Host transcriptional and microbiome metatranscriptomic changes in soybean plants carrying the insect-pathogenic fungus Beauveria bassiana as an endophyte.

In soybean (Glycine max L. Merr. cv Kingsoy), NO(3) (-) assimilation in leaves resulted in production and transport of malate to roots (B Touraine, N Grignon, C Grignon [1988] Plant Physiol 88: 605-612). This paper examines the significance of this phenomenon for the control of NO(3) (-) uptake by roots. The net NO(3) (-) uptake rate by roots of soybean plants was stimulated by the addition of K-malate to the external solution. It was decreased when phloem translocation was interrupted by hypocotyl girdling, and partially restored by malate addition to the medium, whereas glucose was ineffective. Introduction of K-malate into the transpiration stream using a split root system resulted in an enrichment of the phloem sap translocated back to the roots. This treatment resulted in an increase in both NO(3) (-) uptake and C excretion rates by roots. These results suggest that NO(3) (-) uptake by roots is dependent on the availability of shoot-borne, phloem-translocated malate. Shoot-to-root transport of malate stimulated NO(3) (-) uptake, and excretion of HCO(3) (-) ions was probably released by malate decarboxylation. NO(3) (-) uptake rate increased when the supply of NO(3) (-) to the shoot was increased, and decreased when the activity of nitrate reductase in the shoot was inhibited by WO(4) (2-). We conclude that in situ, NO(3) (-) reduction rate in the shoot may control NO(3) (-) uptake rate in the roots via the translocation rate of malate in the phloem.

Recent studies have shown that entomopathogenic fungi may have beneficial effects on plants such as growth promoters, phytopathogen antagonists and herbivory protection agents. The potential of the association of entomopathogenic fungi with soybean cultivation has not been revealed. In this sense, the objective of this study was to determine the effects of entomopathogenic fungi on the development of important soybean pests inoculated during planting of this crop. The effects of three entomopathogenic fungi, Metarhizium sp. indet. 1 ESALQ-1638, Beauveria bassiana ESALQ-3399 and Isaria fumosorosea ESALQ-3422, in the development and feeding preference of caterpillars Chrysodeixis includens and Helicoverpa armigera, and whitefly Bemisia tabaci adults and nymphs, after inoculation in soybean plants BRS 232 in a greenhouse. Mortality and biological parameters of the pests were evaluated in individuals fed on leaf discs and in whole soybean plants that were inoculated with the fungi. In addition, we investigated the persistence of entomopathogenic fungi in soybean plants and substrate, and the nutritional status carried out through leaf analysis of plants. The mortalities observed in C. includens caterpillars that fed leaf discs of the plants inoculated with the entomopathogenic fungi were significantly higher (33% -65%) than in the control (12% -13%). Mortality results in the whole plant experiment were similar to leaf discs, but the differences were statistically significant in only one of the two experiments. The H. armigera mortalities in fungi-inoculated plants varied from 36% to 60% while in the control it was less than 16%, both with leaves and whole plants, but these differences were not statistically significant. In general, caterpillars that fed on fungus inoculated plants had lower leaf consumption and both caterpillars or pupae reached lower weights than those reared on uninoculated plants. The period of caterpillars to pupae was equal to or greater in treatments with fungi. In the multiple choice tests, C. includens and H. armigera larvae, in general, preferred to feed on leaves inoculated with the fungi, especially with B. bassiana. On the other hand, B. tabaci preferred the uninoculated plants, where larger numbers of nymphs were observed. The inoculation of the soybean plants with the fungi did not alter the nutritional content of the leaves in relation to the uninoculated plants. The fungi remained in high concentrations in the substrate for 45 days, and after 60 days the density of Metarhizium sp. indet. 1 ESALQ-1638 was superior to the other fungi. These results reveal that the entomopathogenic fungi present potential to be used via substrate inoculation during planting.

