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Biotic disturbances caused by insects and pathogens have a major impact on forests in the Northern Hemisphere. Knowledge of the effects of increasing temperature on the performance of these forest pests will thus be crucial for predicting future disturbance risks. Here, we systematically review the direct effects of increasing temperatures on four functional subgroups of forest pests, including leaf chewers, sap suckers, bark and wood borers, and pathogens. We considered 118 studies (2003–2022) representing 72 pest species feeding on 33 host genera from sub‐tropical, temperate and boreal forests in Asia, Europe and North America. Based on a subset of 89 studies reporting the required data, we conducted a meta‐analysis 1) distinguishing the functional subgroups, and 2) considering the main life‐history traits, i.e. development, fitness and survival. A temperature corresponding to the expected mean temperature during the growing season in the years 2081–2100 had a significant positive effect on the overall performance of leaf chewers (+18%) and bark and wood borers (+10%), while sap suckers and pathogens remained unaffected. In contrast, performance was not or even significantly negatively affected when a more pronounced temperature increase, i.e. corresponding to the temperature maxima in 2081–2100, was considered. This finding reflects the non‐linear temperature–performance relationship beyond currently evolved temperature optima in insects and pathogens. Furthermore, we showed that differential responses of life‐history traits to increased temperatures may counterbalance each other (e.g. development versus survival), highlighting the importance of a multi‐trait approach to assessing the impact of global warming on pest performance. By quantifying the effects of increasing temperatures on forest pest performance, our results facilitate the prediction of biotic disturbance impacts in a future climate. For instance, they could provide a valuable contribution to the parameterization of large‐scale ecosystem models, which often do not explicitly consider the response of biotic disturbances to climate change. [ABSTRACT FROM AUTHOR]

The first step in trait introgression is to identify and assess novel sources of variation. For shrub willow (Salix) breeders, there is an abundance of understudied species within a genus that readily hybridizes. Breeding targets in shrub willow center on traits contributing to biomass yield for bioenergy. These include stem biomass, insect and pathogen resistance, and leaf architecture traits. More specifically, breeding for durable resistance to willow leaf rust (Melampsora spp.) is of particular importance as the pathogen can significantly reduce biomass yields in commercial production. The Salix F1 hybrid common parent population (Salix F1 HCP) was created to characterize the variation among eight species‐hybrid families and map QTL for targeted traits. A female and male S. purpurea were used as common parents in crosses made to male S. suchowensis, S. viminalis, S. koriyanagi, and S. udensis and female S. viminalis, S. integra, S. suchowensis to produce eight families that were planted in field trials at Cornell AgriTech in Geneva, NY and phenotyped. Using 16 previously described parental backcross linkage maps and two newly generated S. purpurea consensus maps, we identified 215 QTL across all eight families and in every parent. These included 15 leaf rust severity, 61 herbivory, 65 leaf architecture, and 74 yield component QTL, resulting in 50 unique overlapping regions within the population. These genetic loci serve as an important foundation for future shrub willow breeding, and each interspecific family was identified as a novel source of useful alleles for trait introgression into high yielding cultivars. [ABSTRACT FROM AUTHOR]

Despite major breeding efforts by various national and international agencies, yields for the ~40 million hectares of maize, the major food crop in sub‐Saharan Africa, have stagnated at <2 tons/ha/year for the past decade, one‐third the global average. Breeders have succeeded in breeding increased yield with a modicum of tolerance to some single‐weed or pathogen stresses. There has been minimal adoption of these varieties because introgressing polygenic yield and tolerance traits into locally adapted material is very challenging. Multiple traits to deal with pests (weeds, pathogens, and insects) are needed for farmer acceptance, because African fields typically encounter multiple pest constraints. Also, maize has no inherent resistance to some of these pest constraints, rendering them intractable to traditional breeding. The proposed solution is to simultaneously engineer multiple traits into one genetic locus. The dominantly inherited multi‐pest resistance trait single locus can be bred simply into locally adapted, elite high‐yielding material, and would be valuable for farmers, vastly increasing maize yields, and allowing for more than regional maize sufficiency. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

BACKGROUND: β‐N‐acetylhexosaminidases (HEXs) are widely distributed in fungi and involved in cell wall chitin metabolism and utilization of chitin‐containing substrates. However, details of the fungal pathogens‐derived HEXs in the interaction with their hosts remain limited. RESULTS: An insect nutrients‐induced β‐N‐acetylhexosaminidase, BbHex1, was identified from the entomopathogenic fungus Beauveria bassiana, which was involved in cell wall modification and degradation of insect cuticle. BbHex1 was localized to cell wall and secreted, and displayed enzyme activity to degrade the chitinase‐hydrolyzed product (GlcNAc)2. Disruption of BbHex1 resulted in a significant decrease in the level of cell wall chitin in the presence of insect nutrients and during infection of insects, with impaired ability to penetrate insect cuticle, accompanying downregulated cell wall metabolism‐involved and cuticle‐degrading chitinase genes. However, the opposite phenotypes were examined in the gene overexpression strain. Distinctly altered cell wall structures caused by BbHex1 mutation and overexpression led to the easy activation and evasion (respectively) of insect immune response during fungal infection. As a result, BbHex1 contributed to fungal virulence. Bioinformatics analysis revealed that promoters of some co‐expressed chitinase genes with the BbHex1 promoter shared conserved transcription factors Skn7, Msn2 and Ste12, and CreA‐binding motifs, implying co‐regulation of those genes with BbHex1. CONCLUSION: These data support a mechanism that the fungal pathogen specifically expresses BbHex1, which is co‐expressed with chitinases to modify cell wall for evasion of insect immune recognition and to degrade insect cuticle, and contributes to the fungal virulence against insects. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The stable fly, Stomoxys calcitrans L. (Diptera: Muscidae), is a significant insect pest with global veterinary implications due to its capacity to both cause nuisance and transmit disease‐causing pathogens to livestock. This study aimed to determine the livestock bedding preferred for use as a development substrate by S. calcitrans larvae and field‐collected adults. The result showed that S. calcitrans larvae exhibited a preference (26.7%) for 7‐day‐old cow manure. Gravid females displayed a pronounced preference (55.0%) for fresh cow manure. As there were eight choices, indifference would result in 12.5% for each bedding substrate. Furthermore, the efficacy of four entomopathogenic nematodes (EPNs), namely Heterorhabditis bacteriophora (Poinar), Heterorhabditis indica Poinar, Karunakar & David (Rhabditida: Heterorhabditidae), Steinernema siamkayai Poinar, Karunakar & David and Steinernema carpocapsae (Weiser) (Rhabditida: Steinernematidae), against S. calcitrans larvae and the persistence after application to livestock bedding substrates were evaluated under laboratory conditions. In filter paper bioassays, all four EPNs caused 76.7%–100.0% mortality in the second instar larvae of S. calcitrans when applied at 50 and 100 infective juveniles (IJs)/cm2 within 5 days after exposure. For the third instar larvae of S. calcitrans, only H. indica induced high mortalities of 86.6% when applied at 100 IJs/cm2 within 5 days after exposure, while the other EPNs resulted in mortalities of less than 70%. The data further demonstrated that H. bacteriophora, H. indica and S. siamkayai remained present in the substrates linked to S. calcitrans larvae for as long as 7 days after the application of EPNs. This study demonstrates the potential of EPNs as a biologically based control agent against larvae of S. calcitrans, a serious pest and significant vector for various livestock animals. [ABSTRACT FROM AUTHOR]

Plants have evolved diverse defense mechanisms encompassing physical and chemical barriers. Cotton pigment glands are known for containing various defense metabolites, but the precise regulation of gland size to modulate defense compound levels remains enigmatic. Here, it is discovered that the VQ domain‐containing protein JAVL negatively regulates pigment gland size and the biosynthesis of defense compounds, while the MYC2‐like transcription factor GoPGF has the opposite effect. Notably, GoPGF directly activates the expression of JAVL, whereas JAVL suppresses GoPGF transcription, establishing a negative feedback loop that maintains the expression homeostasis between GoPGF and JAVL. Furthermore, it is observed that JAVL negatively regulates jasmonate levels by inhibiting the expression of jasmonate biosynthetic genes and interacting with GoPGF to attenuate its activation effects, thereby maintaining homeostatic regulation of jasmonate levels. The increased expression ratio of GoPGF to JAVL leads to enlarged pigment glands and elevated jasmonates and defense compounds, enhancing insect and pathogen resistance in cotton. These findings unveil a new mechanism for regulating gland size and secondary metabolites biosynthesis, providing innovative strategies for strengthening plant defense. [ABSTRACT FROM AUTHOR]

