Aphid Attack Research Articles

Volatile cis-jasmone affects the tri-trophic interactions among the potato plants, the green peach aphid (Myzus persicae), and the parasitoid (Aphidius gifuensis)

New strategies for protecting crops from aphid attacks must be developed. The present study aimed to examine the effect of cis-Jasmone (CJ), an activator of plant defense, on potato plants. Plants were sprayed with an exogenous application of CJ at 12, 24, and 48 h; and the green peach aphid, Myzus persicae Sulzer, and its parasitoid, Aphidius gifuensis, were used to evaluate the tri-trophic interactions of the aphids, parasitoids, and plants. In this work, we examined that the adult M. persicae produced fewer nymphs on CJ-treated plants at 12, 24, and 48 h than on control plants. Furthermore, M. persicae nymphs that fed on CJ-treated plants at 48 h had a lower mean relative growth rate (MRGR). Moreover, the intrinsic rate of population increase (r) was significantly lowered in CJ-treated plants at 12, 24, and 48 h. CJ-treated plants at all time durations showed considerably less settlement of aphid than control plants. In the olfactometer bioassay, the parasitoid exhibited a prolonged duration in the arm treated with volatiles from CJ-treated plants at 12, 24, and 48 h in comparison to the control. Moreover, the salicylic acid and jasmonic acid marker gene expression levels were significantly upregulated by CJ-treatment. Surprisingly, aphids raised on CJ-treated potato plants showed higher transcriptional levels of detoxifying enzymes. The findings of this research will provide new insights into the possible applications of important volatile components like cis-jasmone in integrated pest management systems, in addition to enhancing our comprehension of the ways in which plant volatiles affect the crop community.

Aphid alarm pheromone mimicry in transgenic Chrysanthemum morifolium: insights into the potential of (E)-β-farnesene for aphid resistance.

(E)-β-Farnesene (EBF) serves as the primary component of the alarm pheromone used by most aphid pest species. Pyrethrum (Tanacetum cinerariifolium) exhibits tissue-specific regulation of EBF accumulation and release, effectively mimicking the aphid alarm signal, deterring aphid attacks while attracting aphid predators. However, cultivated chrysanthemum (Chrysanthemum morifolium), a popular and economically significant flower, is highly vulnerable to aphid infestations. In this study, we investigated the high expression of the pyrethrum EBF synthase (TcEbFS) gene promoter in the flower head and stem, particularly in the parenchyma cells. Subsequently, we introduced the TcEbFS gene, under the control of its native promoter, into cultivated chrysanthemum. This genetic modification led to increased EBF accumulation in the flower stem and young flower bud, which are the most susceptible tissues to aphid attacks. Analysis revealed that aphids feeding on transgenic chrysanthemum exhibited prolonged probing times and extended salivation durations during the phloem phase, indicating that EBF in the cortex cells hindered their host-location behavior. Interestingly, the heightened emission of EBF was only observed in transgenic chrysanthemum flowers after mechanical damage. Furthermore, we explored the potential of this transgenic chrysanthemum for aphid resistance by comparing the spatial distribution and storage of terpene volatiles in different organs and tissues of pyrethrum and chrysanthemum. This study provides valuable insights into future trials aiming for a more accurate replication of alarm pheromone release in plants. It highlights the complexities of utilizing EBF for aphid resistance in cultivated chrysanthemum and calls for further investigations to enhance our understanding of this defense mechanism.

Chrysanthemum (Chrysanthemum morifolium) CmHRE2-like negatively regulates the resistance of chrysanthemum to the aphid (Macrosiphoniella sanborni)

