Plant allelochemicals affect tolerance of polyphagous lepidopteran pest Helicoverpa armigera (Hübner) against insecticides.

Cotton bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), is a polyphagous lepidopteran pest distributed worldwide with a broad spectrum of host plants. However, the mechanism of H. armigera adaptation to various insecticides and defensive allelochemicals in its host plants is not fully understood. Therefore, this study examined the influence of consumption of plant allelochemicals on larval tolerance to methomyl and chlorpyrifos insecticides in H. armigera and its possible mechanism. Twelve plant allelochemicals were screened to evaluate their effects on larval sensitivity to methomyl. Of which flavone, coumarin, DIMBOA (2,4-Dihydroxy-7-methoxy-1,4-benzoxazin-3-one) and visnagin significantly reduced larval sensitivity to methomyl. Application of cytochrome P450 inhibitor piperonyl butoxide (PBO) significantly increased the mortality of methomyl-treated larvae. In contrast, PBO addition significantly decreased the mortality of chlorpyrifos-treated larvae. Moreover, allelochemical consumption enhanced the activities of glutathione S-transferase, carboxylesterase, cytochrome P450 and acetylcholinesterase in the midgut and fat body. The qRT-PCR analysis confirms that P450 genes, CYP6B2, CYP6B6 and CYP6B7 were induced by the four allelochemicals in the midguts and the fat bodies. In conclusion, the generalist H. armigera can take benefit of plant allelochemicals from its host plants to elaborate its defense against insecticides.

Bioactivation of aflatoxin B1 by a cytochrome P450, CYP6AE19 induced by plant signaling methyl jasmonate in Helicoverpa armigra (Hübner).

Herbivore attack leads to enhanced production of defensive compounds to mount anti-herbivore defense in plants via activation of the jasmonate signaling pathway. On the other hand, some herbivores can eavesdrop on plants defense signaling and up-regulate their cytochrome P450 genes to increase detoxification of defensive compounds. However, the ecological risk of eavesdropping on plant defense signaling is largely unknown. In this study, we examined the induction of cytochrome P450s by methyl jasmonate (MeJA) and its consequence on the toxicity of aflatoxin B1 (AFB1) to Helicoverpa armigra larvae. The results show that MeJA applications either in a diet or volatile exposure enhanced the toxicity of AFB1 to the larvae. RNA sequences analysis revealed that cytochrome P450 CYP6AE19 was highly induced when MeJA was applied with AFB1. In addition, HaGST encoding glutathione-S-transferase that mainly transforms aflatoxin B1 exo-8,9-epoxide to aflatoxin B1 exo-8,9-glutathione was also induced. RNA interference of CYP6AE19 via injecting a double-stranded RNA decreased mortality of larvae exposed to AFB1; while injecting a double-stranded RNA of HaGST increased larval mortality. Furthermore, a protein model was generated and a subsequent docking simulation for AFB1 suggests the bioactivation as a major mechanism of AFB1. This study provides evidence that MeJA increased larval mortality of H. armigera via induction of CYP6AE19 that can bioactivate AFB1.

Albocycline-type Macrolides with Antibacterial Activities from Streptomyces sp. 4205.

The actinomycete genus Streptomyces is characterized by producing bioactive secondary metabolites, including antibiotics. In this study, chemical and biological investigations were carried out on Streptomyces strain 4205 isolated from the paddy soil, leading to the identification and characterization of 10 albocycline-type macrolides, among which 4 compounds were new, namely albocyclines A-D (1-4). The structures of 1-10 were identified according to the 1D- and 2D-NMR spectroscopic data. Furthermore, compounds 1-10 were evaluated for antimicrobial activity. Compounds 5-7 displayed antimicrobial activities against Candidaalbicans ATCC 90028 with the same MIC value of 10.0 mg/mL and the IC50 values of 1.5, 1.0, and 1.0 mg/mL, respectively. Thus, the research on Streptomyces sp. is of vital significance for developing new antibiotic agents.

Ratoon rice generated from primed parent plants exhibit enhanced herbivore resistance.