BACKGROUND: Citrus huanglongbing (HLB) is a devastating disease caused by Candidatus Liberibacter asiaticus (CLas) that affects the citrus industry. In nature, CLas relies primarily on Diaphorina citri Kuwayama as its vector for dissemination. After D. citri ingests CLas‐infected citrus, the pathogen infiltrates the insect's body, where it thrives, reproduces, and exerts regulatory control over the growth and metabolism of D. citri. Previous studies have shown that CLas alters the composition of proteins in the saliva of D. citri, but the functions of these proteins remain largely unknown. RESULTS: In this study, we detected two proteins (DcitSGP1 and DcitSGP3) with high expression levels in CLas‐infected D. citri. Quantitative PCR and Western blotting analysis showed that the two proteins were highly expressed in the salivary glands and delivered into the host plant during feeding. Silencing the two genes significantly decreased the survival rate for D. citri, reduced phloem nutrition sucking and promoted jasmonic acid (JA) defenses in citrus. By contrast, after overexpressing the two genes in citrus, the expression levels of JA pathway‐associated genes decreased. CONCLUSION: Our results suggest that CLas can indirectly suppress the defenses of citrus and support feeding by D. citri via increasing the levels of effectors in the insect's saliva. This discovery facilitates further research into the interaction between insect vectors and pathogens. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Summary: Maize is one of the most important crops for food, cattle feed and energy production. However, maize is frequently attacked by various pathogens and pests, which pose a significant threat to maize yield and quality. Identification of quantitative trait loci and genes for resistance to pests will provide the basis for resistance breeding in maize. Here, a β‐glucosidase ZmBGLU17 was identified as a resistance gene against Pythium aphanidermatum, one of the causal agents of corn stalk rot, by genome‐wide association analysis. Genetic analysis showed that both structural variations at the promoter and a single nucleotide polymorphism at the fifth intron distinguish the two ZmBGLU17 alleles. The causative polymorphism near the GT‐AG splice site activates cryptic alternative splicing and intron retention of ZmBGLU17 mRNA, leading to the downregulation of functional ZmBGLU17 transcripts. ZmBGLU17 localizes in both the extracellular matrix and vacuole and contribute to the accumulation of two defence metabolites lignin and DIMBOA. Silencing of ZmBGLU17 reduces maize resistance against P. aphanidermatum, while overexpression significantly enhances resistance of maize against both the oomycete pathogen P. aphanidermatum and the Asian corn borer Ostrinia furnacalis. Notably, ZmBGLU17 overexpression lines exhibited normal growth and yield phenotype in the field. Taken together, our findings reveal that the apoplastic and vacuolar localized ZmBGLU17 confers resistance to both pathogens and insect pests in maize without a yield penalty, by fine‐tuning the accumulation of lignin and DIMBOA. [ABSTRACT FROM AUTHOR]

Pathogens play a key role in insect population dynamics, contributing to short‐term fluctuations in abundance as well as long‐term demographic trends. Two key factors that influence the effects of entomopathogens on herbivorous insect populations are modes of pathogen transmission and larval host plants. In this study, we examined tritrophic interactions between a sequestering specialist lepidopteran, Euphydryas phaeton, and a viral pathogen, Junonia coenia densovirus, on its native host plant, Chelone glabra, and a novel host plant, Plantago lanceolata, to explore whether host plant mediates viral transmission, survival, and viral loads. A two‐factor factorial experiment was conducted in the laboratory with natal larval clusters randomly assigned to either the native or novel host plant and crossed with either uninoculated controls or viral inoculation (20% of individuals in the cluster inoculated). Diapausing clusters were overwintered in the laboratory and checked weekly for mortality. At the end of diapause, all surviving individuals were reared to adulthood to estimate survivorship. All individuals were screened to quantify viral loads, and estimate horizontal transmission postmortem. To test for vertical transmission, adults were mated, and the progeny were screened for viral presence. Within virus‐treated groups, we found evidence for both horizontal and vertical transmission. Larval clusters reared on the native host plant had slightly higher horizontal transmission. Survival probability was lower in clusters feeding on the native host plant, with inoculated groups reared on the native host plant experiencing complete mortality. Viral loads did not differ by the host plant, although viral loads decreased with increased sequestration of secondary compounds on both host plants. Our results indicate that the use of a novel host plant may confer fitness benefits in terms of survival and reduced viral transmission when larvae feeding on it are infected with this pathogen, supporting hypotheses of potential evolutionary advantages of a host range expansion in the context of tritrophic interactions. [ABSTRACT FROM AUTHOR]

We report observations of Onnia subtriquetra on bishop pine (Pinus muricata) and shore pine (Pinus contorta var. contorta) from north coastal California. Our identification of this fungus is supported by molecular information, morphological characteristics, and and a description of the observed range of the fungus on the West Coast. These observations represent an expansion of the geographic and host ranges of Onnia subtriquetra, which on the observed sites is generally associated with declining tree condition and the presence of other native forest pathogens and insects. [ABSTRACT FROM AUTHOR]

Plant enemies can indirectly affect pollinators by modifying plant traits, but simultaneous tests of herbivore and pathogen effects are lacking, and the role of floral volatiles has seldom been assessed.In this study, we tested for indirect effects of insect herbivores and pathogens on pollinator attraction via altered floral volatile emissions, and its consequences for plant fitness in Brassica rapa. Plants in the field were exposed to either no damage or damage by caterpillars (Mamestra brassicae), aphids (Brevicoryne brassicae), a leaf fungus (Sclerotinia sclerotiorum), or a bacterium (Xanthomonas campestris pv. campestris). We then recorded pollinator visits and measured floral traits (flower number, volatiles) and plant fitness‐correlates. We additionally performed a greenhouse experiment with artificial floral emitters to test for effects of target volatiles on pollinator attraction.In the field experiments, relative to controls, plants subjected to herbivory by the aphid B. brassicae (but not those exposed to the other enemies) exhibited a marked reduction in the emission of two volatile organic compounds (nonanal and 2‐butyl‐1‐octanol), experienced lower pollinator visits and produced seeds of lower quality in terms of seed biomass and germination rate, while flower output itself was not affected. Consistently, artificial emitters with reduced amounts of these volatile organic compounds were less attractive to pollinators under greenhouse conditions.Synthesis. These results provide strong evidence for volatile‐mediated indirect interactions between plant enemies and pollinators ultimately impacting plant fitness, and further point at enemy and compound specificity in such effects. [ABSTRACT FROM AUTHOR]

Microbial biopesticides to control plant pathogens and insects in crops have had significant success. However, there have been relatively few successes for microbial bioherbicides in crops, despite considerable numbers of publications and commercial product introductions in this area. Marketed microbial bioherbicide products for use in agriculture have been largely unsuccessful. This article covers the potential advantages of successful microbial bioherbicides, as well as the biological and technical issues that have limited their success. Technologies to overcome the problems that have limited the success of these products are discussed. The many advantages of using killed microbial products (e.g. cell‐free filtrates) over living microbial products as bioherbicides are detailed. A commercialized mycoherbicide that has been selected for in the laboratory for control of the parasitic weed Striga hermonthica is being used with some success in Africa, indicating that non‐transgenic modification of the genetics of bioherbicide microbes for improved efficacy is acceptable to some regulatory authorities. Genetic modifications to improve efficacy and host range, as well as improved application technology to greatly reduce the amount of product needed are two technologies that are likely to expand the use of microbial bioherbicides in the future. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The North has experienced unprecedented rates of warming over the past few decades, impacting the survival and development of insects and the pathogens that they carry. Since 2019, Arctic foxes from Canada (Nunavut) have been observed with fur loss inconsistent with natural shedding of fur. Adult lice were collected from Arctic foxes from Nunavut (n = 1) and Svalbard (n = 2; Norway) and were identified as sucking lice (suborder Anoplura). Using conventional PCR targeting the mitochondrial cytochrome c oxidase subunit 1 gene (cox1), lice from Canada and Svalbard were 100% similar (8 pooled samples from Nunavut and 3 pooled samples from Svalbard), indicating that there is potential gene flow between ectoparasites on Scandinavian and North American Arctic fox populations. The cox1 sequences of Arctic fox lice and dog sucking lice (Linognathus setosus) had significant differences (87% identity), suggesting that foxes may harbour a cryptic species that has not previously been recognised. Conventional PCR targeting the gltA gene for Bartonella bacteria amplified DNA from an unknown gammaproteobacteria from two pooled louse samples collected from Svalbard foxes. The amplified sequences were 100% identical to each other but were only 78% like Proteus mirabilis reported in GenBank (CP053614), suggesting that lice on Arctic foxes may carry unique microorganisms that have yet to be described. [ABSTRACT FROM AUTHOR]