BackgroundThe growth and ornamental value of chrysanthemums are frequently hindered by aphid attacks. The ethylene-responsive factor (ERF) gene family is pivotal in responding to biotic stress, including insect stress. However, to date, little is known regarding the involvement of ERF transcription factors (TFs) in the response of chrysanthemum to aphids.ResultsIn the present study, CmHRE2-like from chrysanthemum (Chrysanthemum morifolium), a transcription activator that localizes mainly to the nucleus, was cloned. Expression is induced by aphid infestation. Overexpression of CmHRE2-like in chrysanthemum mediated its susceptibility to aphids, whereas CmHRE2-like-SRDX dominant repressor transgenic plants enhanced the resistance of chrysanthemum to aphids, suggesting that CmHRE2-like contributes to the susceptibility of chrysanthemum to aphids. The flavonoids in CmHRE2-like-overexpression plants were decreased by 29% and 28% in two different lines, whereas they were increased by 42% and 29% in CmHRE2-like-SRDX dominant repressor transgenic plants. The expression of Chrysanthemum-chalcone-synthase gene(CmCHS), chalcone isomerase gene (CmCHI), and flavonoid 3′-hydroxylase gene(CmF3’H) was downregulated in CmHRE2-like overexpression plants and upregulated in CmHRE2-like-SRDX dominant repressor transgenic plants, suggesting that CmHRE2-like regulates the resistance of chrysanthemum to aphids partially through the regulation of flavonoid biosynthesis.ConclusionCmHRE2-like was a key gene regulating the vulnerability of chrysanthemum to aphids. This study offers fresh perspectives on the molecular mechanisms of chrysanthemum-aphid interactions and may bear practical significance for developing new strategies to manage aphid infestation in chrysanthemums.

A tug-of-war to control plant emission of an airborne alarm signal

Aphids represent a major threat to crops. Hundreds of different viruses are aphid-borne. Upon aphid attack, plants release volatile organic compounds (VOCs) as airborne alarm signals to turn on the airborne defense (AD) of neighboring plants, thereby repelling aphids as well as reducing aphid fitness and virus transmission. This phenomenon provides a critical community-wide plant protection to fend off aphids, but the underlying molecular basis remains undetermined for a long time. In a recent article, Gong et al. established the NAC2-SAMT1 module as the core component regulating the emission of methyl-salicylate (MeSA), a major component of VOCs in aphid-attacked plants. Furthermore, they showed that SABP2 protein is critical for the perception of volatile MeSA signal by converting MeSA to Salicylic Acid (SA), which is the cue to elicit AD against aphids at the community level. Moreover, they showed that multiple viruses use a conserved glycine residue in the ATP-dependent helicase domain in viral proteins to shuttle NAC2 from the nucleus to the cytoplasm for degradation, leading to the attenuation of MeSA emission and AD. These findings illuminate the functional roles of key regulators in the complex MeSA-mediated airborne defense process and a counter-defense mechanism used by viruses, which has profound significance in advancing the knowledge of plant-pathogen interactions as well as providing potential targets for gene editing-based crop breeding.

Different Effects and Application of Methyl Jasmonate on Triticum aestivum L. by aphid Attack

Wheat (Triticum aestivum L.) widely grown in Pakistan during winter season. Aphid is one of the biological factors that inhibits seed germination and plant development. Methyl jasmonate is a plant growth regulator known to take part in defense responses against different types of stresses including Aphid attack. The current study was conducted to improve the growth of the wheat by the foliar application of Methyl jasmonate. Two wheat varieties (Shafaq and Gold) were be sown in plastic pots filled with 6 kg soil in each pot. After germination, wheat plants were treated with different Aphids. After three weeks of treatment data about survival percentage, root attributes, shoot attributes and nutrient analysis was be recorded using standard procedure. The experiment was be conducted under a complete randomized design (CRD) with three replicates and results was be deducted after statistical analysis. Different concentrations of methyl jasmonate (100 micromolar and 1mM) were applied to 20 days old wheat plant. Rhopalosiphum padi was allowed to infest the methyl jasmonate treated plants as well as non-treated plants. Control plants were covered with net and no concentration of methyl jasmonate were applied. Aphids were allowed to infest the plant for 48 hours, after that the plant from all treatments were sampled for all physiological studies. Methyl jasmonate treated plants as well as control plants were used for direct aphid population count after every week. Concluded results depicted that plants exposed to different concentrations of methyl jasmonate affected the root and shoot length, plant height which was further improved through MeJA supplementation.

