Exogenously applied melatonin alleviates the damage in cucumber plants caused by Aphis goosypii through altering the insect behavior and inducing host plant resistance

Abstract

BACKGROUND Aphis gossypii Glover is the main pest found in most cucumber‐producing areas. Melatonin (MT) has been widely studied in protecting plants from environmental stresses and pathogens. However, little knowledge is available on the impact of MT on insect resistance. RESULTS The fecundity of aphids on MT‐treated cucumber leaves was inhibited. Interestingly, MT‐treated plants were more attractive to aphids, which would prevent the large‐scale transmission of viruses caused by the random movement of aphids. Meanwhile, MT caused varying degrees of change in enzyme activities related to methylesterified HG degradation, antioxidants, defense systems and membrane lipid peroxidation. Furthermore, transcriptomic analysis showed that MT induced 2360 differentially expressed genes (DEGs) compared with the control before aphid infection. These DEGs mainly were enriched in hormone signal transduction, MAPK signaling pathway, and plant‐pathogen interaction, revealing that MT can help plants acquire inducible resistance and enhance plant immunity. Subsequently, 2397 DEGs were identified after aphid infection. Further analysis showed that MT‐treated plants possessed stronger JA signal, reactive oxygen species stability, and the ability of flavonoid synthesis under aphid infection, while mediating plant growth and sucrose metabolism. CONCLUSION In summary, MT as an environmentally friendly substance mitigated aphid damage to cucumbers by affecting the aphids themselves and enhancing plant resistance. This will facilitate exploring sustainable MT‐based strategies for cucumber aphid control. © 2022 Society of Chemical Industry.

Enhancing the Biological Control of Mite Species Infesting Olive Trees through Application of Predatory Mite Agistemus exsertus Gonzalez (Acari: Stigmaeidae) and Eco‐Friendly Natural Compounds

“…Our results agree with those of Liu et al . (2022), who revealed that MT could inhibit aphid reproduction and mitigate aphid damage to cucumber ( Cucumis sativus L.) plants. Moreover, our results support the previous studies which demonstrated the key role of MT, GB and ALA in controlling bacterial and fungal pathogens (Lavanya and Amruthesh, 2017; Wei et al ., 2018).…”

“…Our findings are in harmony with the recent findings of Liu et al . (2022), who recorded elevated flavonoid content in MT‐treated cucumber plants infested with Aphis gossypii Glove.…”

“…However, very few reports showed the significant inhibitory impacts of MT on phytobacterial pathogens and aphids (Wei et al, 2018;Liu et al, 2022). Liu et al (2022) revealed that MT could mitigate aphid damage caused to cucumber (Cucumis sativus L.).…”

“…Moreover, recent studies reported that the exogenous application of MT could induce the defense systems in plants to improve their tolerance to abiotic stresses, including drought (Hossain et al, 2020;Eisa et al, 2023), salinity (Liang et al, 2015), heat (Shi et al, 2015) and heavy metals (Posmyk et al, 2008). However, very few reports showed the significant inhibitory impacts of MT on phytobacterial pathogens and aphids (Wei et al, 2018;Liu et al, 2022). Liu et al (2022) revealed that MT could mitigate aphid damage caused to cucumber (Cucumis sativus L.).…”

“…Liu et al . (2022) revealed that MT could mitigate aphid damage caused to cucumber ( Cucumis sativus L.).…”