The Janzen–Connell hypothesis (JCH) predicts that attack by specialist enemies on seedlings increases with conspecific seedling density, but studies have rarely experimentally tested for the contingency of such effects on the tree community context (e.g. diversity, composition) ormeasured responses by different enemies (e.g. herbivores, pathogens). We conducted a field study in a large‐scale system evaluating tree species diversity and conspecific density effects on leaf damage on mahogany Swietenia macrophylla seedlings. We established quadrats of eight levels of seedling density across mahogany tree monocultures and tree species polycultures including mahogany, and recorded percent leaf damage by insects and percent leaf necrosis by a pathogenic fungus on mahogany seedlings. We found contrasting effects of tree species diversity on insects and pathogens. Whereas tree diversity did not affect leaf damage by insects, it had a significant negative effect on leaf necrosis by pathogens whereby, on average, percent leaf necrosis on mahogany seedlings in polyculture was half of that observed in monoculture. We discuss the potential influences of changes in mahogany tree density versus frequency (relative to other tree species) driving this diversity effect. Unexpectedly, we found no effect of seedling conspecific density on either leaf insect or pathogen damage (i.e. density‐independent attack). Likewise, we found no significant tree diversity by seedling density interaction, indicating that plant enemies were consistently unresponsive to variation in seedling density acrosslevels of tree diversity. Overall, this study provides a unique test of the JCH by experimentally evaluating seedling density and tree diversity effects on contrasting plant enemies and, in turn, the controls they exert over plant recruitment. [ABSTRACT FROM AUTHOR]

BACKGROUND: Two consecutive field trials using a blend of entomopathogens in combination with a new chemistry insecticide were conducted to determine treatment effects on onion thrips (Thrips tabaci Lindeman) populations, crop damage, plant development, crop yield and impact on natural enemies. Products were tested in an onion cropping system and included the insect pathogenic fungus Beauveria bassiana (isolate WG‐11), an entomopathogenic nematode Heterorhabditis bacteriophora (strain VS) and the new‐chemistry chemical insecticide spinetoram. RESULTS: In all treatments, a significant decrease in thrips per plant population was detected in both trials. Overall, dual application of entomopathogens and insecticide was more effective than singly applied treatments. The lowest number of thrips larvae (1.96 and 3.85) and adults (0.00 and 0.00) were recorded when treated with dual application of B. bassiana and spinetoram at 7 days post application (DPA) after the second spray application in 2017and 2018, respectively. Damage on onion plants was considerably decreased in all treatments relative to the control. The lowest damage was observed on onion plants treated with B. bassiana + spinetoram at 7 DPA after the second spray application during both years. A significant decrease in the number of natural enemies (beetles, spiders, mites, lacewings, ants and bugs) on onion plants was recorded during both years. Insect pathogens when applied alone and in combination with each other considerably protected arthropod natural enemies compared to insecticide application applied alone. Significant increase in plant agronomic traits was observed compared to the control. Among all the treatments, B. bassiana + spinetoram produced maximum leaf length, leaf weight, total leaves, neck diameter, bulb diameter, number of rings per bulb, bulb weight, dry matter and plant yield following the 2017and 2018 applications, respectively. CONCLUSION: The findings of the study reveal the potential of using insect pathogens and insecticide for control of T. tabaci. However, combinations containing spinetoram are harmful to nontarget organisms, whereas biological control agents help in protecting biodiversity in onion agroecosystems. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

SUMMARY: The oxylipin plant hormone (3R,7S)‐jasmonoyl‐l‐isoleucine [or (+)‐7‐iso‐jasmonoyl‐l‐isoleucine, JA‐Ile] is widely recognized as a plant defense hormone against pathogens and chewing insects. The metabolism of JA‐Ile into 12‐OH‐JA‐Ile and 12‐COOH‐JA‐Ile is the central mechanism for the inactivation of JA signaling. Recently, 12‐OH‐JA‐Ile was reported to function as a ligand for the JA‐Ile co‐receptor COI1‐JAZ. However, in previous studies, '12‐OH‐JA‐Ile' used was a mixture of four stereoisomers, the naturally occurring cis‐isomer (3R,7S)‐12‐OH‐JA‐Ile and the trans‐isomer (3R,7R)‐12‐OH‐JA‐Ile, and the unnatural cis‐isomer (3S,7R)‐12‐OH‐JA‐Ile and the trans‐isomer (3S,7S)‐12‐OH‐JA‐Ile. Thus, the genuine bioactive form of 12‐OH‐JA‐Ile has not yet been identified. In the present study, we prepared pure stereoisomers of 12‐OH‐JA‐Ile and identified (3R,7S)‐12‐OH‐JA‐Ile as the naturally occurring bioactive form of 12‐OH‐JA‐Ile and found that it binds to COI1‐JAZ9 as effectively as (3R,7S)‐JA‐Ile. In addition, we revealed that the unnatural trans‐isomer (3S,7S)‐12‐OH‐JA‐l‐Ile functions as another bioactive isomer. The pure (3R,7S)‐12‐OH‐JA‐Ile causes partial JA‐responsive gene expression without affecting the expression of JAZ8/10, which is involved in the negative feedback regulation of JA‐signaling. Thus, (3R,7S)‐12‐OH‐JA‐Ile could cause weak and sustainable expression of certain JA‐responsive genes until the catabolism of (3R,7S)‐12‐OH‐JA‐Ile into (3R,7S)‐12‐COOH‐JA‐Ile occurs. The use of chemically pure (3R,7S)‐12‐OH‐JA‐Ile confirmed the genuine biological activities of '12‐OH‐JA‐Ile' by excluding the possible effects of other stereoisomers. A chemical supply of pure (3R,7S)‐12‐OH‐JA‐Ile with an exact bioactivity profile will enable further detailed studies of the unique role of 12‐OH‐JA‐Ile in planta. Significance Statement: In the present study, we have demonstrated that (3R,7S)‐12‐OH‐JA‐Ile is the naturally occurring bioactive form of 12‐OH‐JA‐Ile and that it binds to COI1‐JAZ9 as effectively as (3R,7S)‐JA‐Ile. (3R,7S)‐12‐OH‐JA‐Ile causes partial JA‐responsive gene expression without affecting the expression of JAZ8/10, which is involved in the negative feedback regulation of JA‐signaling. [ABSTRACT FROM AUTHOR]

BACKGROUND: Homolog of the yeast Fus3/Kss1 mitogen‐activated protein kinase (MAPK) pathway and its target transcription factor, Ste12‐like, are involved in penetration of host cuticle/pathogenicity in many ascomycete pathogens. However, details of their interaction during fungal infection, as well as their controlled other virulence‐associated traits, are unclear. RESULTS: Ste12‐like (BbSte12) and Fus3/Kss1 MAPK homolog (Bbmpk1) interacted in nucleus, and phosphorylation of BbSte12 by Bbmpk1 was essential for penetration of insect cuticle in an insect fungal pathogen, Beauveria bassiana. However, some distinct biocontrol‐traits were found to be mediated by Ste12 and Bbmpk1. In contrast to ΔBbmpk1 colony that grew more rapid than wild‐type strain, inactivation of BbSte12 resulted in the opposite phenotype, which was consistent with their different proliferation rates in insect hemocoel after direct injection of conidia bypass the cuticle. Reduced conidial yield with decreased hydrophobicity was examined in both mutants, however they displayed distinct conidiogenesis, accompanying with differently altered cell cycle, distinct hyphal branching and septum formation. Moreover, ΔBbmpk1 showed increased tolerance to oxidative agent, whereas the opposite phenotype was seen for ΔBbSte12 strain. RNA sequencing analysis revealed that Bbmpk1 controlled 356 genes depending on BbSte12 during cuticle penetration, but 1077 and 584 genes were independently controlled by Bbmpk1 and BbSte12. CONCLUSION: BbSte12 and Bbmpk1 separately participate in additional pathways for control of conidiation, growth and hyphal differentiation, as well as oxidative stress response besides regulating cuticle penetration via phosphorylation cascade. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