Assessment of Mustard Genotypes against Aphid Attack (Lipaphis erysimi Kalt.) under Natural Field Conditions of Muzaffarpur (Bihar)

Assessment of Mustard Genotypes against Aphid Attack (Lipaphis erysimi Kalt.) under Natural Field Conditions of Muzaffarpur (Bihar)

GhMYC1374 regulates the cotton defense response to cotton aphids by mediating the production of flavonoids and free gossypol

Myelocytomatosis (MYC) transcription factors (TFs) in plants are well-known regulators of plant defense against herbivores. However, the role and mechanism of MYC TFs in cotton (Gossypium hirsutum L.) defense against cotton aphids (Aphis gossypii Glover) remain still elusive. Herein, on the basis of aphid-induced cotton transcriptome analysis, GhMYC1374, a cotton MYC2-like TF that was highly induced by cotton aphid attack, has been identified that confers cotton aphid resistance in cotton. GhMYC1374 was an intranuclear transcription factor with three domains: bHLH-MYC_N, RBR and bHLH_AtAIB_like. GhMYC1374 was induced under cotton aphid feeding, exogenous methyl jasmonate (MeJA) and salicylic acid (SA) treatments. GhMYC1374 transient overexpression in cotton plants enhanced cotton aphid-resistance, while GhMYC1374 silence through VIGS (virus induced gene silencing) decreased cotton aphid-resistance. GhMYC1374 transient overexpression of in cotton plants activated the phenylpropane pathway and promoted the synthesis of flavonoids, and resistance to thus enhanced the cotton resistance against aphids. In contrast, GhMYC1374 silence inhibited the biosynthesis of flavonoids. In addition, GhMYC1374 also positively activated the expression of the biosynthetic genes of free gossypol, leading to the high content of free gossypol. Taken together, our results suggest that GhMYC1374 is involved in the cotton defense response against cotton aphids by regulating the biosynthesis of flavonoids and free gossypol.

Utilization of crop wild relatives for biotic and abiotic stress management in Indian mustard [Brassica juncea (L.) Czern. & Coss.

Brassica juncea (L.) Czern. & Coss. (Indian mustard) is an economically important edible oil crop. Over the years, plant breeders have developed many elite varieties of B. juncea with better yield traits, but research work on the introgression of stress resilience traits has largely been lagging due to scarcity of resistant donors. Crop wild relatives (CWRs) are the weedy relatives of domesticated plant species which are left unutilized in their natural habitat due to the presence of certain undesirable alleles which hamper their yield potential, and thus, their further domestication. CWRs of B. juncea namely include Sinapis alba L. (White mustard), B. tournefortii Gouan. (African mustard), B. fruticulosa Cirillo (Twiggy turnip), Camelina sativa L. (Gold-of-pleasure), Diplotaxis tenuisiliqua Delile (Wall rocket), D. erucoides L. (White wall rocket), D. muralis L. (Annual wall rocket), Crambe abyssinica R.E.Fr. (Abyssinian mustard), Erucastrum gallicum Willd. (Common dogmustard), E. cardaminoides Webb ex Christ (Dogmustard), Capsella bursa-pastoris L. (Shepherds purse), Lepidium sativum L. (Garden Cress) etc. These CWRs have withstood several regimes of biotic and abiotic stresses over the past thousands of years which led them to accumulate many useful alleles contributing in resistance against various environmental stresses. Thus, CWRs could serve as resourceful gene pools for introgression of stress resilience traits into Indian mustard. This review summarizes research work on the introgression of resistance against Sclerotinia stem rot (caused by Sclerotinia sclerotiorum), Alternaria blight (caused by Alternaria brassicae), white rust (caused by Albugo candida), aphid attack, drought and high temperature from CWRs into B. juncea. However, various pre- and post-fertilization barriers due to different ploidy levels are major stumbling blocks in the success of such programmes, therefore, we also insightfully discuss how the advances made in -omics technology could be helpful in assisting various breeding programmes aiming at improvisation of stress resilience traits in B. juncea.

Plant Growth-Promoting Rhizobacteria and Chabazite Zeolite in the growth stimulation and protection of Sedum palmeri and Sedum sieboldii from aphid and red spider mite attack