The search for effective and environmentally sound measures to fight against plant diseases caused by phytopathogenic microorganisms is of great importance. It is especially important to investigate alternative measures to protect cultivated plants that combine elements beneficial to human health such as iodine and selenium. Purpose. The study of physiological and biochemical changes in soybean leaves after artificial inoculation of plants with different strains of phytopathogenic bacteria on the background of pre-sowing treatment of seeds with a solution of iodine-selenium (I-Se) chelates. Methods. Soybean plants of the Artemis variety were grown in field conditions. Before sowing, the seeds were treated with a 1% I-Se chelated solution (I — 80 mg/L and Se citrate — 0.05 mg/L). The experimental plants were inoculated with phytopathogenic bacteria from the microbiological collection of the Zabolotny Institute of Microbiology and Virology of the National Academy of Sciences, namely Pseudomonas savastanoi pv. glycinea IMВ B-9190, P. agglomerans IMВ B-9185, and P. syringae pv. syringae IMВ B-8531. The contents of chlorophyll-a, b and carotenoids in the leaves were determined by extraction in DMSO followed by spectrophotometry. Catalase activity was determined by the method of titrimetric permanganatometry with a 0.01M solution of KMnO4, the activity to non-specific peroxidases — according to Boyarkin’s method. Evaluation of the photochemical activity of photosynthesis according to the parameters F0, Fv/Fm, and RFd was carried out by the method of induction of chlorophyll fluorescence using a portable device «Floratest». Statistical processing of experimental data was carried out using the built-in functions of the Microsoft Excel program. Results. The increase of peroxidase activity of leaves was revealed after both pre-sowing treatment with 1% I-Se solution of intact plants and inoculation of them with different strains of bacterial pathogens in the following order: I-Se > I-Se+P. syringae pv. syringae 8531 > I-Se+P. agglomerans 9185 > I-Se+P. savastanoi pv. glycinea 9190. The catalase activity of leaves tissues increased only when infected with a specific pathogen P. savastanoi pv. glycinea 9190 (by 20.6%). After artificial inoculation with strains of both specific and facultative bacterial pathogens and the pre-sowing treatment with I-Se, there was observed an increase in the quantum efficiency of PSII (Fv /Fm) and fluorescence in decline index (Rfd). An increase in the content of chlorophyll-a (by 18%), b and carotenoids (by 7%) in the leaves after the pre-sowing treatment with I-Se has been shown. The content of chlorophyll-a in soybean leaves due to pre-sowing treatment with I-Se had the most significant increase after inoculation of P. agglomerans 9185 (20%). Due to the inoculation with a specific pathogen P. savastanoi pv. glycinea 9190 (after the pre-sowing treatment with I-Se), the content of chlorophyll-a tended to decrease, and the content of chlorophyll-b decreased by 7%. The carotenoid content in leaves increased significantly at inoculation of plant with facultative pathogens: P. agglomerans 9185 (by 28.2%) and P. savastanoi pv. syringae 8531 (by 20.7%). The chlorophyll a/b ratio increased in all experimental variants. Conclusions. 1. It was found that pre-sowing seed treatment with 1% I-Se chelated solution results in increasing disease resistance in nonspecific adult soybean plants, including increasing their thermotolerance. This is evidenced by increasing the peroxidase activity of leaves and the content of photosynthetic pigments in natural conditions: chlorophyll-a and carotenoids. 2. Inoculation of soybean plants with a specific pathogen causes an increase in catalase and peroxidase activities in leaves. The significant increase in peroxidase activity after plant inoculation with facultative pathogens was shown. 3. A significant increase in the content of chlorophyll-a in soybean leaves after inoculation with P. agglomerans 9185 and pre-sowing treatment with I-Se was observed. The significant reduction of chlorophyll-b in leaves due to the inoculation of plants with P. savastanoi pv. glycinea 9190 and pre-sowing treatment of the seeds with I-Se was shown. The most significant increase in the content of carotenoids in leaves was detected after inoculation of plants with facultative pathogens — P. agglomerans 9185 and P. syringae pv. syringae 8531. 4. Significant stimulation of both maximum quantum yield of PSII photochemistry (Fv /Fm) and the rate of carbon assimilation (Rfd) due to the pre-sowing seed treatment with I-Se and inoculation of plants with different strains of phytopathogens was observed. It resulted from the activation of antioxidant systems and increased need for assimilates due to changes in plant metabolism.