According to the sixth assessment report of the Intergovernmental Panel on Climate Change (IPCC), global climate change is now unequivocal. Tunisia, like many other countries, has been affected by climate changes, including rising temperatures, intense heatwaves, and altered precipitation regimes. Tunisia's mean annual temperatures has risen about +1.4 °C in the twentieth century, with the most rapid warming taking place since the 1970s. Drought represents a primary contributing factor to tree decline and dieback. Long‐term drought can result in reduced growth and health of trees, thereby increasing their susceptibility to insect pests and pathogens. Reported increases in tree mortality point toward accelerating global forest vulnerability under hotter temperatures and longer, more intense droughts. In order to assess the effect of these climate changes on the current state of forest ecosystems in Tunisia and their evolution, an investigative study was required. Here, we review the current state of knowledge on the effects of climate change on sclerophyllous and semi‐deciduous forest ecosystems in Tunisia. Natural disturbance during recent years, as well as the adaptability and resilience of some forest species to climate change, were surveyed. The Standardized Precipitation Evapotranspiration Index (SPEI) is a multi‐scalar drought index based on climate data that has been used to analyse drought variability. The SPEI time scale analysis showed a negative trend over the 1955–2021 period in Tunisian forest regions. In 2021, Tunisia lost 280 km2 of tree cover to fires, which is equivalent to 26% of the total lost area between 2008 and 2021. Changing climate conditions have also affected phenological parameters, with an advance in the start of the green season (SOS) of 9.4 days, a delay at the end of the green season (EOS) of 5 days, with a consequent extended duration of the green season (LOS) by an average of 14.2 days. All of these alarming findings invite us to seek adaptation strategies for forest ecosystems. Adapting forests to climate change is therefore a challenge for scientists as well as policymakers and managers. [ABSTRACT FROM AUTHOR]

Terpenoids, one of the most important plant volatiles, mediate the communication between plants and pollinators, herbivores as well as pathogens. Recently, researchers have shown intensive interest in the complicated interactions. Linalool, an acyclic monoterpene, is one of the common flavor‐related volatiles across the plant kingdom. In this review, we summarized the biosynthesis and transcriptional regulation of terpenoids, and then focused on the biological function of linalool in plant–insect interactions. We found that flowers emitting linalool as the dominant volatile appeal to broad assemblages of pollinators, while some pollinators typically have strong preferences for these flowers as well. Hereinto, moths and bees are the main pollinators of linalool‐dominant flowers. Additionally, linalool produced by plants could defend against insect pests and pathogens. It is noteworthy that the two enantiomers of linalool have distinct functions. (S)‐(+)‐linalool mainly attracts pollinators, while (R)‐(−)‐linalool seems to act as insect repellents. Further research on the biofunctional diversity and genetic mechanisms of linalool enantiomers will reveal the complexity of plant survival strategies, and the increasing understanding of the molecular mechanisms underlying their biosynthesis and transcriptional regulation will provide theoretical foundation and practical basis for directional transformation of plants. [ABSTRACT FROM AUTHOR]

Summary: Apolygus lucorum (Meyer‐Dur; Heteroptera: Miridae) is a major agricultural pest infesting crops, vegetables, and fruit trees. During feeding, A. lucorum secretes a plethora of effectors into its hosts to promote infestation. However, the molecular mechanisms of these effectors manipulating plant immunity are largely unknown.Here, we investigated the molecular mechanism underlying the effector Al106 manipulation of plant–insect interaction by RNA interference, electrical penetration graph, insect and pathogen bioassays, protein–protein interaction studies, and protein ubiquitination experiment.Expression of Al106 in Nicotiana benthamiana inhibits pathogen‐associated molecular pattern‐induced cell death and reactive oxygen species burst, and promotes insect feeding and plant pathogen infection. In addition, peptidyl‐prolyl cis‐trans isomerase (PPIase) activity of Al106 is required for its function to inhibit PTI.Al106 interacts with a plant U‐box (PUB) protein, PUB33, from N. benthamiana and Arabidopsis thaliana. We also demonstrated that PUB33 is a positive regulator of plant immunity. Furthermore, an in vivo assay revealed that Al106 inhibits ubiquitination of NbPUB33 depending on PPIase activity.Our findings revealed that a novel cyclophilin effector may interact with plant PUB33 to suppress plant immunity and facilitate insect feeding in a PPIase activity‐dependent manner. [ABSTRACT FROM AUTHOR]

Passage experiments that sequentially infect hosts with parasites have long been used to manipulate virulence. However, for many invertebrate pathogens, passage has been applied naively without a full theoretical understanding of how best to select for increased virulence and this has led to very mixed results. Understanding the evolution of virulence is complex because selection on parasites occurs across multiple spatial scales with potentially different conflicts operating on parasites with different life histories. For example, in social microbes, strong selection on replication rate within hosts can lead to cheating and loss of virulence, because investment in public goods virulence reduces replication rate. In this study, we tested how varying mutation supply and selection for infectivity or pathogen yield (population size in hosts) affected the evolution of virulence against resistant hosts in the specialist insect pathogen Bacillus thuringiensis, aiming to optimize methods for strain improvement against a difficult to kill insect target. We show that selection for infectivity using competition between subpopulations in a metapopulation prevents social cheating, acts to retain key virulence plasmids, and facilitates increased virulence. Increased virulence was associated with reduced efficiency of sporulation, and possible loss of function in putative regulatory genes but not with altered expression of the primary virulence factors. Selection in a metapopulation provides a broadly applicable tool for improving the efficacy of biocontrol agents. Moreover, a structured host population can facilitate artificial selection on infectivity, while selection on life‐history traits such as faster replication or larger population sizes can reduce virulence in social microbes. [ABSTRACT FROM AUTHOR]

Plants interact with a large diversity of microbes and insects, both below and above ground. While studies have shown that belowground microbes affect the performance of plants and aboveground organisms, we lack insights into how belowground microbial communities may shape interactions between aboveground pathogens and insects. We investigated how soil microbiomes and aboveground organisms affect plant growth and development, and whether differences in soil microbiomes influence interactions between aboveground organisms. We conducted a growth‐chamber experiment with oak seedlings Quercus robur growing in three soils with similar abiotic soil properties but with distinct natural soil microbiomes. Seedlings were subjected to single or dual attack by powdery mildew Erysiphe alphitoides and aphids Tuberculatus annulatus, either in the presence or absence of prior attack by a free‐feeding caterpillar Phalera bucephala. Soil microbiomes were associated with differences in seedling height, and seedlings with multiple aboveground organisms had more but smaller leaves than healthy seedlings. The soil microbiome affected the severity of powdery mildew infection, and mediated the impact of co‐occurring aboveground organisms on aphid population size. Our study highlights that plant performance is affected by natural soil microbiomes as well as aboveground organisms, and that natural soil microbiomes can affect interactions between pathogens and insects. These findings are important to understand species interactions in natural systems, as well as for practical applications, such as manipulation of soil microbiomes to manage agricultural pests and diseases. [ABSTRACT FROM AUTHOR]

Non‐native pests in North America are a growing threat to native trees and forest communities. Theory suggests that a less specialised niche, as reflected by a pest's broad host range, may facilitate successful pest invasions. Incorporating a pest's host range characteristics along with life‐history traits may thus help us better predict future invasions and impacts.We quantified the host range of North American tree pests using indices of host taxonomic richness and the standard effect size of the mean pairwise distance between hosts, then compared the host ranges of non‐native and native pests. We next examined whether non‐native and native pests tended to be associated with phylogenetically distinct sets of host tree lineages. Finally, we evaluated whether pest impacts were associated with pest host ranges, nativity or pest type (i.e. insect vs. pathogen).We found that the set of tree hosts impacted by non‐native pests was phylogenetically distinct from hosts of native pests, and that non‐native insect pests had significantly broader host ranges than native insect pests, perhaps due to an innate ability to associate with diverse tree species. We also found that pathogens generally had broader host ranges than insect pests—possibly a result of more frequent host range expansion. While severity was not associated with pest nativity per se, non‐native pathogens had the greatest impact on their hosts across all pest subsets.Synthesis. We identified important differences in the host ranges of native and non‐native pests, with non‐native pests associated with a broader range of hosts, and this difference was most evident in comparisons between insect pests. We suggest a broad host range might facilitate non‐native pest establishment. We also highlight the need for further research on pest life histories and impacts to better understand the consequences of pest invasions. [ABSTRACT FROM AUTHOR]

Curated databases of species interactions are instrumental to exploring and understanding the spatial distribution of species and their biotic interactions. In the process of conducting such projects, data development and curation efforts may give rise to a data product with utility beyond the scope of the original work, but which becomes inaccessible over time. Data describing insect host–pathogen interactions are fairly rare, and should thus be preserved and curated with appropriate metadata. Here, we introduce the insectDisease R package, a mechanism for curating, updating and distributing data from the Ecological Database of the World's Insect Pathogens, a database of insect host–pathogen associations, including attempted inoculations and infection outcomes for insect hosts and pathogens (bacteria, fungi, nematodes, protozoans and viruses). This dataset has been utilized for several projects since its inception, but without a well‐defined, curated and permanent repository, its existence and access have been limited to word‐of‐mouth connections. The current effort presented here aims to provide a means to preserve, augment and disseminate the database in a documented and versioned format. This project is an example of the type of effort that will be necessary to maintain valuable databases after the original funding disappears. [ABSTRACT FROM AUTHOR]