Research objective: The aim of this research was to evaluate the interaction that can develop between zeolite and microorganisms with beneficial effects on both the growth of Sedum palmeri and Sedum sieboldii and in the defence against Aphis sedii and Tetranychus urticae. Materials and Methods: The experiments, which started in January 2023, were conducted in the CREA-OF greenhouses in Pescia (Pt), Tuscany, Italy (43°54′N 10°41′E). The plants were placed in pots with a diameter of 12, 10 plants per 3 replications, for a total of 30 seedlings per experiment. The Sedum trial included the following theses (irrigated and fertilised): peat 70% + pumice 30% (CTRL); peat 70% + pumice 10% + chabazite natural zeolite 20%; peat 70% + pumice 30% + microorganisms (Azospirillum brasilense, Pseudomonas kilonensis and Bacillus aryabhattai), 1g/Kg of substrate at the time of substrate preparation; peat 70% + pumice 10% + chabazite natural zeolite 20% and micro-organisms (the same as those used in the thesis described above) in the same dosage. A second parallel experiment to control aphids and red spider mite involved: water treatment; treatment for aphids and red spider mite (soft potassium soap and azadirachtin 2.5 ml/l once a week; Kanemite 3 ml/l once a week); treatment for aphids and the alternative red spider mite (micronised zeolite 15g/l and microorganisms 1g/l, once a week). Plant height, leaves and flowers number, vegetative weight, root volume and length, microorganisms in the substrate, number of plants affected by aphids and red spider mite were determined on 15 September 2023. Results and Discussion: The experiment showed that the use of chabazite zeolite in combination with microorganisms can indeed significantly improve the vegetative and root growth of Sedum palmeri and Sedum sieboldii plants. Differences in growth between the use of zeolite and microorganisms and the untreated control are evident, with a significant improvement when the two theses are combined for all agronomic parameters analysed. In the substrate analysis, a greater presence of microbial biomass was found in the theses with zeolite, microorganisms and zeolite together with microorganisms than in the control theses, with a greater superiority of microorganisms in the substrate when zeolite and microorganisms are used in combination. The trial with micronised zeolite and microorganisms showed a significant result on the control of aphids and red spider mites, with data comparable to those of treatment with conventional chemical products. Zeolites are used successfully in the cultivation of many crops. Including cereals, vegetables, grapes and other fruits. By enhancing the absorption ability of soil, zeolite enhance the long-term quality of soil by retaining nutrients. Conclusions: For agricultural production, zeolites must have uniform properties and unique characteristics, such as cation exchange capacity and pH. Especially in agriculture and plant cultivation, zeolites improve their exchange capacity with the soil and plants through microbial activity. By lowering the pH of the substrate, microorganisms are able to solubilise the minerals retained by the zeolites, making them more available to the roots. Furthermore, zeolites, when micronised on the leaves, do a good job of protecting plants from insects and fungi, especially when used as a preventive measure. This can also ensure a significant reduction in synthetic chemicals and improve plant protection when these strategies are used in combination.

USO DE INSETICIDAS BIOLÓGICOS NO CONTROLE DE INSETOS PRAGAS DAS CULTURAS DO SORGO E FEIJÃO

The project was developed at the IAC, in Votuporanga, São Paulo State, Brazil. The experimental design used was randomized blocks with four repetitions, using five treatments: sorghum culture: standard treatment (without insecticide application, T1); Colossus BT-2 (B. thugingiensis subsp. Kurstaki) and Comander (C. subtlesugae) at doses of 0.3 L ha-1 and 0.2 L ha-1, respectively (T2); 0.4 L ha-1 and 0.3 L ha-1, respectively (T3); 0.5 L ha-1 and 0.4 L ha-1, respectively (T4); application of chemical insecticides (T5); bean culture: standard treatment (without insecticide application, T1); Application of Ultron-S+A (S. spinosa) at doses of 0.2 L ha-1 (T2); 0.3 L ha-1 (T3); 0.4 L ha-1 (T4); application of chemical insecticides (T5). The plots were 5.0 x 5.0 m, totaling 25 m2. In sorghum culture was evaluated the incidence (%) of plants with the presence of caterpillars in the leaves; the incidence (%) of plants with caterpillars attack symptoms in the leaves; the incidence (%) of plants with the presence of aphids in the leaves; the incidence (%) of plants with symptoms of attack of aphids in the leaves; final stand ha-1 and grain yield ha-1. In bean culture was evaluated the incidence (%) of plants with the presence of caterpillars in the leaves; the incidence (%) of plants with symptoms of attack of caterpillars in the leaves; the incidence (%) of plants with the presence of thrips in the leaves; the incidence (%) of plants with thrips attack symptoms in the leaves; final stand ha-1 and grain yield ha-1.

