal symbiosis may be a common factor for structuring soil food webs.IMPORTANCEUnderstanding how soil microbes interact with one another and their host plant will help us combat the negative effects that climate change has on terrestrial ecosystems. Unfortunately, we lack a clear understanding of how the presence of ectomycorrhizal fungi (EcMF)-one of the most dominant soil microbial groups on Earth-shapes belowground organic resources and the composition of bacterial communities. To address this knowledge gap, we profiled lipid and non-lipid metabolites in soils and plant roots, characterized soil bacterial communities, and compared soils amended either with or without EcMF. Our results show that the presence of EcMF changes soil organic resource availability, impacts the proliferation of different bacterial communities (in terms of both type and potential function), and primes plant root chemistry for pathogen suppression and energy conservation. Our findings therefore provide much-needed insight into how two of the most dominant soil microbial groups interact with one another and with their host plant.

New records of Pestalotioid species associated with leaf spot disease on Camellia sinensis from northern Thailand

Camellia sinensis (L.) Kuntze var. assamica (Miang tea) is widely distributed in northern Thailand due to its traditional and industrial attributes, including black tea and Miang production. In this study, two Pestalotioid taxa associated with C. sinensis leaf spots were collected in Mae Taeng district, Chiang Mai Province, Thailand. Species delineation was based on the evidence from morphological and multi-locus phylogenies using ITS, tub2 and tef1-α. Neopestalotiopsis saprophytica is herein reported as a new record on Camellia sinensis, while Pseudopestalotiopsis chinensis is recorded as a new geographical record from Thailand. The findings of this research have the potential to offer fresh insights into the two previously documented species within the existing fungal community associated with C. sinensis in Thailand. This, in turn, could enhance our comprehension of their interactions with the host plant in the times ahead.

The Impact of Aboveground Epichloë Endophytic Fungi on the Rhizosphere Microbial Functions of the Host Melica transsilvanica.

In nature, the symbiotic relationship between plants and microorganisms is crucial for ecosystem balance and plant growth. This study investigates the impact of Epichloë endophytic fungi, which are exclusively present aboveground, on the rhizosphere microbial functions of the host Melica transsilvanica. Using metagenomic methods, we analyzed the differences in microbial functional groups and functional genes in the rhizosphere soil between symbiotic (EI) and non-symbiotic (EF) plants. The results reveal that the presence of Epichloë altered the community structure of carbon and nitrogen cycling-related microbial populations in the host's rhizosphere, significantly increasing the abundance of the genes (porA, porG, IDH1) involved in the rTCA cycle of the carbon fixation pathway, as well as the abundance of nxrAB genes related to nitrification in the nitrogen-cycling pathway. Furthermore, the presence of Epichloë reduces the enrichment of virulence factors in the host rhizosphere microbiome, while significantly increasing the accumulation of resistance genes against heavy metals such as Zn, Sb, and Pb. This study provides new insights into the interactions among endophytic fungi, host plants, and rhizosphere microorganisms, and offers potential applications for utilizing endophytic fungi resources to improve plant growth and soil health.

Colonization of Piriformospora indica enhances rice resistance against the brown planthopper Nilaparvata lugens.

Piriformospora indica is an endophytic fungus that can promote the growth and confer resistance against diverse stresses in host plants by root colonization. However, the effects of P. indica colonization on improving plant resistance to insect pests are still less explored. The brown planthopper (BPH) Nilaparvata lugens is a serious monophagous pest that causes extensive damage to rice plants. Here, we aimed to evaluate the effects of P. indica colonization on rice resistance against BPH. The colonization of P. indica in rice roots resisted damage from BPH. Age-stage, two-sex life table analyses showed that feeding on P. indica-colonized rice plants affected BPH's female adult longevity, oviposition period, fecundity, population parameters and population size. BPH female adults feeding on P. indica-colonized plants excreted less honeydew. P. indica colonization remarkably increased the duration of np, N2, and N3 waveform, as well as the occurrences of N1 and N2, and decreased the duration of N4-b for BPH on rice plants. Meanwhile, the weight of BPH on the colonized plants was significantly lower than the control. In addition, the feeding and oviposition preferences of BPH to P. indica-colonized plants were reduced. qRT-RCR analyses revealed that P. indica colonization induced the expressions of jasmonic acid (JA)- and salicylic acid (SA)-related genes in rice plants. P. indica colonization can reduce BPH performance on rice plants with potential inhibitory effects on population growth. Collectively, these results support the potential for endophytically colonized P. indica as an effective strategy to improve insect resistance of crops. © 2024 Society of Chemical Industry.