BACKGROUND: Spodoptera frugiperda is one of the significant migratory pests in the Global Alert issued by the Food and Agriculture Organization of the United Nations. As an insect‐specific microbial insecticide, baculovirus has been used to control various pests. MicroRNA‐34‐5p (miR‐34‐5p) is involved in regulating growth, reproduction and innate immunity to pathogens in insects, playing an essential role in host–virus interactions. In this study, we explored the critical function of miR‐34‐5p encoded by S. frugiperda in the anti‐Autographa californica multiple nucleopolyhedrovirus (AcMNPV), providing a reference for the design of a miR‐34‐5p target biopesticide against S. frugiperda and a theoretical basis for the wide application of microRNAs (miRNAs) in green pest control technology. RESULTS: We focused on miR‐34‐5p identified as downregulated in Sf9 cells and S. frugiperda larvae infected by AcMNPV. The regulatory function of miR‐34‐5p in AcMNPV–S. frugiperda interactions was studied by transfecting synthetic mimics and inhibitors, and constructing recombinant bacmids with miR‐34‐5p overexpression. miR‐34‐5p inhibited the production of infectious budded virions at the cellular and insect levels, inhibited the replication of the viral DNA and glucose metabolism, and increased the transcription of the antimicrobial peptide gloverin. Furthermore, the virus genes odv‐e66, ac78 and ie2 were shown to be direct targets. CONCLUSION: We systematically revealed the mechanism by which miR‐34‐5p is involved in the insect antiviral process. miR‐34‐5p inhibited the replication and infection of AcMNPV by directly targeting AcMNPV genes, especially ac78 and ie2. Our study provides a new direction and thinking for the prevention and green control of lepidopteran pests. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Interspecific niche complementarity is a key mechanism posited to explain positive species richness–productivity relationships in plant communities. However, the exact nature of the niche dimensions that plant species partition remains poorly known.Species may partition abiotic resources that limit their growth, but species may also be specialized with respect to their set of biotic interactions with other trophic levels, in particular with enemies including pathogens and consumers. The lower host densities present in more species‐diverse plant communities may therefore result in smaller populations of specialized enemies, and in a smaller associated negative feedback these enemies exert on plant productivity.To test whether such host density‐dependent effects of enemies drive diversity–productivity relationships in young forest stands, we experimentally manipulated leaf fungal pathogens and insect herbivores in a large subtropical forest biodiversity–ecosystem functioning experiment in China (BEF‐China).We found that fungicide spraying of tree canopies removed the positive tree‐species richness–productivity relationship present in untreated control plots. The tree species that contributed the most to this effect were the ones with the highest fungicide‐induced growth increase in monoculture. Insecticide application did not cause comparable effects.Synthesis. Our findings suggest that tree species diversity may not only promote productivity by interspecific resource‐niche partitioning but also by trophic niche partitioning. Most likely, partitioning occurred with respect to enemies such as pathogenic fungi. Alternatively, similar effects on tree growth would have occurred if fungicide had eliminated positive effects of a higher diversity of beneficial fungi (e.g. mycorrhizal symbionts) that may have occurred in mixed tree species communities. [ABSTRACT FROM AUTHOR]

Summary: Many plant species produce multiple leaf flushes during the growing season, which might have major consequences for within‐plant variation in chemistry and species interactions. Yet, we lack a theoretical or empirical framework for how differences among leaf flushes might shape variation in damage by insects and diseases.We assessed the impact of leaf flush identity on leaf chemistry, insect attack and pathogen infection on the pedunculate oak Quercus robur by sampling leaves from each leaf flush in 20 populations across seven European countries during an entire growing season.The first leaf flush had higher levels of primary compounds, and lower levels of secondary compounds, than the second flush, whereas plant chemistry was highly variable in the third flush. Insect attack decreased from the first to the third flush, whereas infection by oak powdery mildew was lowest on leaves from the first flush. The relationship between plant chemistry, insect attack and pathogen infection varied strongly among leaf flushes and seasons.Our findings demonstrate the importance of considering differences among leaf flushes for our understanding of within‐tree variation in chemistry, insect attack and disease levels, something particularly relevant given the expected increase in the number of leaf flushes with climate change. [ABSTRACT FROM AUTHOR]

Biodiversity effects on ecosystem functioning can be partitioned into complementarity effects, driven by many species, and selection effects, driven by few. Selection effects occur through interspecific abundance shifts (dominance) and intraspecific shifts in functioning. Complementarity and selection effects are often calculated for biomass, but very rarely for secondary productivity, that is, energy transfer to higher trophic levels. We calculated diversity effects for three functions: aboveground biomass, insect herbivory and pathogen infection, the latter two as proxies for energy transfer to higher trophic levels, in a grassland experiment (PaNDiv) manipulating species richness, functional composition, nitrogen enrichment, and fungicide treatment. Complementarity effects were, on average, positive and selection effects negative for biomass production and pathogen infection and multiple species contributed to diversity effects in mixtures. Diversity effects were, on average, less pronounced for herbivory. Diversity effects for the three functions were not correlated, because different species drove the different effects. Benefits (and costs) from growing in diverse communities, be it reduced herbivore or pathogen damage or increased productivity either due to abundance increases or increased productivity per area were distributed across different plant species, leading to highly variable contributions of single species to effects of diversity on different functions. These results show that different underlying ecological mechanisms can result in similar overall diversity effects across functions. [ABSTRACT FROM AUTHOR]

Insects are important models for studying immunity in an ecological and evolutionary context. Yet, most empirical work on the insect immune system has come from phenotypic studies meaning we have a limited understanding of the genetic architecture of immune function in the sexes.We use nine highly inbred lines to thoroughly examine the genetic relationships between a suite of commonly used immune assays (haemocyte count, implant encapsulation, total phenoloxidase activity, antibacterial zone of inhibition and pathogen clearance) and resistance to infection by three generalist insect pathogens (the gram‐negative bacterium Serratia marcescens, the gram‐positive bacterium Bacillus cereus and the fungus Metarhizium robertsii) in male and female Gryllodes sigillatus.There were consistent positive genetic correlations between haemocyte count, antibacterial and phenoloxidase activity and resistance to S. marcescens in both sexes, but these relationships were less consistent for resistance to B. cereus and M. robertsii. In addition, the clearance of S. marcescens was genetically correlated with the resistance to all three pathogens in both sexes. Genetic correlations between resistances to the different pathogen species were inconsistent, indicating that resistance to one pathogen does not necessarily mean resistance to another. Finally, while there is ample genetic (co)variance in immune assays and pathogen resistance, these genetic estimates differed across the sexes and many of these measures were not genetically correlated across the sexes, suggesting that these measures could evolve independently in the sexes.Our finding that the genetic architecture of immune function is sex and pathogen specific suggests that the evolution of immune function in male and female G. sigillatus is likely to be complex. Similar quantitative genetic studies that measure a large number of assays and resistance to multiple pathogens in both sexes are needed to ascertain if this complexity extends to other species. [ABSTRACT FROM AUTHOR]

Summary: Rice is a staple food crop worldwide, and its production is severely threatened by phloem‐feeding insect herbivores, particularly the brown planthopper (BPH, Nilaparvata lugens), and destructive pathogens. Despite the identification of many BPH resistance genes, the molecular basis of rice resistance to BPH remains largely unclear. Here, we report that the plant elicitor peptide (Pep) signalling confers rice resistance to BPH. Both rice PEP RECEPTORs (PEPRs) and PRECURSORs of PEP (PROPEPs), particularly OsPROPEP3, were transcriptionally induced in leaf sheaths upon BPH infestation. Knockout of OsPEPRs impaired rice resistance to BPH, whereas exogenous application of OsPep3 improved the resistance. Hormone measurement and co‐profiling of transcriptomics and metabolomics in OsPep3‐treated rice leaf sheaths suggested potential contributions of jasmonic acid biosynthesis, lipid metabolism and phenylpropanoid metabolism to OsPep3‐induced rice immunity. Moreover, OsPep3 elicitation also strengthened rice resistance to the fungal pathogen Magnaporthe oryzae and bacterial pathogen Xanthamonas oryzae pv. oryzae and provoked immune responses in wheat. Collectively, this work demonstrates a previously unappreciated importance of the Pep signalling in plants for combating piercing‐sucking insect herbivores and promises exogenous application of OsPep3 as an eco‐friendly immune stimulator in agriculture for crop protection against a broad spectrum of insect pests and pathogens. [ABSTRACT FROM AUTHOR]