Rice ratooning is practiced in many rice-growing countries for achieving increased rice production with limited labour input. Here, we report that attack by insect herbivores, or treatment with a defense signaling compound in parent plants, can prime anti-herbivore defense responses in subsequent ratoon plants. We compared the defense responses of rice ratoons generated from parent plants that had been either infested by Cnaphalocrocis medinalis (rice leaffolder, LF) caterpillars or treated with methyl jasmonate (MeJA) during vegetative growth, with ratoons generated from control parent plants. Ratoon plants generated from parents receiving prior LF infestation or MeJA treatment exhibited higher jasmonic acid (JA) levels, as well as elevated levels of transcripts of defense-related genes associated with JA signaling. In addition, elevated activities of peroxidase, polyphenol oxidase and trypsin protease inhibitor were observed, as well as enhanced resistance towards subsequent LF infestation. Pre-priming of ratoon defense responses was significantly reduced in plants where expression of OsAOS (allene oxide synthase, involved in JA biosynthesis) or OsCOI1 (CORONATINE INSENSITIVE1, involved in JA perception) was inhibited by RNA interference. Our results indicate that herbivore exposure or MeJA treatment in rice parent plants enhances anti-herbivore resistance in subsequently generated ratoons through priming of JA-mediated defenses.

Expression analysis of two P450 monooxygenase genes of the tobacco cutworm moth (Spodoptera litura) at different developmental stages and in response to plant allelochemicals.

Cytochrome P450 monooxygenases (P450s) of insects are known to be involved in the metabolism or detoxification of plant allelochemicals and insecticides. Spodoptera litura (Lepidoptera, Noctuidae) is a polyphagous moth responsible for severe yield losses in many crops. In this study, two full-length P450 genes, CYP6B48 and CYP6B58, were cloned from S. litura. The cDNA sequences encode proteins with 503 and 504 amino acids, respectively. Phylogenetic analysis revealed that CYP6B48 and CYP6B58 belong to the CYP6B subfamily of P450s. Quantitative real-time PCR analyses showed that CYP6B48 and CYP6B58 were expressed only at larval stage, but not at pupal and adult stages. The highest levels of transcripts were found in the midguts and fat bodies of the larvae. No expression was detected in the ovary or hemolymph. Feeding with diets containing cinnamic acid, quercetin, or coumarin did not affect expression of CYP6B48. In contrast, diet supplemented with xanthotoxin dramatically increased the levels of CYP6B48 transcript in the midgut and fat bodies. Larvae fed with flavone had high levels of transcript of CYP6B48 in the midgut, whereas only slightly elevated levels were found in the fat bodies. Effects of the tested allelochemicals on CYP6B58 expression were minor. Hence, our findings show that S. litura responds to specific allelochemicals such as xanthotoxin with the accumulation of CYP6B48 transcripts, suggesting that specific signals in the food control the insect's ability to convert toxic allelochemicals to less harmful forms at the transcriptional level.

Identification and Characterization of CYP9A40 from the Tobacco Cutworm Moth (Spodoptera litura), a Cytochrome P450 Gene Induced by Plant Allelochemicals and Insecticides.

Cytochrome P450 monooxygenases (P450s) of insects play crucial roles in the metabolism of endogenous and dietary compounds. Tobacco cutworm moth (Spodoptera litura), an important agricultural pest, causes severe yield losses in many crops. In this study, we identified CYP9A40, a novel P450 gene of S. litura, and investigated its expression profile and potential role in detoxification of plant allelochemicals and insecticides. The cDNA contains an open reading frame encoding 529 amino acid residues. CYP9A40 transcripts were found to be accumulated during various development stages of S. litura and were highest in fifth and sixth instar larvae. CYP9A40 was mainly expressed in the midgut and fat body. Larval consumption of xenobiotics, namely plant allelochemicals (quercetin and cinnamic acid) and insecticides (deltamethrin and methoxyfenozide) induced accumulation of CYP9A40 transcripts in the midgut and fat body. Injection of dsCYP9A40 (silencing of CYP9A40 by RNA interference) significantly increased the susceptibility of S. litura larvae to the tested plant allelochemicals and insecticides. These results indicate that CYP9A40 expression in S. litura is related to consumption of xenobiotics and suggest that CYP9A40 is involved in detoxification of these compounds.

Control of Panama disease of banana by rotating and intercropping with Chinese chive (Allium tuberosum Rottler): role of plant volatiles.