A meta-analysis on global change drivers and the risk of infectious disease.

Anthropogenic change is contributing to the rise in emerging infectious diseases, which are significantly correlated with socioeconomic, environmental and ecological factors1. Studies have shown that infectious disease risk is modified by changes to biodiversity2-6, climate change7-11, chemical pollution12-14, landscape transformations15-20 and species introductions21. However, it remains unclear which global change drivers most increase disease and under what contexts. Here we amassed a dataset from the literature that contains 2,938 observations of infectious disease responses to global change drivers across 1,497 host-parasite combinations, including plant, animal and human hosts. We found that biodiversity loss, chemical pollution, climate change and introduced species are associated with increases in disease-related end points or harm, whereas urbanization is associated with decreases in disease end points. Natural biodiversity gradients, deforestation and forest fragmentation are comparatively unimportant or idiosyncratic as drivers of disease. Overall, these results are consistent across human and non-human diseases. Nevertheless, context-dependent effects of the global change drivers on disease were found to be common. The findings uncovered by this meta-analysis should help target disease management and surveillance efforts towards global change drivers that increase disease. Specifically, reducing greenhouse gas emissions, managing ecosystem health, and preventing biological invasions and biodiversity loss could help to reduce the burden of plant, animal and human diseases, especially when coupled with improvements to social and economic determinants of health.

Influence of sticky trap color, host plant species, and weather factors on the population dynamics of thrips species in Southern Ghana.

It is essential to correctly identify and keep track of the abundance of thrips species on infested host crops to understand their population dynamics and implement control measures promptly. The current study was conducted to evaluate the performance of sticky traps in monitoring thrips species in exporters' eggplant and chili farms and to assess the impact of weather factors on thrips population dynamics. Thrips species were monitored using blue, yellow, and white sticky traps on chili and eggplant farms in Tuba, respectively, in 2020 and 2021. Each field was divided into 8 blocks, and in each replicate, all colors representing 3 treatments were randomly tied to stakes at the center of the respective crop. Data loggers were installed to record hourly weather variables. Three thrips species [Thrips parvispinus Karny (Thysanoptera: Thripidae), Franklinella schultzei Trybom (Thysanoptera: Thripidae), and Thrips tabaci Lindeman (Thysanoptera: Thripidae)] were identified from both farms and the different species showed varied attractiveness to trap color for both seasons, with white proving more attractive to T. parvispinus. The population dynamics of the species varied significantly with the season and weather but not with the crop. Optimum temperatures (28-31 °C) and relative humidity (60%-78%) showed a positive linear relationship between the trapped insects with temperature and RH, while extreme temperatures (35 °C) negatively affected their abundance. All sticky trap colors attracted several nontarget organisms; however, yellow colors had higher populations, including the predator, Orius insidiosus. White sticky traps are recommended for inclusion in the country-wide monitoring for thrips, especially T. parvispinus.

Plant virus transmission during seed development and implications to plant defense system.

Most plants produce large amounts of seeds to disperse their progeny in the environment. Plant viruses have evolved to avoid plant resistance mechanisms and use seeds for their dispersal. The presence of plant pathogenic viruses in seeds and suppression of plant host defenses is a major worldwide concern for producers and seed companies because undetected viruses in the seed can represent a significant threat to yield in many economically important crops. The vertical transmission of plant viruses occurs directly through the embryo or indirectly by getting in pollen grains or ovules. Infection of plant viruses during the early development of the seed embryo can result in morphological or genetic changes that cause poor seed quality and, more importantly, low yields due to the partial or ubiquitous presence of the virus at the earliest stages of seedling development. Understanding transmission of plant viruses and the ability to avoid plant defense mechanisms during seed embryo development will help identify primary inoculum sources, reduce virus spread, decrease severity of negative effects on plant health and productivity, and facilitate the future of plant disease management during seed development in many crops. In this article, we provide an overview of the current knowledge and understanding of plant virus transmission during seed embryo development, including the context of host-virus interaction.