Summary: The insect pathogenic fungus, Metarhizium anisopliae is a commercialized microbial agent used in biological control efforts targeting a diverse range of agricultural and other insect pests. The second step in the synthesis of a group of M. anisopliae α‐pyrone diterpenoids (termed subglutinols) involves the activity of a prenyltransferase family geranylgeranyl diphosphate synthase (product of the subD/MaGGPPS5 gene). Here, we show that targeted gene disruption of MaGGPPS5 results in earlier conidial germination and faster greater vegetative growth compared to the wild type (WT) parent and complemented strains. In addition, insect bioassays revealed that the ΔMaGGPPS5 mutant strain displayed significantly increased virulence, with a ~50% decrease in the mean lethal time (LT50, from 6 to 3 days) to kill (50% of) target insects, and an ~15–40‐fold decrease in the mean lethal dose (LC50). Metabolite profiling indicated increased accumulation in the ΔMaGGPPS5 mutant of select subglutinols (A, B and C) and destruxins (A, A2, B and B2), the latter a set of fungal secondary metabolites that act as insect toxins, with a concomitant loss of production of subglutinol 'analogue 45'. These data suggest that the increased virulence phenotype seen for the ΔMaGGPPS5 strain can, at least in part, be attributed to a combination of faster growth and increased insect toxin production, linking the production of two different secondary metabolite pathways, and represent a novel approach for the screening of isolates with enhanced virulence via modulation of terpenoid secondary metabolite biosynthesis. [ABSTRACT FROM AUTHOR]

Theory predicts that sexual selection should aid adaptation to novel environments, but empirical support for this idea is limited. Pathogens are a major driver of host evolution and, unlike abiotic selection pressures, undergo epidemiological and co‐evolutionary cycles with the host involving adaptation and counteradaptation. Because of this, populations harbor ample genetic variation underlying immunity and the opportunity for sexual selection based on condition‐dependent "good genes" is expected to be large. In this study, we evolved populations of Drosophila melanogaster in a 2‐way factorial design manipulating sexual selection and pathogen presence, using a gram‐negative insect pathogen Pseudomonas entomophila, for 14 generations. We then examined how the presence of sexual selection and the pathogen, as well as any potential interaction, affected the evolution of pathogen resistance. We found increased resistance to P. entomophila in populations that evolved under pathogen pressure, driven primarily by increased female survival after infection despite selection for resistance acting only on males over the course of experimental evolution. This result suggests that the genetic basis of resistance is in part shared between the sexes. We did not find any evidence of sexual selection aiding adaptation to pathogen, however, a finding contrary to the predictions of "good genes" theory. Our results therefore provide no support for a role for sexual selection in the evolution of immunity in this experimental system. [ABSTRACT FROM AUTHOR]

Natural products (NPs) have long been an important source of, and inspiration for, developing novel compounds to control weeds, pathogens and insect pests. In this review, we use a dataset of 800 historic, current and emerging crop protection compounds to explore the influence of NPs on the introduction of new crop protection compounds (fungicides, herbicides, insecticides) as a function of time. NPs, their semisynthetic derivatives (NPDs) and compounds inspired by NPs (NP mimics, NPMs) account for 17% of all crop protection compounds. NPs, NPDs, and NPMs have been a fairly constant source of new agrochemicals over the past 70 years. NP synthetic equivalents (NPSEs) is a fourth group of NP‐related crop protection compounds composed of synthetic compounds which by chance also happen to have an NP model (but are not involved in the discovery). If NPSE compounds are also included, then 50% of all crop protection compounds hypothetically could have had a NP origin. Similar trends also hold true for the impact of NPs on the discovery of new modes of action (MoA) or innovation in crop protection compounds as measured by the number of first‐in‐class compounds. NPs have had the largest impact on the numbers and global sales (2018 USD) of insecticides compared to fungicides and herbicides. The present analysis highlights NPs as a long‐standing and continuing source of new chemistry, new MoAs and innovation in crop protection compound discovery. © 2021 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

SUMMARY: Global warming and climate change are driving an alarming increase in the frequency and intensity of different abiotic stresses, such as droughts, heat waves, cold snaps, and flooding, negatively affecting crop yields and causing food shortages. Climate change is also altering the composition and behavior of different insect and pathogen populations adding to yield losses worldwide. Additional constraints to agriculture are caused by the increasing amounts of human‐generated pollutants, as well as the negative impact of climate change on soil microbiomes. Although in the laboratory, we are trained to study the impact of individual stress conditions on plants, in the field many stresses, pollutants, and pests could simultaneously or sequentially affect plants, causing conditions of stress combination. Because climate change is expected to increase the frequency and intensity of such stress combination events (e.g., heat waves combined with drought, flooding, or other abiotic stresses, pollutants, and/or pathogens), a concentrated effort is needed to study how stress combination is affecting crops. This need is particularly critical, as many studies have shown that the response of plants to stress combination is unique and cannot be predicted from simply studying each of the different stresses that are part of the stress combination. Strategies to enhance crop tolerance to a particular stress may therefore fail to enhance tolerance to this specific stress, when combined with other factors. Here we review recent studies of stress combinations in different plants and propose new approaches and avenues for the development of stress combination‐ and climate change‐resilient crops. [ABSTRACT FROM AUTHOR]

Upon sensing attack by pathogens and insect herbivores, plants release complex mixtures of volatile compounds. Here, we show that the infection of lima bean (Phaseolus lunatus L.) plants with the non‐host bacterial pathogen Pseudomonas syringae pv. tomato led to the production of microbe‐induced plant volatiles (MIPVs). Surprisingly, the bacterial type III secretion system, which injects effector proteins directly into the plant cytosol to subvert host functions, was found to prime both intra‐ and inter‐specific defense responses in neighbouring wild tobacco (Nicotiana benthamiana) plants. Screening of each of 16 effectors using the Pseudomonas fluorescens effector‐to‐host analyser revealed that an effector, HopP1, was responsible for immune activation in receiver tobacco plants. Further study demonstrated that 1‐octen‐3‐ol, 3‐octanone and 3‐octanol are novel MIPVs emitted by the lima bean plant in a HopP1‐dependent manner. Exposure to synthetic 1‐octen‐3‐ol activated immunity in tobacco plants against a virulent pathogen Pseudomonas syringae pv. tabaci. Our results show for the first time that a bacterial type III effector can trigger the emission of C8 plant volatiles that mediate defense priming via plant–plant interactions. These results provide novel insights into the role of airborne chemicals in bacterial pathogen‐induced inter‐specific plant–plant interactions. Our results demonstrated two significant progresses on microbe‐induced plant volatile (MIPV). First, out of intensive screening to identify bacterial determinant(s) that induce plant volatiles to increase bacterial immunity on neighbouring plant, we newly identified a bacterial type III effector HopP1 from Pseudomonas syringae pv. tomato corresponding to MIPV. Secondly, the bacterial type III effector HopP1 induces the production of C8 volatile organic compounds, 1‐octen‐3‐ol, 3‐octanone and 3‐octanol on lima bean that in turn interspecifically prime plant defense against virulent bacterial pathogen P. syrinage pv. tabaci on neighbouring plant Nicotiana benthamiana. To our best knowledge, this is the first studies that type III secretion system–dependent bacterial effectors induce plant volatiles. [ABSTRACT FROM AUTHOR]

Resistance to solar ultraviolet (UV) irradiation is crucial for field‐persistent control efficacies of fungal formulations against arthropod pests, because their active ingredients are formulated conidia very sensitive to solar UV wavelengths. This review seeks to summarize advances in studies aiming to quantify, understand and improve conidial UV resistance. One focus of studies has been on the many sets of genes that have been revealed in the postgenomic era to contribute to or mediate UV resistance in the insect pathogens serving as main sources of fungal insecticides. Such genetic studies have unveiled the broad basis of UV‐resistant molecules including cytosolic solutes, cell wall components, various antioxidant enzymes, and numerous effectors and signaling proteins, that function in developmental, biosynthetic and stress‐responsive pathways. Another focus has been on the molecular basis and regulatory mechanisms underlying photorepair of UV‐induced DNA lesions and photoreactivation of UV‐impaired conidia. Studies have shed light upon a photoprotective mechanism depending on not only one or two photorepair‐required photolyases, but also two white collar proteins and other partners that play similar or more important roles in photorepair via interactions with photolyases. Research hotspots are suggested to explore a regulatory network of fungal photoprotection and to improve the development and application strategies of UV‐resistant fungal insecticides. © 2021 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Summary: The phytohormones jasmonates (JAs) control plant development, growth, and defense against insects and pathogens. The Arabidopsis JA receptor Coronatine Insensitive 1 (COI1) interacts with ARABIDOPSIS SKP‐LIKE1 (ASK1)/ASK2 to form the SCFCOI1 E3 ligase and mediate JA responses. Here, we performed a genetic suppressor screen using the leaky coi1‐2 (COI1Leu245Phe) mutant for restored sensitivity to JA, and identified the intragenic suppressor mutation Leu59Phe, which was in the region connecting the F‐box and leucine‐rich repeats domains of COI1. The L59F substitution not only restores the COI1L245F function, but also the COI1Gly434Glu (coi1‐22rsp) function in JA responses, through recovering their interactions with ASK1 or ASK2 and their protein levels. The L59F change itself could not enhance the interactions between COI1 and ASK1/2, nor affect JA responses. The present study reveals that the Leu59Phe substitution compensates for the effect of some deleterious mutations in the JA receptor COI1. Significance Statement: Jasmonate (JA) regulates plant growth, development, and defense. Our genetic suppressor screen of the leaky JA receptor mutant coi1‐2 (COI1Leu245Phe) reveals that the intragenic suppressor mutation Leu59Phe compensates for the effect of the deleterious mutations L245F and Gly434Glu in COI1 through facilitating the COI1‐ASK1/2 interactions and COI1 protein levels. [ABSTRACT FROM AUTHOR]

