Mycorrhizal Inoculation Enhances Nutrient Absorption and Induces Insect-Resistant Defense of Elymus nutans

Abstract

The majority of terrestrial plants can form symbiotic associations on their roots with arbuscular mycorrhizal fungi (AMF) in the soil to stimulate the growth and nutrient uptake of the host plant and to improve plant resistance to insects and disease. However, the use of AMF for insect control on gramineous forages requires further study. Here, we evaluated the effects of AMF (Funneliformis mosseae) inoculation on the defense against Locusta migratoria attack in Elymus nutans. Inoculation assays showed that mycorrhizal plants had a higher resistance than non-inoculated plants, as evidenced by plants having more plant biomass, a higher nitrogen and phosphorus content, and greater lipoxygenase (LOX) activity. The results of insect damage showed that in addition to a decrease in the enzyme phenylalanine-ammonia-lyase, the activities of other plant defense-related enzymes (including polyphenol oxidase and β-1,3-glucanase) were increased. A key enzyme, LOX, belonging to the jasmonic acid (JA) signaling pathway was notably increased in mycorrhizal treatment. Volatile organic compounds (VOCs) were identified using gas chromatography mass spectrometry and the results showed that several metabolites with insect-resistant properties, including D-Limonene, p-Xylene, 1,3-Diethylbenzene were detected in mycorrhizal plants. These findings suggest that mycorrhizal inoculation has potential applications in insect management on forage grasses and demonstrates that the JA signaling pathway is essential for insect resistance in Elymus nutans.

Effect of arbuscular mycorrhizal fungi on the responses of Ageratina adenophora to Aphis gossypii herbivory

“…berolinensis seedlings compared with nonmycorrhizal seedlings, resulting in a high JA content in plant tissues. The increase in the JA content induces chemical defense in plants, regulates the expression of plant secondary metabolite genes, and promotes the synthesis and accumulation of secondary metabolites, thus reducing herbivore preference, performance and abundance ( Zhang et al., 2022 ). We found that the content of total phenols and flavonoids in A. adenophora was significantly increased after inoculation with AMF ( Figure 5 ).…”

Arbuscular mycorrhizal fungus alleviates anthracnose disease in tea seedlings

“…Arbuscular mycorrhizal fungi (AMF), generally forming a symbiotic relationship with approximately 80% of terrestrial plants, can play a crucial role in the plants to face many biotic and abiotic stresses, such as pests, plant pathogens, drought, waterlogging, low temperature, and salinity ( Begum et al., 2019 ; Devi et al., 2022 ; Sivaprakasam Padmanaban et al., 2022 ; Zhang et al., 2022 ). Previous studies demonstrated the function of AMF in controlling anthracnose disease in many herbaceous plants such as Fragaria×ananassa Duch.…”

Volatile organic compounds shape belowground plant–fungi interactions

“…D-Limonene, p-xylene, and 1,3-diethylbenzene increase in Elymus nutans plants colonized with AMF ( Zhang et al., 2022 ). Under insect attack, 1,3-diethylbenzene and D-limonene can be generated to strengthen plant defenses and repel insects ( Agut et al., 2015 ; Kigathi et al., 2019 ; Mitra et al., 2021 ).…”