Multiple factors influenced the aggregation behavior of adult Eucryptorrhynchus scrobicuatus (Coleoptera: Curculionidae).

Eucryptorrhynchus scrobiculatus (Motschulsky) (Coleoptera: Curculionidae) is a notorious pest of Ailanthus altissima (Mill.) Swingle (Sapindales: Simaroubaceae). E. scrobiculatus adults typically aggregate under leaves and in soil crevices at the base of A. altissima in the field. We hypothesize that the environmental factors and conspecific signals determine their aggregation behavior. To test this, we investigated adult numbers in light-exposed and shaded areas of the sample trees and conducted experiments in both field and lab settings. Results revealed that (i) greater adult distribution in shaded areas; (ii) significant influence of temperature and illumination on aggregation tendency in the field; (iii) no gender-based difference in aggregation degree and maximum aggregation between light and dark; (iv) the host plant triggering the aggregation tendency, negatively affected in the absence; (v) the aggregation tendency of E. scrobiculatus weakened with the temperature gradually changing to ordinary temperature; and (vi) mutual attraction and chemical attraction between males and females. Thus, the aggregation behavior was influenced by factors including temperature, light intensity, host plant, and conspecific signals, but light's role was not obvious in the lab.

Catalog of the Chrysomelinae (Coleoptera: Chrysomelidae) deposited in the entomological collections of the Museu Paraense Emílio Goeldi (MPEG) and the Universidade do Estado do Pará (UEPA), Belém, Brazil

A comprehensive catalog is provided for most leaf beetles belonging to the Chrysomelinae subfamily, which are housed in the collections of two institutions in the state of Pará, located in northern Brazil: The Museu Paraense Emílio Goeldi (MPEG) and the Universidade do Estado do Pará (UEPA). The catalog includes detailed geographic distribution data for all species, along with new records and photographs (including two paratypes of Cryptostetha pereirai Bechyně, 1958, with descriptions of the aedeagus and spermatheca). Furthermore, information is provided on host plants, parasites, parasitoids, and predators associated with certain species.

Effect of Pelargonium graveolens essential oil and cyantraniliprole on the feeding behavior of Bemisia tabaciMED

AbstractThe sweet potato whitefly, Bemisia tabaci MED (Gennadius) (Hemiptera: Aleyrodidae), is highly harmful to solanaceous crops. The use of essential oils (EOs) is promising for the management of several insect pests, promoting both lethal and sublethal effects. This study aimed to evaluate the effects of sublethal concentrations of Pelargonium graveolens L'Her (Geraniaceae) EO on the feeding behavior of B. tabaci MED on tomato plants (Solanum lycopersicum L., Solanaceae). For this research, the electrical penetration graph (EPG) technique was used to monitor whitefly stylet activities on their host plants. Two sets of plants were previously sprayed with two concentrations of EO (the LC25 and LC50, which were determined in a mortality test), a third set was treated with the insecticide cyantraniliprole, and a fourth set received a control treatment. Our results indicate that the insecticide cyantraniliprole and the EO could both reduce the stylet feeding activity of B. tabaci MED, as well as reduce the number and duration of phloem sap ingestion events (waveform E2), which could avoid or reduce the transmission of viruses. Thus, the application of sublethal concentrations of P. graveolens EO, as well as exposure to cyantraniliprole, negatively affected the feeding behavior of B. tabaci MED. This information may contribute to the management of this pest and the reduction of the incidence of viruses in tomato production.