Background Endophytic fungi are microorganisms that live within plant tissues without causing disease symptoms, playing a crucial role in enhancing plant resistance against pathogens and insect pests while simultaneously promoting plant growth through various mechanisms. This systematic review analyzes 47 research articles published between 2020 and 2025, examining the role of endophytic fungi. The literature search was conducted in Scopus and PubMed databases using relevant keywords, initially yielding 2,730 records that were subsequently filtered based on four inclusion criteria: (i) Studies must examine interactions between endophytic fungi and plants; (ii) studies must include plant defense mechanisms induced by endophytic fungi; (iii) studies must demonstrate the fungi’s entomopathogenic capabilities; and (iv) studies must show the fungi’s ability to enhance plant growth. Results The analysis revealed that Beauveria bassiana was the most extensively studied endophytic fungus species (59.15% of studies), particularly in food crops such as rice, corn, and legumes. The most frequently reported plant resistance mechanisms involved activation of ISR/SAR pathways and increased production of defensive compounds. As entomopathogens, endophytes demonstrated high efficacy against target insects through cuticle colonization and toxin production, while their growth-promoting capabilities were evident through enhanced nutrient uptake and phytohormone production. A systemic approach that integrates all these aspects can provide more effective and sustainable pest control solutions, yet the percentage discussed in this study is still limited to only 21.27%, even though the integration of the three observation parameters is considered more strategic and efficient. However, endophytic fungi’s effectiveness was found to be highly dependent on environmental factors and plant genotype. Conclusion Although research on endophytic fungi continues to expand, integrative evaluations of their roles in plant defense, insect suppression, and growth enhancement remain limited.The study recommends: (1) exploring indigenous isolates from different ecosystems; (2) integrating multifunctional approaches using endophytic fungi; and (3) developing more stable bioformulations. These findings provide an important foundation for utilizing endophytic fungi as multifunctional biocontrol agents in sustainable agriculture.

Abstract. Lestari YA, Verawaty M, Herlinda S. 2022. Development of Spodoptera frugiperda fed on young maize plant’s fresh leaves inoculated with endophytic fungi from South Sumatra, Indonesia. Biodiversitas 23: 5056-5063. The endophytic entomopathogenic fungi are needed to control the Spodoptera frugiperda larvae hiding inside the maize plants. This research aimed to assess the effect of young maize inoculated with endophytic fungi on the development of S. frugiperda. The fungal isolates used for the bioassay were Beauveria bassiana JgSPK isolate (GenBank acc. no. MZ356494), B. bassiana JgCrJr isolate (GenBank acc. no. MZ356497), and Metarhizium anisopliae CaTpPga isolates (GenBank acc. no. MZ242073). Beauveria bassiana (JgSPK and JgCrJr isolates) and M. anisopliae (CaTpPga isolate) colonized young maize plant significantly reduced the pupae and adult emergence, adult longevity, eggs laid, and viable eggs of S. frugiperda. The fungi also significantly enhanced larval mortality compared to non-colonized ones. The larval mortality caused by M. anisopliae CaTpPga isolate (57.67%) was highest among other treatments but not significantly different from those treated with B. bassiana JgSPK isolate (51.33%). Furthermore, the developmental time (eggs, larvae, pupae stages, and lifespan) of S. frugiperda fed on leaves colonized with endophytic fungi significantly increased compared to non-colonized ones. So, B. bassiana and M. anisopliae inoculated as seed treatments caused negative effects on the development of S. frugiperda. These findings highlight the potential of endophytic B. bassiana and M. anisopliae from South Sumatra to protect maize against S. frugiperda.