Jasmonic acid impact on botanical and morpho-physiological characteristics of wheat (Triticum aestivum L.) infected by Aphid

Wheat (Triticum aestivum L.) is the most essential cereal crop among all other crops of Pakistan and belongs to the family poaceae. The experiment was performed to evaluate the response of exogenously applied jasmonic acid on wheat (Triticum aestivum L.) growth parameter against aphid attack. Two wheat varieties i.e., Fareed-2006 and Paktoon-2016 are cultivated in pots and different concentrations of Jasmonic acid (100 µM and 1 mM) were applied. Concluded results showed that aphid infested plants decreased root and shoot length, plant height, total soluble protein and chlorophyll contents but increased the POD and SOD contents, MDA contents, catalase, H2O2 concentrations and phenolics of wheat (Triticum aestivum) which was further improved through jasmonic acid application. Jasmonic acid treated plants showed better results than control and aphid infested plants. Jasmonic acid spray helped plants to recovery from aphid stress by increasing antioxidant enzyme synthesis, POD (Peroxidase), SOD (Superoxide dismutase) and CAT (Catalase). The results showed that JA sprayed plants have a reduced aphid population than controls plants. When compared to jasmonic acid (100 µM), the greater concentration of jasmonic acid (1mM) showed more effective. Use of jasmonic acid against devastating diseases seems to hold a more promising future in the pest management and agriculture sector.

Analysis of plant expression profiles revealed that aphid attack triggered dynamic defense responses in sorghum plant.

Sorghum [Sorghum bicolor (L.) Moench] is one of the most important cereal crops grown worldwide but is often attacked by greenbug (aphid). In response to aphid attack, host plant initiates a large transcriptional reorganization, leading to activation of the host defense genes in aphid-attacked plants. In this study, our objective was to analyze defensive responses of sorghum against aphid and identify aphid resistance genes in sorghum. For the experiments, seedlings developed from an aphid resistant germplasm line (PI 550607) were divided into two groups, then, one group was infested with greenbug ((Schizaphis graminum Rondani) and the other group was used as control (un-infested). In addition, seedlings of sorghum cultivar Tx 7000, a susceptible genotype, prepared under the same conditions, were used as a genetic control. Those plant samples were used to develop transcriptional profiles using the microarray method, from which 26.1% of the 1,761 cDNA sequences spotted on the microarray showed altered expression between two treatments at 4days after infestation. Sequence annotation and molecular analysis revealed that many differentially expressed genes (DEGs) were related to direct host defense or signal transduction pathways, which regulate host defense. In addition to common responsive genes, unique transcripts were identified in response to greenbug infestation specifically. Later, a similar transcriptional profiling was conducted using the RNA-seq method, resulted in the identification of 2,856 DEGs in the resistant line with a comparison between infested and non-infested at 4days and 4,354 DEGs in the resistant genotype compared to the susceptible genotype at 4days. Based on the comparative analysis, the data of RNA-seq provided a support for the results from the microarray study as it was noticed that many of the DEGs are common in both platforms. Analysis of the two differential expression profiles indicate that aphid triggered dynamic defense responses in sorghum plants and sorghum plant defense against aphid is a complex process involving both general defense systems and specific resistance mechanisms. Finally, the results of the study provide new insights into the mechanisms underlying host plant defense against aphids and will help us design better strategies for effectively controlling aphid pest.

The Effect of Concentration and Frequency of Neem Leaf Extract on Aphid Attacks on Chili Plants

Aphids that attack red pepper plants cause yield loss. Applying neem leaf extract in the form of concentration and frequency of yield losses can be avoided. Neem leaf extract contains secondary metabolite compounds that can function as vegetable insecticides to suppress the level of aphid attacks on chili plants. Saponins, meliantriol, and azadirachtin have been known as active ingredients that act as insecticides with different mechanisms of action against aphids, such as saponins as stomach poisons and contact poisons, meliantriol as a repellent (repellent/repellent), and azadirachtin as an inhibitor of ecdysone hormones (hormones that play a role in the process of metamorphosis or molting or exoskeleton of aphids). The study aimed to determine the effect of concentration and frequency of neem leaf extract on the incidence and severity of chili aphid attacks as well as plant development. The proposed solution to overcome aphid attacks is administering neem leaf extract to red chili plants. The method uses a randomized trial design of factorial groups with two factors. The first factor is the concentration of neem leaf extract which consists of four levels, namely: S0 = 0% (100 ml of water or without neem leaf extract), S1 = 10% (10 ml of neem leaf extract + 90 ml of water), S2 = 30% (30 ml of neem leaf extract + 70 ml of water), and S3 = 50% (50 ml of neem leaf extract + 50 ml of water). The second factor is the frequency of giving neem leaf extract, which consists of four levels: M1 = age 8 HSPT, M2 = age 16 HSPT, M3 = age 24 HSPT, and M4 = age 32 HSPT. The findings of this study are that the frequency of giving neem leaf extract three times showed a real effect on the severity of aphid attacks at the age of 44 days after transplanting, and giving a 10% extract had a real effect on height, leaf area, number of flowers, header dry bobobt, and dry weight of chili plant roots. The results of this study conclude that the administration of neem leaf extract can suppress the severity of the attack of red chili plant aphids.