The endemic Hawaiian mealybug genus Phyllococcus Ehrhorn, 1916 (Hemiptera: Coccomorpha: Pseudococcidae): redescription of the type species and description of a new species on an endangered host plant, Cryptocarya mannii (Lauraceae)

The endemic Hawaiian mealybug genus Phyllococcus Ehrhorn (Hemiptera: Coccomorpha: Pseudococcidae) was erected in 1916 as a monotypic genus for a gall-inducing mealybug collected on the island of Oahu on Urera sandwicensis (now referred to genus Touchardia) (Urticaceae) in 1911. The species induces deep horn-shaped galls on the leaves of the host plant. Here we redescribe the adult female and adult male of Ph. oahuensis (Ehrhorn) and designate a lectotype; and we report a new record for Ph. oahuensis from the island of Maui. Additionally, we describe the adult female and second- and third-instar female nymphs of a new gall-inducing Phyllococcus species, Ph. cryptocaryae Percy, Watson & Hodgson, sp. n., found in galls on the leaves of Cryptocarya mannii (Lauraceae) in the central Waianae Mountains on Oahu. Also found galling the same host plant, and often in close proximity on the same leaf, were immatures of the triozid psyllid, Paurotriozana adaptata Caldwell, 1940 (Hemiptera: Psylloidea: Triozidae). Both the new mealybug and the triozid psyllid appear to be geographically restricted to the only remaining tree of C. mannii on Oahu and are therefore extremely vulnerable to extinction.

Improved Waterlogging Tolerance in Roots of Cucumber Plants after Inoculation with Arbuscular Mycorrhizal Fungi

Mycorrhizal symbiosis enhances host plant resistance to various unfavorable environmental stresses, but whether and how it also enhances waterlogging tolerance in cucumber plants is not known. The objective of this study was to analyze the effect of Paraglomus occultum inoculation on biomass production, osmolyte levels, and the expression of 12 heat shock protein 70 (Hsp70) genes and 14 plasma membrane intrinsic protein (PIP) genes in the roots of cucumber plants under a short-term waterlogging stress (WS) (5 days) condition. Although the short-term WS treatment significantly inhibited the arbuscular mycorrhizal fungal colonization of roots, the inoculation with arbuscular mycorrhizal fungi (AMFs) significantly increased leaf, stem, and root biomass under WS. AMF inoculation also significantly increased root glucose, sucrose, betaine, and proline contents, along with decreased fructose levels, compared with the uninoculated control. More CsHsp70 and CsPIP genes were up-regulated in AMF-inoculated plants than in AMF-uninoculated plants in response to WS. AMF inoculation showed no significant effect on the expression of any of the examined CsHsp70 genes under no-waterlogging stress, but it did raise the expression of 11 of 12 CsHsp70 genes under WS. AMF colonization also down-regulated or had no effect on CsPIP expression under no-waterlogging stress, whereas it up-regulated the expression of 12 of the 14 CsPIP genes under WS. It is concluded that AMF inoculation enhances waterlogging tolerance in cucumber plants by increasing osmolyte levels and stress-responsive gene (CsPIP and CsHsp70) expression.

Computational analysis of 16D10 effector peptides from root-knot nematodes and their interaction with Mi resistance (R) protein through molecular docking

Plant-parasitic nematodes, especially root-knot nematodes (RKNs), pose significant threats to global agriculture, affecting both the quantity and quality of crop yields. Central to the parasitism strategy of RKNs is the deployment of effector proteins, such as the 16D10 peptide, which interact with host plant resistance mechanisms. This study focuses on the computational analysis and molecular docking of 16D10 effector peptides derived from major RKN species (M. incognita, M. arenaria, M. hapla, M. javanica, and M. chitwoodi) to explore their interaction with the Mi resistance protein in tomatoes. Initial bioinformatics assessments included sequence retrieval, multiple sequence alignment, and phylogenetic analysis, utilizing tools such as CLUSTALW and the MEME Suite. Notably, our phylogenetic analysis revealed a close evolutionary relationship between M. incognita and M. chitwoodi, contrasting with other RKN species based on both DNA and protein data. Subsequent, in silico 3D modeling and docking studies, conducted using Chem-Sketch and MOE software, provided insights into the structural basis of the interaction between 16D10 peptides and the Mi protein. Our findings indicate that these interactions could play a crucial role in the modulation of plant defense mechanisms, potentially leading to effector-triggered susceptibility (ETS). This study not only enhances our understanding of nematode-host interactions but also aids in the development of novel strategies for managing RKN infections in economically important crops.