Introducción: Algunos hongos entomopatógenos actúan como endófitos y son promotores del crecimiento. Estos beneficios pueden ser explicados por mejoras en procesos fisiológicos. En esta investigación se evaluó el efecto de cepas comerciales de hongos endófitos entomopatógenos y de aislados de suelos agrícolas del estado de San Luis Potosí (HEE) sobre el crecimiento, fotosíntesis, intercambio de gases y producción en plantas de chile poblano, considerando el efecto del método de inoculación usado.Metodología: Se usó como modelo al chile poblano (Capsicum annuum L.) cultivado bajo condiciones de laboratorio y en invernadero. Se evaluaron siete cepas de HEE: tres aislados de suelo agrícola de San Luis Potosí, pertenecientes a los géneros Metarhizium. (aislado RV01), Paecilomyces. (RV05) y Penicillium (aislado SL14); dos cepas de los hongos entomopatógenos Beauveria bassiana [(Bals.-Criv.) Vuill. 1992] (aislado BB42) y Metarhizium anisopliae [(Metschn.) Sorokin 1883)] (aislado MA25) aisladas de insectos y dos cepas comerciales de B. bassiana (aislado BB09) y M. anisopliae (aislado MA28). Se preparó una solución de conidios y se probaron dos métodos: 1) inoculación en semilla; y 2) aspersión del sustrato y una segunda aplicación cuando emergió la primera hoja verdadera. Se incluyeron testigos en cada experimento (se inoculo agua y un agente surfactante). Se evaluaron parámetros fotosintéticos (eficiencia máxima y efectiva de PSII, disipación fotoquímica y no fotoquímica, tasa de transporte de electrones), intercambio de gases (tasa de asimilación neta, conductancia estomática y transpiración) y el porcentaje de colonización en hoja, tallo y raíces. Al final del experimento se midió la longitud de la raíz, biomasa seca total, de la parte aérea de la planta y de la raíz.Resultados: A los 33 días después de la inoculación se observó como la inoculación con RV01, MA25, BB09 y SL14 aumentaron la asimilación neta de CO2 y la conductancia estomática, respecto a los testigos, al ser inoculados por semilla o por aspersión. Inocular directamente las semillas con HEE mejoró significativamente la asimilación de CO2, la disipación fotoquímica y la eficiencia efectiva de PSII en comparación con plantas inoculadas por aspersión. El aislado RV05 sobresalió por los resultados observados en el invernadero, con mayor producción de biomasa total. Las plantas inoculadas por semilla mostraron un aumento en la producción de biomasa total, y en el peso seco de la parte aérea y de raíces con respecto a las plantas inoculadas por aspersión. Un mayor crecimiento en las plantas se asoció con la colonización endófita.Conclusiones: Los HEE aislados a partir de suelos agrícolas de San Luis Potosí pueden competir con cepas comerciales en la promoción del crecimiento de plantas de chile poblano en invernadero. La inoculación directa de HEE sobre la semilla genera mejores resultados, aunque con variaciones en función de la cepa.

Endophytic fungi from selected varieties of soybean (Glycine max L. Merr.) and corn (Zea mays L.) grown in an agricultural area of Argentina