Intercropping and rotating banana (Musa spp.) with Chinese chive (Allium tuberosum Rottler) has been used as an effective method to control Panama disease (Fusarium wilt) of banana in South China. However, the underlying mechanism is unknown. In this study, we used aqueous leachates and volatiles from Chinese chive to evaluate their antimicrobial activity on Fusarium oxysporum f. sp. cubense race 4 (FOC), the causal agent of Panama disease in banana, and identified the antifungal compounds. Both leaf and root leachates of Chinese chive displayed strong inhibition against FOC, but the concentrated leachates showed lower inhibition than the original leachates. In a sealed system volatiles emitted from the leaves and roots of Chinese chive inhibited mycelial growth of FOC. Volatile compounds emitted from the intact growing roots mimicking natural environment inhibited spore germination of FOC. We identified five volatiles including 2-methyl-2-pentenal and four organosulfur compounds (dimethyl trisulfide, dimethyl disulfide, dipropyl disulfide, and dipropyl trisulfide) from the leaves and roots of Chinese chive. All these compounds exhibited inhibitory effects on FOC, but 2-methyl-2-pentenal and dimethyl trisulfide showed stronger inhibition than the other three compounds. 2-Methyl-2-pentenal at 50-100 µl/l completely inhibited the mycelial growth of FOC. Our results demonstrate that antifungal volatiles released from Chinese chive help control Panama disease in banana. We conclude that intercropping and rotating banana with Chinese chive can control Panama disease and increase cropland biodiversity.

Priming of anti-herbivore defense in tomato by arbuscular mycorrhizal fungus and involvement of the jasmonate pathway.

Mycorrhizas play a vital role in soil fertility, plant nutrition, and resistance to environmental stresses. However, mycorrhizal effects on plant resistance to herbivorous insects and the related mechanisms are poorly understood. This study evaluated effects of root colonization of tomato (Solanum lycopersicum Mill.) by arbuscular mycorrhizal fungi (AMF) Glomus mosseae on plant defense responses against a chewing caterpillar Helicoverpa arimigera. Mycorrhizal inoculation negatively affected larval performance. Real time RT-PCR analyses showed that mycorrhizal inoculation itself did not induce transcripts of most genes tested. However, insect feeding on AMF pre-inoculated plants resulted in much stronger defense response induction of four defense-related genes LOXD, AOC, PI-I, and PI-II in the leaves of tomato plants relative to non-inoculated plants. Four tomato genotypes: a wild-type (WT) plant, a jasmonic acid (JA) biosynthesis mutant (spr2), a JA-signaling perception mutant (jai1), and a JA-overexpressing 35S::PS plant were used to determine the role of the JA pathway in AMF-primed defense. Insect feeding on mycorrhizal 35S::PS plants led to higher induction of defense-related genes relative to WT plants. However, insect feeding on mycorrhizal spr2 and jai1 mutant plants did not induce transcripts of these genes. Bioassays showed that mycorrhizal inoculation on spr2 and jai1 mutants did not change plant resistance against H. arimigera. These results indicates that mycorrhizal colonization could prime systemic defense responses in tomato upon herbivore attack, and that the JA pathway is involved in defense priming by AMF.

[Research advances in histone modification-regulated plant stress memory and defense priming.] / ç»„è›‹ç™½ä¿®é¥°è°ƒæŽ§æ¤ç‰©å¯¹èƒè¿«çš„è®°å¿†ä¸Žè­¦å¤‡æŠ—æ€§çš„ç ”ç©¶è¿›å±•.

Plants, grown in the immobile soils, have evolved various strategies in response to environmental stresses, including the "stress memory" and "defense priming" mechanisms. The environmental stresses cannot immediately change the DNA base sequence in plants in the short-term. Therefore, epigenetic inheritance is a key mechanism for stress memory and defense priming. In particular, histone modification is considered to be the most important mechanism, which offers the possibility of stress memory. We summarized research advances in plant histone modifications involved in stress memory and defense priming under biotic and abiotic stresses, and proposed pro-blems in the field and the focus and directions in the future research. In-depth understanding of the relationship between histone modification and environmental stresses would facilitate the quick adaptation of plants to harsh environments, and provide theoretical and technical guidance for plant phenotype shaping, organ regeneration, and crop genetic improvement.

Induction of DIMBOA accumulation and systemic defense responses as a mechanism of enhanced resistance of mycorrhizal corn (Zea mays L.) to sheath blight.