Characterization of arbuscular mycorrhizal fungal species associating with Zea mays.

Taxonomic identification of arbuscular mycorrhizal (AM) fungal spores extracted directly from the field is sometimes difficult because spores are often degraded or parasitized by other organisms. Single-spore inoculation of a suitable host plant allows for establishing monosporic cultures of AM fungi. This study aimed to propagate AM fungal spores isolated from maize soil using single spores for morphological characterization. First, trap cultures were established to trigger the sporulation of AM fungal species. Second, trap cultures were established with individual morphotypes by picking up only one spore under a dissecting microscope and transferring it to a small triangle of sterilized filter paper, which was then carefully inoculated below a root from germinated sorghum seeds in each pot and covered with a sterile substrate. All pots were placed in sunbags and maintained in a plant growth room for 120 days. Spores obtained from single spore trap cultures from each treatment, maize after oats (MO), maize after maize (MM), maize after peas (MP), and maize after soybean (MS), were extracted using the sieving method. Healthy spores were selected for morphological analysis. Direct PCR was conducted by crushing spores in RNAlater and applying three sets of primer pairs: ITS1 × ITS4, NS31 × AML2, and SSUmcf and LSUmBr. Nucleotide sequences obtained from Sanger sequencing were aligned on MEGA X. The phylogenetic tree showed that the closest neighbors of the propagated AM fungal species belonged to the genera Claroideoglomus, Funneliformis, Gigaspora, Paraglomus, and Rhizophagus. The morphological characteristics were compared to the descriptive features of described species posted on the INVAM website, and they included Acaulospora cavernata, Diversispora spurca, Funneliformis geosporus, Funneliformis mosseae, Gigaspora clarus, Gigaspora margarita, Glomus macrosporum, Paraglomus occultum, and Rhizophagus intraradices. These findings can provide a great contribution to crop productivity and sustainable management of the agricultural ecosystem. Also, the isolate analyzed could be grouped into efficient promoters of growth and mycorrhization of maize independent of their geographical location.

A novel virulence gene, cviA1 of Clavibacter michiganensis for necrosis development in the Nicotiana benthamiana plant

Clavibacter michiganensis is a Gram-positive bacterium that causes diverse disease symptoms in tomatoes and Nicotiana benthamiana, a surrogate host plant, including canker, blister lesions, and wilting. Previously, we reported that C. michiganensis also causes necrosis in N. benthamiana leaves. Here, to identify novel virulence genes of C. michiganensis required for necrosis development in N. benthamiana leaves, we screened 1,862 transposon-inserted mutants and identified a mutant strain that exhibited weak and delayed necrosis, whereas there was no discernible difference in blister lesions, canker, or wilting symptoms. Notably, this mutant caused canker similar to that of the wild-type strain, but caused mild wilting in tomato. This mutant carried a transposon in a chromosomal gene, called Clavibactervirulence gene A1 (cviA1). CviA1 encodes a 180-amino acid protein with a signal peptide (SP) at the N-terminus and two putative transmembrane domains (TMs) at the C-terminus. Interestingly, deletion of the SP or the C-terminus, including the two putative TMs, in CviA1 failed to restore full necrosis in the mutant, highlighting the importance of protein secretion and the putative TMs for necrosis. A paralog of cviA1, cviA2 is located on the large plasmid pCM2 of C. michiganensis. Despite its high similarity to cviA1, the introduction of cviA2 into the cviA1 mutant strain did not restore virulence. Similarly, the introduction of cviA1 into the Clavibacter capsici type strain PF008, which initially lacks cviA1, did not enhance necrosis symptoms. These results reveals that the chromosomal cviA1 gene in C. michiganensis plays an important role in necrosis development in N. benthamiana leaves.

Southern blight of water lily: The first host record of Agroathelia rolfsii on Nelumbo nucifera discovered in Florida, USA.