Small volatile lipophilic molecules induced belowground by aphid attack elicit a defensive response in neighbouring un-infested plants.

In pioneering studies on plant-aphid interactions, we have observed that Vicia faba plants infested by aphids can transmit signals via the rhizosphere that induce aboveground defence in intact, neighbouring plants. The aphid parasitoid Aphidius ervi is significantly attracted towards intact broad bean plants grown in a hydroponic solution previously harbouring Acyrtosiphon pisum-infested plants. To identify the rhizosphere signal(s) possibly mediating this belowground plant-plant communication, root exudates were collected using Solid-Phase Extraction (SPE) from 10-day old A. pisum-infested and un-infested Vicia faba plants hydroponically grown. To verify the ability of these root exudates to trigger defence mechanisms against the aphids we added them to V. fabae plants grown in hydroponic solution, and tested these plants in the wind-tunnel bioassay to assess their attractiveness towards the aphids' parasitoids A. ervi. We identified three small volatile lipophilic molecules as plant defence elicitors: 1-octen-3-ol, sulcatone and sulcatol, in SPE extracts of A. pisum-infested broad bean plants. In wind tunnel assays, we recorded a significant increase in the attractiveness towards A. ervi of V. faba plants grown in hydroponic solution treated with these compounds, compared to plants grown in hydroponic treated with ethanol (control). Both 1-octen-3-ol and sulcatol have asymmetrically substituted carbon atoms at positions 3 and 2, respectively. Hence, we tested both their enantiomers alone or in mixture. We highlighted a synergistic effect on the level of attractiveness towards the parasitoid when testing the three compounds together in respect to the response recorded against them singly tested. These behavioural responses were supported by the characterization of headspace volatiles released by tested plants. These results shed new light on the mechanisms underlying plant-plant communication belowground and prompt the use of bio-derived semiochemicals for a sustainable protection of agricultural crops.

Potential effect of intercropping in the control of weeds, diseases, and pests in a wheat-faba bean system

Intercropping has proved to be a promising alternative in the biological control of biotic factors by reducing the excessive use of plant protection products that are harmful to the environment and human health. In this study, aimed to examinate the effect of intercropping systems on diseases, weeds and pests control in organic field experiments in Western Morocco. Two field experiments were conducted during 2017-2018 and 2018-2019. Three cropping regimes (monocropped wheat, monocropped faba bean, and intercropped wheat-faba bean) and three nitrogen levels N0 (0 kg N ha-1), N1 (50 kg N ha-1), and N2 (100 kg N ha-1) were evaluated. Compared with monocropping, intercropping (N0 level) reduced the incidence of stripe rust by 71–120 % and severity by 244–337 % in 1st and 2nd experiments respectively. In addition, the incidence of septoria was reduced by 236 % and severity by 276 %. Obviously, the intercrops significantly decreased the total weed biomass by more than 40 % in both experiments. Black aphid populations in faba bean were reduced by 80 %. In contrast, the nitrogen fertilizer increased the attack of diseases and black aphids. It is concluded that wheat-faba bean intercrops can be used as a method of reduction of inputs, reduction of environmental impacts of crops, and stability in the face of biotic factors.

Arbuscular mycorrhizal fungus changes alfalfa (Medicago sativa) metabolites in response to leaf spot (Phoma medicaginis) infection, with subsequent effects on pea aphid (Acyrthosiphon pisum) behavior.

