Synergistic Effect of Beauveria bassiana and Trichoderma asperellum to Induce Maize (Zea mays L.) Defense against the Asian Corn Borer, Ostrinia furnacalis (Lepidoptera, Crambidae) and Larval Immune Response

Abstract

Ostrinia furnacalis, is the major pest of maize causing significant yield losses. So far, many approaches have been used to increase the virulence of entomopathogenic fungal isolates. The current study is an attempt to estimate synergistic effect of Beauveria bassiana and Trichoderma asperellum in order to explore larval immune response through RNA sequencing and differentially expression analysis. In vivo synergism was examined in seven proportions (B. bassiana: T. asperellum = 1:1, 1:2, 1:3, 1:4, 4:1, 3:1, 2:1) and in the in vitro case, two inoculation methods were applied: seed coating and soil drenching. Results revealed significant decrease in plant damage and high larval mortality in fungal treatments. Fungal isolates mediated the plant defense by increasing proline, superoxide dismutase (SOD), peroxidase (POD), polyphenol oxidase (PPO) and protease activities. Seed coating method was proved to be the most effective in case of maize endophytic colonization. In total, 59 immune-related differentially expressed genes DEGs were identified including, cytochrome P450, heat shock protein, ABC transporter, cadherin, peptidoglycan recognition protein (PGRP), cuticlular protein, etc. Further, transcriptomic response was confirmed by qRT-PCR. Our results concluded that, coculture of B. bassiana and T. asperellum has the synergistic potential to suppress the immune response of O. furnacalis and can be used as sustainable approach to induce plant resistance through activation of defense-related enzymes.

Myco-Synergism Boosts Herbivory-Induced Maize Defense by Triggering Antioxidants and Phytohormone Signaling

“…has also been found with some functions against plant insects in different ways. More interestingly, in our previous study, we proved that T. asperellum and Beauveria bassiana are great entomopathogenic against O. furnacalis in maize (Batool et al, 2020). The plant herbivory response is a dynamic process that temporally and spatially regulates proteins, metabolic profiles, and transcript patterns (Ehlting et al, 2008;Barah and Bones, 2015).…”

“…The B. bassiana OFDH1-5 (ACCC32726) sourced through Jilin Academy of Agricultural Sciences, Gongzhuling, China and the T. asperellum GDFS1009 (CGMCC NO. 9512) obtained from the School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China, were selected for this study based on the previous results ( Batool et al, 2020 ). Fungal strains were grown and conidial suspensions of B. bassiana OFDH1-5 (1 × 10 9 ), T. asperellum GDFS1009 (1 × 10 9 ), and combined suspension of B. bassiana OFDH1-5 + T. asperellum GDFS1009 (5.9 × 10 5 + 8.4 × 10 8 ) in 1:1 were prepared as described by Batool et al (2020) .…”

“…Maize plants undergo several challenges during their growth, including pathogenic infections, environmental stresses, and insect attacks ( Batool et al, 2020 ). Asian corn borer, Ostrinia furnacalis (Guenée), is among the most destructive insect pests of maize in Southeast and East Asia, especially China, causing an estimated yield loss of 6–9 million tons annually ( He et al, 2003 ).…”

“…Asian corn borer, Ostrinia furnacalis (Guenée), is among the most destructive insect pests of maize in Southeast and East Asia, especially China, causing an estimated yield loss of 6–9 million tons annually ( He et al, 2003 ). Based on the importance of sustainable and eco-friendly agricultural practices ( Guo et al, 2019 ), O. furnacalis control strategies have been shifted toward the application of biological control agents rather than harmful chemical pesticides ( Mitchell et al, 2016 ; Batool et al, 2020 ). The Trichoderma spp.…”

“…JA-induced signaling is primarily regulated upon insect feeding, whereas salicylic acid regulates the response to phloem-feeding insects ( Tzin et al, 2015 ; Heidel-Fischer et al, 2018 ). Herbivory-induced defensive enzymes, including enzymatic [superoxide dismutase (SOD), peroxidase (POD), polyphenol oxidase (PPO), and protease] and non-enzymatic (proline) antioxidants in maize plants, help to develop resistance against a corn borer and are responsible for the regulation of plant defense mechanism through the production of secondary metabolites and reactive oxygen species (ROS) scavenging ( Batool et al, 2020 ). Trichoderma is also capable of stimulating an induced systemic resistance (ISR) plant defense response against aphids, caterpillars, and nematodes, modulated by crosstalk between SA and JA ( Di Lelio et al, 2021 ).…”