Summary: Biological control potential of insect‐pathogenic fungi against pests is an overall output of various cellular processes regulated by signalling and epigenetic networks. In Beauveria bassiana, mono/di/trimethylation of histone H3 Lys 4 (H3K4me1/me2/m3) was abolished by inactivation of the histone lysine methyltransferase SET1/KMT2, leading to marked virulence loss, reductions in conidial hydrophobicity and adherence to insect cuticle, impeded proliferation in vivo, severe defects in growth and conidiation, and increased sensitivities to cell wall perturbation, H2O2 and heat shock. Such compromised phenotypes correlated well with transcriptional abolishment or repression of carbon catabolite‐repressing transcription factor Cre1, classes I and II hydrophobins Hyd1 and Hyd2 required for cell hydrophobicity, key developmental regulators, and stress‐responsive enzymes/proteins. Particularly, expression of cre1, which upregulates hyd4 upon activation by KMT2‐mediated H3K4me3 in Metarhizium robertsii, was nearly abolished in the Δset1 mutant, leading to abolished expression of hyd1 and hyd2 as homologues of hyd4. These data suggest that the SET1‐Cre1‐Hyd1/2 pathway function in B. bassiana like the KMT2‐Cre1‐Hyd4 pathway elucidated to mediate pathogenicity in M. robertsii. Our findings unveil not only a regulatory role for the SET1‐cored pathway in fungal virulence but also its novel role in mediating asexual cycle in vitro and stress responses in B. bassiana. [ABSTRACT FROM AUTHOR]

Summary: Chromatin transitions are mediated in part by acetylation/deacetylation post‐translational modifications of histones. Histone deacetylases, e.g. sirtuins (Sir‐proteins), repress transcription via promotion of heterochromatin formation. Here, we characterize the Sir2 class III histone deacetylase (BbSir2) in the environmentally and economically important fungal insect pathogen, Beauveria bassiana. BbSir2 is shown to contribute to the deacetylation of lysine residues on H3 and H4 histones. Targeted gene knockout of BbSir2 resulted in impaired asexual development, reduced abilities to utilize various carbon/nitrogen sources, reduced tolerance to oxidative, heat, and UV stress, and attenuated virulence. ΔBbSir2 cells showed disrupted cell cycle development and abnormal hyphal septation patterns. Proteomic protein acetylation analyses of wild type and ΔBbSir2 cells revealed the differential abundance of 462 proteins and altered (hyper‐ or hypo‐) acetylation of 436 lysine residues on 350 proteins. Bioinformatic analyses revealed enrichment in pathways involved in carbon/nitrogen metabolism, cell cycle control and cell rescue, defence and mitochondrial functioning. Critical targets involved in virulence included LysM effector proteins and a benzoquinone oxidoreductase implicated in detoxification of cuticular compounds. These data indicate broad effects of BbSir2 on fungal development and stress response, with identification of discrete targets that can account for the observed (decreased) virulence phenotype. [ABSTRACT FROM AUTHOR]

Summary: Entomopathogenic fungi such as Metarhizium rileyi and Beauveria bassiana are widely used insect biological control agents. Little, however, is known concerning genetic or enzymatic factors that differentiate the mechanisms employed by these two fungal pathogens to infect target hosts. Infection by either of these organisms is known to increase levels of the growth and molting hormone, ecdysone, which also regulates the expression of a number of innate immune pathways. M. rileyi, but not B. bassiana, has apparently evolved an ecdysteroid‐22‐oxidase (MrE22O) that inactivate ecdysone. We show that deletion of MrE22O impaired virulence compared with the wild‐type strain, with an increase in ecdysone titer seen in hosts that was coupled to an increase in the expression of antimicrobial genes. An M. rileyi strain engineered to overexpress MrE22O (MrE22OOE), as well as trans‐expression in B. bassiana (Bb::MrE220OE) resulted, in strains displaying enhanced virulence and dampening of host immune responses compared with their respective wild‐type parental strains. These results indicate that ecdysone plays an important role in mediating responses to fungal infection and that some insect pathogenic fungi have evolved mechanisms for targeting this hormone as a means for facilitating infection. [ABSTRACT FROM AUTHOR]

Summary: Genomic data have identified a class of fungal specific transcription factors (FsTFs) that are thought to regulate unique aspects of fungal gene expression, although the functions of many of these proteins remain unknown. Here, a novel FsTF (BbStf1), which features a leucine zipper dimerization domain and a fungal transcription factor regulatory middle homology region, was characterized in Beauveria bassiana, a filamentous insect fungal pathogen. Transcriptional activation and nuclear localization were experimentally confirmed for BbStf1. Disruption of Bbstf1 resulted in increased tolerance to oxidative stress and cell wall perturbation, accompanied by increased peroxidase (POD) and superoxide dismutase (SOD) activities and ratio of reduced/oxidized glutathione (GSH/GSSG), and by thickened cell wall and altered composition. Gene expression profile analysis revealed that transcription patterns of antioxidant enzyme and cell wall integrity‐involved genes were altered in the ∆Bbstf1, including some BbStf1‐targeted genes clarified with evidence. The ∆Bbstf1 strain displayed greater virulence to Galleria mellonella in the bioassays through both topical infection and intrahaemocoel injection due to more rapid proliferation in the haemocoel as compared to the wild‐type strain. Altogether, BbStf1 acts as a negative regulator of antioxidant response, cell wall integrity and virulence in B. bassiana. [ABSTRACT FROM AUTHOR]

The generation of new ideas and scientific hypotheses is often the result of extensive literature and database searches, but, with the growing wealth of public and private knowledge, the process of searching diverse and interconnected data to generate new insights into genes, gene networks, traits and diseases is becoming both more complex and more time‐consuming. To guide this technically challenging data integration task and to make gene discovery and hypotheses generation easier for researchers, we have developed a comprehensive software package called KnetMiner which is open‐source and containerized for easy use. KnetMiner is an integrated, intelligent, interactive gene and gene network discovery platform that supports scientists explore and understand the biological stories of complex traits and diseases across species. It features fast algorithms for generating rich interactive gene networks and prioritizing candidate genes based on knowledge mining approaches. KnetMiner is used in many plant science institutions and has been adopted by several plant breeding organizations to accelerate gene discovery. The software is generic and customizable and can therefore be readily applied to new species and data types; for example, it has been applied to pest insects and fungal pathogens; and most recently repurposed to support COVID‐19 research. Here, we give an overview of the main approaches behind KnetMiner and we report plant‐centric case studies for identifying genes, gene networks and trait relationships in Triticum aestivum (bread wheat), as well as, an evidence‐based approach to rank candidate genes under a large Arabidopsis thaliana QTL. KnetMiner is available at: https://knetminer.org. [ABSTRACT FROM AUTHOR]

Summary: Cotton (Gossypium hirsutum) is constantly attacked by pathogens and insects. The most efficient control strategy is to develop resistant varieties using broad‐spectrum gene resources. Several resistance loci harboured by superior varieties have been identified through genome‐wide association studies. However, the key genes and/or loci have not been functionally identified. In this study, we identified a locus significantly associated with Verticillium wilt (VW) resistance, and within a 145.5‐kb linkage disequilibrium, two non‐specific lipid transfer protein genes (named GhnsLTPsA10) were highly expressed under Verticillium pathogen stress. The expression of GhnsLTPsA10 significantly increased in roots upon Verticilliumdahliae stress but significantly decreased in leaves under insect attack. Furthermore, GhnsLTPsA10 played antagonistic roles in positively regulating VW and Fusarium wilt resistance and negatively mediating aphid and bollworm resistance in transgenic Arabidopsis and silenced cotton. By combining transcriptomic, histological and physiological analyses, we determined that GhnsLTPsA10‐mediated phenylpropanoid metabolism further affected the balance of the downstream metabolic flux of flavonoid and lignin biosynthesis. The divergent expression of GhnsLTPsA10 in roots and leaves coordinated resistance of cotton against fungal pathogens and insects via the redirection of metabolic flux. In addition, GhnsLTPsA10 contributed to reactive oxygen species accumulation. Therefore, in this study, we elucidated the novel function of GhnsLTP and the molecular association between disease resistance and insect resistance, balanced by GhnsLTPsA10. This broadens our knowledge of the biological function of GhnsLTPsA10 in crops and provides a useful locus for genetic improvement of cotton. Significance Statement: Cotton (Gossypium hirsutum) fibre quality and yield often decline sharply when infected with various diseases and insects. Here, we identified a locus which links two non‐specific lipid transfer proteins in cotton. The divergent tissue expression of the genes in the roots and leaves coordinated resistance of cotton to pathogens and insects via redirection of metabolic flux. [ABSTRACT FROM AUTHOR]