Arbuscular mycorrhizas are the most important symbioses in terrestrial ecosystems and they enhance the plant defense against numerous soil-borne pathogenic fungi and nematodes. Two corn (Zea mays) varieties, Gaoyou-115 that is susceptible to sheath blight disease caused by Rhizoctonia solani and Yuenong-9 that is resistant, were used for mycorrhizal inoculation in this study. Pre-inoculation of susceptible Gaoyou-115 with arbuscular mycorrhizal fungus (AMF) Glomus mosseae significantly reduced the disease incidence and disease severity of sheath blight of corn. HPLC analysis showed that AMF inoculation led to significant increase in 2,4-dihydroxy-7-methoxy-2 H-1,4-benzoxazin-3(4 H)-one (DIMBOA) accumulation in the roots of both corn varieties and in leaves of resistant Yuenong-9. R. solani inoculation alone did not result in accumulation of DIMBOA in both roots and leaves of the two corn varieties. Our previous study showed that DIMBOA strongly inhibited mycelial growth of R. solani in vitro. Real-time PCR analysis showed that mycorrhizal inoculation itself did not affect the transcripts of most genes tested. However, pre-inoculation with G. mosseae induced strong responses of three defense-related genes PR2a, PAL, and AOS, as well as BX9, one of the key genes in DIMBOA biosynthesis pathway, in the leaves of corn plants of both Yuenong-9 and Gaoyou-115 after the pathogen attack. Induction of defense responses in pre-inoculated plants was much higher and quicker than that in non-inoculated plants upon R. solani infection. These results indicate that induction of accumulation of DIMBOA, an important phytoalexin in corn, and systemic defense responses by AMF, plays a vital role in enhanced disease resistance of mycorrhizal plants of corn against sheath blight. This study also suggests that priming is an important mechanism in mycorrhiza-induced resistance.

Seed priming with calcium chloride enhances wheat resistance against wheat aphid Schizaphis graminum Rondani.

BACKGROUND: Calcium is an essential macronutrient for plant growth. Although it has been shown that exogenous Ca application can increase plant resistance to abiotic stress, little is known about its potential to enhance plant tolerance to biotic stress. Here, we investigated whether pretreatment of wheat (Triticum aestivum L.) seeds with calcium chloride (CaCl2 ) improves plant resistance against wheat aphid (Schizaphis graminum Rondani). The developmental time, population size, feeding behavior of aphids on plants grown from CaCl2 - and water-pretreated seeds, and plant defense responses to aphid attack were investigated. RESULTS: Seed pretreatment with CaCl2 extended aphid development time and reduced aphid population size and feeding efficiency. In addition, the pretreatment significantly increased the concentration of Ca2+ in wheat leaves, and upregulated expression levels of TaCaM genes and callose synthase genes (TaGSL2, TaGSL8, TaGSL10, TaGSL12, TaGSL19, TaGSL22 and TaGSL23). Callose concentration in the leaves of plants grown from CaCl2 -pretreated seeds increased significantly upon aphid attack. Further, callose deposition was observed mainly in the phloem. CONCLUSION: These results suggest that seed pretreatment with CaCl2 primes the plant response against wheat aphid attack, leading to modulation of callose deposition in the phloem in response to aphid attack. © 2021 Society of Chemical Industry.

The KNRL nuclear receptor controls hydrolase-mediated vitellin breakdown during embryogenesis in the brown planthopper, Nilaparvata lugens.

Vitellin (Vn) homeostasis is central to the fecundity of oviparous insects. Most studies have focused on the synthesis and transportation of Vn as a building block for developing eggs during vitellogenesis; however, less is known about how the utilization of this nutrient reserve affects embryonic development. Here, we show that the single ortholog of the knirps and knirps-like nuclear receptors, KNRL, negatively regulates Vn breakdown by suppressing the expression of hydrolase genes in the brown planthopper, Nilaparvata lugens. KNRL was highly expressed in the ovary of adult females, and knockdown of KNRL by RNA interference resulted in the acceleration of Vn breakdown and the inhibition of embryonic development. Transcriptome sequencing analysis revealed that numerous hydrolase genes, including cathepsins and trypsins were up-regulated after KNRL knockdown. At least eight of the nine significantly enriched Gene Ontology terms for the up-regulated genes were in proteolysis-related categories. The expression levels of five selected trypsin genes and the enzymatic activities of trypsin in the embryos were significantly increased after KNRL knockdown. Moreover, trypsin injection prolonged egg duration, delayed embryonic development, accelerated Vn breakdown and severely reduced egg hatchability, a pattern similar to that observed in KNRL-silenced N. lugens. These observations suggest that KNRL controls Vn breakdown in embryos via the transcriptional inhibition of hydrolases. Generally, this study provides a foundation for understanding how embryo nutrient reserves are mobilized during embryogenesis and identifies several genes and pathways that may prove valuable targets for pest control.