Unlike animals, which breathe through airways lined with pathogen-trapping defenses, plants get air through tiny pores in their leaves that all but invite bacteria to sneak in. How, then, do plants keep them out? They slam their pores, or stomata, shut. Stomata are flanked by guard cells that swell when triggered by bacteria, thus closing the pores. Besides being fascinating in its own right, this defense response has implications for human health—stomata have recently been shown to block some, but not all, types of the fecal bacteria that can contaminate leafy greens and other fresh produce, causing food poisoning outbreaks. In this issue of PLOS Biology, Montillet, Leonhardt, and colleagues show that guard cells contain an enzyme called lipoxygenase that makes stomata close in response to pathogens, overturning a previous theory that this process is regulated by the plant hormone abscisic acid. Lipoxygenases have previously been linked to pathogen defenses in the plant Arabidopsis thaliana, and in the current work the researchers identified a lipoxygenase gene (LOX1) that is expressed in guard cells. To explore this gene's role in plant defenses, they sprayed LOX1-deficient A. thaliana with a strain of the bacterium Pseudomonas syringae that normally makes stomata close. However, they found that stomata barely closed in these mutant plants, showing that LOX1 is required for this defense against bacteria. Bolstering this conclusion, Montillet and colleagues also found that substrates and products of the LOX1 enzyme make stomata close. Lipoxygenases turn fatty acids into fatty acid hydroperoxides (FAHs), and turn FAHs into reactive electrophile species (RES) oxylipins. The researchers found that stomata closed in response to two fatty acids that are LOX1 substrates, as well as in response to LOX1-produced FAHs and RES oxylipins. Next, the researchers clarified the relative roles of LOX1 and abscisic acid (ABA), the plant hormone previously thought to mediate stomatal closure in this defense response. This set of experiments, which involved treating A. thaliana with a peptide from bacterial flagella that is known to activate plant defenses, yielded several lines of evidence that LOX1 and ABA activate guard cells via different pathways. For example, each pathway had two mitogen-activated protein kinases that were not in the other pathway. In addition, LOX1-produced RES oxylipins failed to activate OST1, a protein kinase in the ABA pathway. In contrast, RES oxylipins made stomata close in A. thaliana mutants that either lacked OST1 or could not synthesize ABA. Finally, stomata close within an hour of the flagellar peptide treatment, but ABA marker genes were not expressed, suggesting that ABA was not produced during this time period. Moreover, Montillet and colleagues discovered that only the LOX pathway includes another plant hormone called salicylic acid, which is required for stomatal closure in response to bacteria. They found that the RES oxylipins produced by LOX1 failed to activate guard cells in A. thaliana mutants that lacked salicylic acid. In contrast, ABA still activated guard cells in these salicylic acid–deficient mutants. Besides suggesting that ABA and LOX1 are in different pathways, this work suggests that the LOX1 pathway makes plants synthesize salicylic acid, and that this is a key step in activating guard cells to shut out bacteria. So what does trigger the ABA pathway? Guard cells also close in response to environmental conditions such as light and humidity, suggesting that ABA mediates stomatal closure in response to such abiotic factors rather than to biological ones. While the researchers conclude that the ABA and LOX1 pathways are distinct and have different triggers, they also stress that both are required for stomata to close in response to bacteria. This is because regardless of whether the trigger is biotic or abiotic, ABA is the main regulator of the membrane proteins that control osmotic pressure in guard cells, which is what determines whether stomata are open or shut. Notably, an ion channel called SLAC1 is required for both biotic and abiotic stomatal closure, suggesting that both the ABA and LOX1 pathways act on this membrane protein. These findings extend previous work showing that stomata are key players in the defense response of plants, and significantly advance our understanding of stomatal closure. This could ultimately help us protect people from food plants that can carry human pathogens. In addition, because stomata regulate water loss, teasing apart the abiotic and biotic pathways of stomatal closure could help us breed plants better suited to harsh environmental conditions. Montillet J-L, Leonhardt N, Mondy S, Tranchimand S, Rumeau D, et al. (2013) An Abscisic Acid-Independent Oxylipin Pathway Controls Stomatal Closure and Immune Defense in Arabidopsis. doi:10.1371/journal.pbio.1001513

BackgroundFungal endophytes produce many secondary metabolites that can reduce root rot diseases. Soybean is a particularly important crop worldwide. Endophytic fungi can be isolated, identified, and incorporated into sustainable agriculture for the biological control of many diseases.ResultsThe aim of this study was to isolate some endophytic fungi for controlling the most important diseases of soybean plants and to study the mechanisms underlying this biocontrol regarding the suppression of pathogens. Ten endophytic fungi were isolated from soybean plants. Among them, the 3 fungi isolates that exhibited a high percentage of antagonistic activity against Rhizoctonia solani, the causal pathogen of root rot disease of soybean plants, were identified as Trichoderma longibrachiatum S12, T. asperellum S11, and T. atroviride PHYTAT7. The 3 fungi isolates had the ability to produce pectinase and chitinase and to solubilize phosphors. Moreover, they produced siderophores and indole acetic acid (IAA), which have a strong effect on the growth of the plants. The 3 isolates reduced disease severity by 64, 60, and 55%, respectively than the infected control.ConclusionThe results suggest that certain endophytic fungi associated with soybean plants have potential for the management of root rot diseases in soybean. Moreover, these isolates can be considered as having a growth-promoting effect in soybean plants.

To understand the mechanism of biophoton emission, ROS and mitochondrial proteins were analyzed in soybean plants under flooding stress. Enzyme activity and biophoton emission were increased in the flooding stress samples when assayed in reaction mixes specific for antioxidant enzymes and reactive oxygen species; although the level of the hydroxyl radicals was increased at day 4 (2 days of flooding) compared to nonflooding at day 4, the emission of biophotons did not change. Mitochondria were isolated and purified from the roots of soybean plants grown under flooding stress by using a Percoll gradient, and proteins were analyzed by a gel-free proteomic technique. Out of the 98 mitochondrial proteins that significantly changed abundance under flooding stress, 47 increased and 51 decreased at day 4. The mitochondrial enzymes fumarase, glutathione-S-transferase, and aldehyde dehydrogenase increased at day 4 in protein abundance and enzyme activity. Enzyme activity and biophoton emission decreased at day 4 by the assay of lipoxygenase under stress. Aconitase, acyl CoA oxidase, succinate dehydrogenase, and NADH ubiquinone dehydrogenase were up-regulated at the transcription level. These results indicate that oxidation and peroxide scavenging might lead to biophoton emission and oxidative damage in the roots of soybean plants under flooding stress.