Summary: Phytohormone, particularly jasmonate (JA) and salicylate (SA) signaling, plays a central role in plant responses to herbivore and pathogen attack. Generally, SA mediates resistance responses against biotrophic pathogens and phloem‐feeding insects, while JA mediates responses against necrotrophic pathogens and chewing insects. The phytohormonal responses mediating rice resistance to a piercing‐sucking herbivore, the brown planthopper (BPH), remains unknown.Here, we combined transcriptome analysis, hormone measurements, genetic analysis and a field study to address this issue.Infestation by BPH adult females resulted in significant transcriptional reprograming. The upregulated genes were enriched in the JA signaling pathway. Consistently, the concentrations of JAs, but not SA, were dramatically increased in response to BPH attack. Two JA‐deficient lines (AOC and MYC2 knockout) and two SA‐deficient lines (nahG overexpression and NPR1 knockout) were constructed. BPH performed better on JA‐deficient lines than on wild‐type (WT) plants, but similarly on SA‐deficient and WT plants. During BPH attack, the accumulation of defensive secondary metabolites was attenuated in JA‐deficient lines compared with WT plants. Moreover, MYC2 mutants were more susceptible to planthoppers than WT plants in nature.This study reveals that JA signaling functions in rice defense against BPH. [ABSTRACT FROM AUTHOR]

BACKGROUND: It has been suggested that entomopathogenic fungi can be introduced into plants as endophytes potentially leading to insect control. Here, we sought to identify specific strains of the insect pathogenic fungus, Beauveria bassiana that would form endophytic associations with tobacco (Nicotiana benthamiana) benefitting host plant growth and/or resistance against insect pests and pathogens. RESULTS: Tobacco seeds were inoculated with six different B. bassiana strains and entophytic colonization, plant growth, and resistance to pathogens and insect pests were evaluated over a 50 day-period. Although all the strains could colonize seedlings, 90% seedling colonization was seen for four strains. Fungal cells could be detected in stems more readily than in leaf and root tissues. Colonization by B. bassiana boosted plant growth with an increased photosynthetic rate, chlorophyll content, and stomatal and trichome density seen in fungal treated plants. Tobacco seedlings colonized by specific B. bassiana strains displayed significantly increased tolerance/resistance against bacterial and fungal pathogens. B. bassiana-colonized seedlings also displayed higher resistance to aphids (Myzus persicae) as compared to untreated controls. Colonization by B. bassiana was shown to trigger both of the salicylic acid (SA) and jasmonate acid (JA) defense pathways, but SA pathway was upregulated much more than JA pathway for some of the tested strains. CONCLUSION: Specific strains of B. bassiana can be introduced into host plants as endophytes, resulting in promotion of host plant growth, increased resistance to microbial pathogens, and/or increased resistance to insect pests. [ABSTRACT FROM AUTHOR]

Light is important for plants as an energy source and a developmental signal, but it can also cause stress to plants and modulates responses to stress. Excess and fluctuating light result in photoinhibition and reactive oxygen species (ROS) accumulation around photosystems II and I, respectively. Ultraviolet light causes photodamage to DNA and a prolongation of the light period initiates the photoperiod stress syndrome. Changes in light quality and quantity, as well as in light duration are also key factors impacting the outcome of diverse abiotic and biotic stresses. Short day or shady environments enhance thermotolerance and increase cold acclimation. Similarly, shade conditions improve drought stress tolerance in plants. Additionally, the light environment affects the plants' responses to biotic intruders, such as pathogens or insect herbivores, often reducing growth‐defence trade‐offs. Understanding how plants use light information to modulate stress responses will support breeding strategies to enhance crop stress resilience. This review summarizes the effect of light as a stressor and the impact of the light environment on abiotic and biotic stress responses. There is a special focus on the role of the different light receptors and the crosstalk between light signalling and stress response pathways. Light can be stressful for plants and the light environment (quality, quantity and duration of illumination) influences the responses of plants to biotic and abiotic stresses through diverse connections between the light and stress signaling pathways. [ABSTRACT FROM AUTHOR]

The capability of synthetic pesticides to manage weeds, insect pests and pathogens in crops has diminished due to evolved resistance. Sustainable management is thus becoming more challenging. Novel solutions are needed and, given the ubiquity of biologically active secondary metabolites in nature, such compounds require further exploration as leads for novel crop protection chemistry. Despite improving understanding of allelochemicals, particularly in terms of their potential for use in weed control, their interactions with multiple biotic kingdoms have to date largely been examined in individual compounds and not as a recurrent phenomenon. Here, multi‐kingdom effects in allelochemicals are introduced by defining effects on various organisms, before exploring current understanding of the inducibility and possible ecological roles of these compounds with regard to the evolutionary arms race and dose–response relationships. Allelochemicals with functional benefits in multiple aspects of plant defence are described. Gathering these isolated areas of science under the unified umbrella of multi‐kingdom allelopathy encourages the development of naturally‐derived chemistries conferring defence to multiple discrete biotic stresses simultaneously, maximizing benefits in weed, insect and pathogen control, while potentially circumventing resistance. © 2020 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Summary: The filamentous fungus Beauveria bassiana, an insect fungal pathogen, is widely used for pest biocontrol. Aerial conidia are infectious propagules, and their yield and viability greatly affect the field application of this fungus; however, little is known about the molecular regulatory mechanism of the triggered conidiation. In the present study, we find that the secondary metabolite regulator BbSmr1 is involved in the regulation of asexual conidiation development and stress response in B. bassiana. A deficiency in Bbsmr1 results in a prominent fluffy‐like phenotype on solid medium, decreased conidial yield, accelerated conidial germination, as well as increased tolerance to H2O2 stress and cell wall inhibitors. The deletion of Bbsmr1 also leads to thickened conidial cell walls and changed cell epitopes. Overexpressing either BbbrlA or BbabaA in the ∆Bbsmr1 strain can rescue the phenotypes of conidial development and stress response. BbSmr1 activates BbbrlA transcription by directly binding to the A4GA3 sequence of the BbbrlA promoter. BbBrlA in turn binds to the promoter of Bbsmr1 and negatively regulates the expression of Bbsmr1. These results indicate that BbSmr1 positively regulates conidial development in B. bassiana by activating the central development pathway BrlA‐AbaA‐WetA and provides insights into the developmental regulatory mechanism of entomopathogenic fungi. [ABSTRACT FROM AUTHOR]

SUMMARY: Indole‐3‐carbinol (I3C), a hydrolysis product of indole‐3‐methylglucosinolate, is toxic to herbivorous insects and pathogens. In mammals, I3C is extensively studied for its properties in cancer prevention and treatment. Produced in Brassicaceae, I3C reversibly inhibits root elongation in a concentration‐dependent manner. This inhibition is partially explained by the antagonistic action of I3C on auxin signaling through TIR1. To further elucidate the mode of action of I3C in plants, we have identified and characterized a novel Arabidopsis mutant tolerant to I3C, ICT1. This mutant was identified following screening of the Full‐length cDNA Over‐eXpression library (FOX) seed collection for root growth in the presence of exogenous I3C. ICT1 carries the AT2G19750 gene, which encodes an S30 ribosomal protein. Overexpression, but not knockout, of the S30 gene causes tolerance to I3C. The tolerance is specific to I3C, since ICT1 did not exhibit pronounced tolerance to other indole or benzoxazinoid molecules tested. ICT1 maintains I3C‐induced antagonism of auxin signaling, indicating that the tolerance is due to an auxin‐independent mechanism. Transcript profiling experiments revealed that ICT1 is transcriptionally primed to respond to I3C treatment. Significance Statement: Overexpression of the ribosomal S30 gene in Arabidopsis causes tolerance to the glucosinolate breakdown product indole‐3‐carbinol by an extra‐ribosomal, auxin‐independent mechanism. Transcript profiling experiments revealed that ICT1 is transcriptionally primed to respond to I3C treatment, as well as to oxidative and biotic challenges. [ABSTRACT FROM AUTHOR]