Activiation of the nitric oxide cycle by citrulline and arginine restores susceptibility of resistant brown planthoppers to the insecticide imidacloprid.

Pest management, which is critical for global crop productivity, is hampered by rapidly evolving insecticide resistance in insect pests. The ability to manage the development of insecticide resistance is thus vital. Nitric oxide (NO) is a ubiquitous signaling molecule with important functions in a variety of biological processes. Here we show that imidacloprid-resistant brown planthoppers (BPH) are deficient in citrulline and arginine, both of which are involved in NO production, but exogenous citrulline and arginine render resistant BPH vulnerable to imidacloprid. BPH insecticide resistance results from low NO production; exogenous arginine and citrulline augment the NO signaling in BPH, leading to downregulation of CYP6AY1 and CYP6ER1, the cytochrome P450 s that contribute to imidacloprid detoxification, thereby restoring susceptibility. Two amino acids that can be used to restore susceptibility in insecticide-resistant insects are identified, establishing a novel metabolome-based approach for killing insecticide-resistant pests and providing a useful template for managing insecticide resistance.

Ecological significance of induction of broad-substrate cytochrome P450s by natural and synthetic inducers in Helicoverpa zea.

The polyphagous corn earworm Helicoverpa zea relies on cytochrome P450 monooxygenases with broad substrate specificities to cope with the wide diversity of phytochemicals it encounters among its numerous host plants. These enzymes also contribute to the ability of this insect to tolerate toxins from sources other than its hosts, including microbial and synthetic toxins. Although upregulation of xenobiotic-metabolizing P450s in some herbivorous insects is closely linked to host plant toxins, transcriptional and/or post-transcriptional regulation of detoxification in this polyphagous species also appears to be relatively unspecialized. Reverse transcription polymerase chain reaction and metabolic analyses indicate that rare and infrequently encountered phytochemicals, as well as synthetic substances, can enhance metabolic activity in an adaptive fashion against both natural and synthetic toxins.

Enhanced toxicity and induction of cytochrome P450s suggest a cost of "eavesdropping" in a multitrophic interaction.

The inducibility of cytochrome P450 monooxygenases (P450s) and other xenobiotic-metabolizing enzymes is thought to reflect material and energy costs of biosynthesis. Efforts to detect such costs of detoxification enzyme induction, however, have had mixed success. Although they are rarely considered, ecological costs of induction may be a more significant evolutionary constraint on herbivores than material and energy costs. Because some P450-mediated metabolic transformations are bioactivation reactions that increase, rather than reduce, toxicity, maintaining high levels of P450 activity places an organism at risk of greater mortality in the presence of compounds that are bioactivated. We show that P450 inducibility in the generalist moth Helicoverpa zea in response to plant signaling substances, an adaptive response in a ditrophic interaction between herbivore and plant, becomes detrimental in the presence of a third trophic association with a plant pathogen that produces aflatoxin, a toxin that can be bioactivated by P450s. Consumption of plant signaling molecules, such as methyl jasmonate (MeJA) and salicylic acid (SA) enhanced the toxicity of aflatoxin B1 (AFB1) to H. zea that resulted in substantially more damage to larval growth and development. Among the P450 transcripts already cloned from this organism, two in the CYP6B and CYP321A subfamilies are shown to be induced in response to MeJA and SA, suggesting that they may mediate some of the observed bioactivations.

Diterpenoids with herbicidal and antifungal activities from hulls of rice (Oryza sativa).

Diterpenoids are the main secondary metabolites of plants and with a range of biological activities. In the present study, 7 compounds were isolated from the hulls of rice (Oryza sativa L.). Among them, 3 diterpenoids are new namely, 3,20-epoxy-3α-hydroxy- 8,11,13-abietatrie-7-one (1), 4,6-epoxy-3ß-hydroxy-9ß-pimara-7,15-diene (2) and 2-((E)-3- (4-hydroxy-3-methoxyphenyl) allylidene) momilactone A (3). While, 4 terpenoids are known, namely momilactone A (4), momilactone B (5), ent-7-oxo-kaur-15-en-18-oic acid (6) and orizaterpenoid (7). The structures of these diterpenoids were elucidated using 1D and 2D NMR in combination with ESI-MS and HR-EI-MS. Furthermore, all isolated compounds displayed antifungal activities against four crop pathogenic fungi Magnaporthe grisea, Rhizoctonia solani, Blumeria graminearum and Fusarium oxysporum, and phytotoxicity against paddy weed Echinochloa crusgalli. The results suggested that rice could produce plenty of secondary metabolites to defense against weeds and pathogens.