ABSTRACTEntomopathogenic fungi (EF) provide a potent biocontrol tool; also, their endophytic behavior has broadened their contribution to integrated pest management (IPM) and crop production. In this work, Beauveria bassiana and Metarhizium brunneum were applied to bread wheat (Triticum aestivum) seedlings to elucidate how fungal colonization influences plant growth and the relative expression of 24 genes involved in hormonal syntheses and plant immune mechanisms. A preliminary assay was used to determine the time needed for fungal colonization and assess its effect on wheat growth. Then, plant material collected at various times after inoculation (viz., 2, 8, 20, and 36 h and 9 and 15 days) was used to investigate gene expression by quantitative reverse transcription PCR (RT-qPCR). During the colonization time, B. bassiana and M. brunneum caused strong downregulation of most genes associated with plant immunity and the synthesis of hormones like auxin, cytokinin, and gibberellin. This effect was concomitant with a slowdown of endophytic-colonization-related plant growth until 19 days postinoculation (dpi). However, the wheat started to recover at 15 dpi, simultaneously with upregulation of auxin- and gibberellin-related genes. The results suggest that the EF trigger induced systemic resistance rather than acquired systemic resistance during early plant-microbe cross talk in wheat. Also, they confirm that the hormone and immune responses of wheat triggered by EF inoculation influenced plant growth, which can be useful with a view to optimizing management of these microorganisms for sustainable agriculture.IMPORTANCE Microbial control of insect and mite pests is a key tool to develop integrated pest management (IPM) and sustainable agriculture. Entomopathogenic fungi (EF) may have associations with the plants, playing additional ecological roles in the rhizosphere, in the phylloplane, and as plant endophytes. Beauveria bassiana 04/01TIP and Metarhizium brunneum 01/58Su are two strains that showed very good results either in pest control or plant growth promotion and would be good candidates to develop mycoinsecticides as an alternative to pesticides. However, deep knowledge about their interaction with the plant would let farmers optimize their use and understand the plant response, enhancing and promoting their broader contribution to IPM and crop production.

Endophytic fungus, usually treated as an entomopathogenic agent, can provide drought stress tolerance to red oak seedlings. Its effect is realized through root growth stimulation. Endophytic fungi are known to be active in the plant environmental stress alleviation. In this work, we proved the ability of endophytic Beauveria bassiana, which is almost exclusively treated as an entomopathogenic fungus, in mitigating drought stress in dehydrated red oak (Quercus rubra L.) seedlings. Despite small differences between experiments, in general, leaf relative water content and stomatal conductance were less reduced (ca. 50% and 15%, respectively), free proline did not accumulate over the control level, carbon isotope 13C discrimination/water use efficiency was not affected and root growth was stimulated at a similar plant transpiration area in the endophyte-colonised individuals. Regression analysis revealed that the root growth stimulation provided by the fungus under drought had the most important effect on their water status.