Nelumbo nucifera Gaertn. (Nelumbonaceae, Eudicots), also known as water lily or sacred lotus, is a nonnative and invasive plant commonly found in artificial ponds and natural lakes throughout Florida (UF-IFAS 2023; Wunderlin et al. 2023). In August 2020, a single sample of water lily plants showing large leaf spots were collected at a residence in Dunnellon, Marion County, Florida (80% disease prevalence with 40% leaf coverage). Symptoms and signs of the disease were necrotized adaxial leaf spots only, bordered by whitish mycelia and hyphae with clamp connections, and whitish to light brown sclerotia formed in the center (<0.7 mm diameter). Symptomatic tissue was plated on acid potato dextrose agar (APDA) amended with chloramphenicol (100 mg/L) and ampicillin (30mg/L), and incubated at 20 °C for one week. Data supporting the molecular identification of this putative pathogen were gathered by PCR amplification and Sanger sequencing of the complete internal transcribed spacer (ITS) and a fragment of the large subunit (LSU) of the rRNA gene (~1.5 kb) using primers ITS1F and LR5 (FDACS-DPI PPST 2020-105211, GenBank OR492009) (White et al. 1990). The identification of the host was confirmed by Sanger sequencing of three plant barcode fragments: ITS2 (ITS2-S2F/ITS4, OR492008), ribulose 1,5-bisphosphate carboxylase/oxygenase large subunit (rbcL) (rbcLa-F/rbcLa-R, GenBank OR502388), and Maturase K (matK) (matK-KIM1R/matK-KIM3F, GenBank OR502389) (Fazekas et al. 2012). MegaBLAST queries of the ITS/LSU sequence obtained here recovered a 99.61% match to the fungal pathogen Agroathelia (=Athelia) rolfsii (Sacc.) Redhead & Mullineux. (Redhead and Mullineux 2023) (Amylocorticiaceae, Agaricomycotina) strain GP3 (GenBank JABRWF010000005) (Yan et al. 2021). MegaBLAST queries of three host plant DNA barcodes recovered matches of greater than 99.62% similarity to N. nucifera sequences. After diagnosis, symptomatic dried leaf samples were deposited at Plant Industry Herbarium Gainesville (PIHG 17807) and an axenic culture was deposited at the Agricultural Research Services Culture Collection (NRRL 66964). Koch's postulates were fulfilled by the inoculation of sclerotia (as in Terrones-Salgado et al. 2022) on adaxial leaf surface of four-week- old water lily transplants obtained from an artificial pond on campus (two plants with five leaves each). One additional transplant was not inoculated and served as a control; this plant remained asymptomatic during the experimentation period. Each transplant was kept in a 27-gallon plastic container (21W × 30L × 14H in) filled with tap water containing one tablespoon of 20-20-20 all-purpose-water-soluble plant fertilizer (VPG, TX, USA) in a plant biosafety level 2 greenhouse (23 °C, >50% relative humidity, and a 12-h/12-h photoperiod). All inoculated leaves showed necrotized areas after one week and new sclerotia were observed floating on the water surface after three weeks. Fungal pathogen was reisolated and reidentified subsequently. Agroathelia rolfsii is the causal agent of southern blight, also known as grey rot, and is reported from at least in 260 plant genera, including specialty crops such as citrus, cucumber, pepper, peanuts, pumpkin, and strawberry (Farr and Rossman 2018). Agroathelia rolfsii usually causes lower stem, crown, and root rots; consequently, leaf spots are a noteworthy presentation of symptoms for this fungus.

Serine proteinase inhibitors from Nicotiana benthamiana, a nonpreferred host plant, inhibit the growth of Myzus persicae (green peach aphid).