Plant disease occurs simultaneously with insect attack. Arbuscular mycorrhizal fungi (AMF) modify plant biotic stress response. Arbuscular mycorrhizal fungi and pathogens may modify plant volatile organic compound (VOC) production and insect behavior. Nevertheless, such effects are rarely studied, particularly for mesocosms where component organisms interact with each other. Plant-mediated effects of leaf pathogen (Phoma medicaginis) infection on aphid (Acyrthosiphon pisum) infestation, and role of AMF (Rhizophagus intraradices) in modifying these interactions were elucidated in a glasshouse experiment. We evaluated alfalfa disease occurrence, photosynthesis, phytohormones, trypsin inhibitor (TI) and total phenol response to pathogen and aphid attack, with or without AMF, and aphid behavior towards VOCs from AMF inoculated and non-mycorrhizal alfalfa, with or without pathogen infection. AM fungus enhanced alfalfa resistance to pathogen and aphid infestation. Plant biomass, root : shoot ratio, net photosynthetic rate, transpiration rate, stomatal conductance, salicylic acid, and TI were significantly increased in AM-inoculated alfalfa. Arbuscular mycorrhizal fungi and pathogen significantly changed alfalfa VOCs. Aphids preferred VOCs of AM-inoculated and nonpathogen-infected to nonmycorrhizal and pathogen-infected alfalfa. We propose that AMF alter plant response to multiple biotic stresses in ways both beneficial and harmful to the plant host, providing a basis for strategies to manage pathogens and herbivore pests.

Bioelectricity in Plants: From So Simple a Beginning

Bioelectricity in Plants: From So Simple a Beginning

Interactive potential effects of moringa leaf extracts and plant growth promoting rhizobacteria against aphid attack on a newly developed wheat variety

Interactive potential effects of moringa leaf extracts and plant growth promoting rhizobacteria against aphid attack on a newly developed wheat variety

The phloem lectin PP2-A1 enhances aphid resistance by affecting aphid behavior and maintaining ROS homeostasis in cucumber plants

Aphid (Aphis gossypii Glover) attack frequently results in a significant loss of output and deterioration of fruit quality in cucumber (Cucumis sativus L.). Phloem protein 2 (PP2) is conserved as a phloem lectin in plants, and few studies have been conducted on the regulatory mechanism of PP2. Based on our previous study of CsPP2-A1 in cucumber, to further investigate the biological function of CsPP2-A1, we compared the changes of selectivity, non-selectivity, colonization, reproductions of aphids, and the phenotype in wild type (WT), CsPP2-A1 overexpressing (CsPP2-A1-OE), and CsPP2-A1 interfering (CsPP2-A1-RNAi) cucumber plants after inoculation with aphids. We found that CsPP2-A1-OE cucumber plants generated resistance to aphids. The aphid colonization rate and number of reproductions of CsPP2-A1-OE cucumber plants were significantly lower than that of WT and CsPP2-A1-RNAi cucumber plants. Through Pearson's correlation and principal component analysis (PCA), it was found that CsPP2-A1 played a crucial role in the balance of reactive oxygen species (ROS) in plants. Overexpression of the CsPP2-A1 resulted in increased levels of antioxidant enzyme, eliminating ROS and preventing the damage by ROS in cucumber. Furthermore, nutritional imbalance for aphids and content of secondary metabolites were increased in overexpressed CsPP2-A1 cucumber plants, and thus preventing aphid attack. These together may improve cucumber resistance against aphids and the mechanism of CsPP2-A1 defense against aphids was preliminarily explored.

Molecular module of CmMYB15-like-Cm4CL2 regulating lignin biosynthesis of chrysanthemum (Chrysanthemum morifolium) in response to aphid (Macrosiphoniella sanborni) feeding.

Lignin is a major component of plant cell walls and a conserved basic defense mechanism in higher plants deposited in response to aphid infection. However, the molecular mechanisms of lignin biosynthesis in response to aphid infection and the effect of lignin on aphid feeding behavior remain unclear. We report that 4-Coumarate:coenzyme A ligase 2 (Cm4CL2), a gene encoding a key enzyme in the lignin biosynthesis pathway, is induced by aphid feeding, resulting in lignin deposition and reduced aphid attack. Upstream regulator analysis showed that the expression of Cm4CL2 in response to aphid feeding was directly upregulated by CmMYB15-like, an SG2-type R2R3-MYB transcription factor. CmMYB15-like binds directly to the AC cis-element in the promoter region of Cm4CL2. Genetic validation demonstrated that CmMYB15-like was induced by aphid infection and contributed to lignin deposition and cell wall thickening, which consequently enhanced aphid resistance in a Cm4CL2-dependent manner. This study is the first to show that the CmMYB15-like-Cm4CL2 module regulates lignin biosynthesis in response to aphid feeding.