Aflatoxin B1 detoxification by CYP321A1 in Helicoverpa zea.

The polyphagous corn earworm Helicoverpa zea frequently encounters aflatoxins, mycotoxins produced by the pathogens Aspergillus flavus and A. parasiticus, which infect many of this herbivore's host plants. While aflatoxin B1 metabolism by midgut enzymes isolated from fifth instars feeding on control diets was not detected, this compound was metabolized by midgut enzymes isolated from larvae consuming diets supplemented with xanthotoxin, coumarin, or indole-3-carbinol, phytochemicals that are likely to co-occur with aflatoxin in infected host plants. Of the two metabolites generated, the main derivative identified in midguts induced with these chemicals and in reactions containing heterologously expressed CYP321A1 was aflatoxin P1 (AFP1), an O-demethylated product of AFB1. RT-PCR gel blots indicated that the magnitude of CYP321A1 transcript induction by these chemicals is associated with the magnitude of increase in the metabolic activities of induced midgut enzymes (coumarin>xanthotoxin>indole 3-carbinol). These results indicate that induction of P450s, such as CYP321A1, plays an important role in reducing AFB1 toxicity to H. zea. Docking of AFB1 in the molecular models of CYP321A1 and CYP6B8 highlights differences in their proximal catalytic site volumes that allow only CYP321A1 to generate the AFP1 metabolite.

[Plant anti-herbivore defense priming: Concept, mechanisms and application.] / 植物抗虫"防御警备": 概念、机理与应用.

Plant anti-herbivore defense priming refers to the increased readiness of anti-herbivore defense after the initial exposure to a series of biotic or abiotic factors. The primed plants can respond to herbivory more quickly and strongly and thereby show enhanced resistance to insect herbivory. It is a newly recognized strategy of plant defense against insect herbivores. Insect feeding, secretion, oviposition, herbivore-inducible plant volatiles (HIPVs), beneficial microorgani-sms, certain plant nutrient elements, heavy metals and some chemical compounds have been found to be able to prime plant defense. The defense priming is highly efficient, durable, environmental friendly, and even trans-generational. This review summarized current research progress on the plant anti-herbivore defense priming in recent years, and analyzed general characteristics, priming agents and potential mechanisms involved, and proposed the future development and the perspective of practical application in the field. Moreover, the unresolved questions and the research directions in this field were also discussed. Appropriate management of plant defense priming would minimize use of insecticide and serve as an important approach of integrated pest management.

[Colonization with arbuscular mycorrhizal fungus Funneliformis mosseae enhanced the responses of tomato plants to mechanical wounding]. / ä¸›æžèŒæ ¹çœŸèŒæ‘©è¥¿ç®¡æŸ„å›Šéœ‰ä¾µæŸ“å¢žå¼ºç•ªèŒ„å¯¹æœºæ¢°æŸä¼¤çš„å“åº”.

Insect herbivore feeding causes mechanical damage to plants, which can activate plant defense responses. Whether symbiosis with beneficial microorganisms can enhance the responses of plants to mechanical damage is of importance for plant anti-herbivore resistance. In this study, defense responses of tomato (Lycopersicon esculentum) plants to mechanical wounding was investigated after the tomato roots being infected by arbuscular mycorrhizal fungus (AMF) Funneliformis mosseae. The results showed that in response to leaf mechanical wounding, the activities of phenylalanine ammonia-lyase (PAL), superoxide dismutase (SOD), peroxidase (POD), polyphenol oxidase (PPO) and catalase (CAT) in the leaves of tomato pre-inoculated with AMF (FD), as well as transcript levels of genes encoding phenylalanine ammonia lyase (PAL) and ß-1,3-glucanase (PR2) in the leaves and roots were significantly higher in relative to sole mechanical wounding (D), sole mycorrhizal inoculation (F), and control without mechanical wounding and mycorrhizal inoculation (CK). Although the activities of protective enzyme and transcript levels of the two defense-related genes were induced in the plants of sole mechanical wounding (D) and sole mycorrhizal inoculation (F), the induction was faster and stronger in the plants with leaf mechanical wounding and mycorrhizal pre-inoculation (FD). Our findings indicated that arbuscular mycorrhizal colonization could prime quicker and stronger defense responses of tomato plants to mechanical damage.