Summary There is increasing evidence that extrafloral (EF) nectaries, described in approximately 1000 plant species from more than 90 families, have a defensive function. Endophytic fungi are an important group of microorganisms asymptomatically colonizing host plants, and promoting their defences against natural enemies. We aimed at investigating the role of these microorganisms in inducing EF nectary defences in plants against herbivory. We conducted a full factorial experiment to study the effects of a soil‐borne endophytic fungus, Acremonium strictum, alone or in combination with the aphid, Aphis fabae, on the production of EF nectar and nectaries in broad beans. By manipulating the presence/absence of the fungus in the roots of the host plants and by inflicting herbivore damage at a specific time and location, we tested the hypothesis that endophyte inoculation induces EF‐mediated indirect defences. The quantity of EF nectar production and the number of EF nectaries produced were assessed by repeated samplings at fixed intervals. Endophytic inoculation of bean plants induced a significant short‐term increase in total EF nectar production and a significant prompt increase in number of EF nectaries per expanded leaf. On the other hand, aphid infestation resulted in a prolonged increase in total EF nectar production and a delayed induction of EF nectaries. Conversely, when plants were simultaneously inoculated with the endophyte and infested with aphids, both EF traits were significantly reduced. The effect of endophyte inoculation was further examined by recording the life history traits of Aphis fabae. Aphid performance was generally lower on inoculated plants; however, relative fecundity was the only fitness parameter significantly reduced on endophyte inoculated plants. The organism model in the present study serves as a model for investigating how endophytic colonization alters the response of EF nectary traits to herbivory. From a cost/benefit perspective, variable responses in EF‐mediated indirect defences as influenced by endophytes could be explained as trade‐offs in defence. In addition, other possibilities that may have contributed to the EF response patterns reported in this study are discussed.

Many fungi live intimately associated with plants and may benefit or harm the host plant. Improved knowledge of such interactions is needed for increasing plant health and crop productivity by implementation of fungal inoculants. Co-inoculations of different beneficial fungi offer the possibility to understand complex plant–microbe interactions that may be functionally complementary for improved plant production and protection. Here, we studied the individual and combined effects of the arbuscular mycorrhizal fungus (AMF) Funneliformis mosseae with three isolates of entomopathogenic fungi (EPF), representing Metarhizium brunneum, M. robertsii and Beauveria bassiana, on protection against the foliar phytopathogen Botrytis cinerea and on plant growth. Seedlings of tomato (Solanum lycopersicum L. var. Moneymaker) were inoculated in the substrate with AMF or EPF alone and in dual combinations under greenhouse conditions. Inoculation with the different EPF isolates reduced lesion sizes of B. cinerea on inoculated tomato leaves, but only in the experimental repetition that showed highest level of disease severity. The AMF F. mosseae had no additional effect on B. cinerea lesion size in combinations with EPF. In the experimental repetition with least disease severity, the AMF treatment led to limited increase of B. cinerea lesion sizes. In general, F. mosseae caused an increase in plant biomass, and the co-inoculations of AMF and EPF did in some combinations increase plant growth. Below-ground interactions between AMF and EPF were observed, as the presence of AMF in the roots was associated with a decrease of EPF root colonization densities. However, AMF colonization rates were unaffected by EPF presence. The study indicated a functional complementarity between EPF and AMF by suppressing phytopathogens and increasing plant growth, respectively. However, it further revealed the challenge of obtaining consistent results of plant–microbe-phytopathogen interactions, which must be overcome for future implementation of beneficial fungi as inoculants in plant production.

Endophytic fungi are increasingly studied for their ability to enhance plant performance in field crops, yet there are few equivalent studies in floricultural crops. Given the economic importance of these crops and pressures faced by growers to produce plants of high aesthetic quality, we surveyed the natural occurrence of foliar fungal endophytes in Knock Out ® roses to identify candidate beneficial isolates. We also tested the effects of entomopathogenic fungal inocula on marigold and zinnia plant growth using different application approaches. Our survey of Knock Out ® rose foliage collected from five sites within central Texas revealed at least 24 different fungal genera and 30 probable species, including some isolates providing plant stress tolerance and pathogens or antagonists of insects and nematode pests. The effects of entomopathogen inocula on plant growth varied with host plant (marigold vs. zinnia) and inoculation method (soil drench vs. seed soak). Plant responses were complex, but inoculation with Isaria fumosorosea Wize tended to have a negative effect on plant performance characteristics whereas Beauveria bassiana (Bals.-Criv.) Vuill. tended to have positive effects. When applied to marigold as a seedcoating, I. fumosorosea reduced germination, seedling fresh weight, and produced seedlings with a less compact form. By contrast, seeds inoculated with B. bassiana required less time to germinate, had higher germination rates, and increased the plant compactness. These results show that the impact of fungal entomopathogens applied as endophytes depends on the specific fungi-plant combination being examined. The effect of plant inoculation with entomopathogenic fungi within a pest management context requires further evaluation.