The green peach aphid (Myzus persicae) is a severe agricultural crop pest that has developed resistance to most current control methods, requiring the urgent development of novel strategies. Plant proteinase inhibitors (PINs) are small proteins that protect plants against pathogens and/or herbivores, likely by preventing efficient protein digestion. We identified 67 protease genes in the transcriptomes of three M. persicae lineages (USDA-Red, G002 and G006). Comparison of gene expression levels in aphid guts and whole aphids showed that several proteases, including a highly expressed serine protease, are significantly overexpressed in the guts. Furthermore, we identified three genes encoding serine protease inhibitors (SerPIN-II1, 2 and 3) in Nicotiana benthamiana, which is a nonpreferred host for M. persicae. Using virus-induced gene silencing (VIGS) with a tobacco rattle virus (TRV) vector and overexpression with a turnip mosaic virus (TuMV) vector, we demonstrated that N. benthamiana SerPIN-II1 and SerPIN-II2 cause reduced survival and growth, but do not affect aphid protein content. Likewise, SerPIN-II3 overexpression reduced survival and growth, and serpin-II3 knockout mutations, which we generated using CRISPR/Cas9, increased survival and growth. Protein content was significantly increased in aphids fed on SerPIN-II3 overexpressing plants, yet it was decreased in aphids fed on serpin-II3 mutants. Our results show that three PIN-IIs from N. benthamiana, a nonpreferred host plant, effectively inhibit M. persicae survival and growth, thereby representing a new resource for the development of aphid-resistant crop plants. © 2024 Society of Chemical Industry.

Ontogeny and phylogeny of the genus Solus Watson, 1913 (Lepidoptera: Saturniidae)

Abstract Preimaginal stages of the enigmatic genus Solus Watson, 1913 are described for the first time, based on a completed life history of a representative species Solus parvifenestratus Bryk, 1944 fed with Camphora officinarum, with a report on testing of alternative potential host plants. The complete mitochondrial genomes are produced for two species within the genus and they are used to construct phylogenetic hypothesis and analyze nucleotide diversity. The alternative hypotheses derived from the molecular analyses are discussed in light of 14 morphological and biological features, the optimal result supports Solus to be the sister group of Saturniini + Attacini and justifies the establishment of the tribe Solini within the subfamily Saturniinae.

Candidate membrane protein gene families related to chemoreception in a wood-boring beetle, Pharsalia antennata Gahan (Coleoptera: Cerambycidae)

The longhorned beetles are key players for the maintenance of biodiversity in the terrestrial ecosystem. As xylophagous cerambycid insects in Coleoptera, the beetles have evolved specialized olfactory and gustatory systems to recognize chemical cues in the surrounding habitats. Despite over 36,000 described species in the Cerambycidae family including a wood-boring pest Pharsalia antennata, only a limited number of them (<1 %) have been characterized regarding their chemical ecology at the molecular level. Here, we surveyed four membrane protein gene families in P. antennata related to chemoreception through transcriptomics, phylogenetics and expression profiling analyses. In total, 144 genes encoding 72 odorant receptors (ORs), 33 gustatory receptors (GRs), 23 ionotropic receptors (IRs), four sensory neuron membrane proteins (SNMPs) and 12 ionotropic glutamate receptors (iGluRs) were harvested from the transcriptome of multiple tissues including antennae and legs of both sexes. The lineage-specific expansion of PantORs possibly implied a diverse range of host plants in this beetle, supporting this correlation between the host range and olfactory receptor repertoire sizes across cerambycid species. Further phylogenetic analysis revealed that Group 2 was contributed mainly to the large OR gene repertoire in P. antennata, representing 18 genes in Group 2A and eight in Group 2B. On the other hand, some key chemosensory genes were identified by applying a phylogenetics approach, such as PantOR21 close to the 2-phenylethanol receptor in Megacyllene caryae, three carbon dioxide GRs and seven Antennal IRs (A-IRs) clades. We also determined sex- and tissue-specific expression profiles of 69 chemosensory genes, revealing the high expression of most PantORs in antennae. Noticeably, 10 sex-biased genes (six PantORs, three PantIRs and PantSNMP1a) were presented in antennae, five sex-biased PantGRs in legs and 39 sex-biased genes (15 PantORs, 13 PantGRs, eight PantIRs and three PantSNMPs) in abdomens. These findings have greatly enhanced our knowledge about the chemical ecology of P. antennata and identify candidate molecular targets for mediating smell and taste of this beetle.