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Most, if not all, entomopathogenic fungi have been used as alternative control agents to decrease the insect resistance and harmful effects of the insecticides on the environment.
Among them, Isaria fumosorosea has also shown great potential to control different insect pests. In the present study, we explored the immune response of P. To gain insight into the host-pathogen interaction at the genomic level, five libraries of P. In total, immunity-related genes were identified and grouped into four categories; immune recognition families, toll and Imd pathway, melanization, and antimicrobial peptides AMPs.
The results of differentially expressed immunity-related genes depicted that 15, 13, 53, and 14 up-regulated and 38, 51, 56, and 49 were down-regulated in P. In conclusion, our results demonstrate that I. Insects are surrounded by an environment rich with harmful microorganisms and recurring infections are common in the natural environment. In order to combat these potentially infectious pathogens, insects have evolved various defense systems, including the potent immune system.
Unlike mammals, insects solely rely on innate immune responses for host defense. The innate immune responses are usually comprised of cellular and humoral defense responses. The former is best demonstrated by the action of hemocytes in the phagocytosis Kanost et al.
The invading pathogen is recognized via pattern recognition receptors PRRs Hultmark, leading to the amplification of signal of infection by serine proteases following the activation of signaling pathways Jiang and Kanost, ; Osta et al. Finally, the effector factors are induced in the specific tissues to combat the pathogens.
To counter the defense system of the host, insect pathogenic fungi have also developed their mechanisms. The pathogens use a set of enzymes to breach the cuticle Butt, and also release secondary metabolites, to suppress the immune system of the host, during colonization Vilcinskas et al.
Among these entomopathogenic fungi, on one hand, Metarhizium anisopliae has developed a new technique to evade the immune system of host via masking the cell wall during hemocoel colonization Wang and Leger, , and on the other hand, Isaria fumosorosea releases chitinase, chitosanase, lipase, to physically penetrate the host and suppress its regulatory system, and a beauvericin compound to paralyze the host Hajek and St. Leger, ; Ali et al. Consequently, entomopathogenic fungi have received an increased attention as an environmentally friendly alternative control measure to insecticides for controlling P.
Several strains of fungi have been isolated and used to control various insect pests including P. Of these entomopathogenic fungi, I. Isaria fumosorosea , a well-known entomopathogenic fungi, is distributed worldwide. It was previously known as Paecilomyces fumosoroseus , however, now it has been transferred to Isaria genus Zimmermann, Due to wide host range, it has become a promising biological control agent and its potential as a biological control agent, other than immunity, has been tested to control various insect pests, including Diaphorina citri Avery et al.
Previously, most of the reports on insect immunity preferred model insects, including Drosophila melanogaster Wraight et al. It is only recently that P. Although, a recent report on the immune response of P. However, the changes that occur in response to I.
To gain deep insight into the immunogenetics of P. Additionally, a global survey of the activities of anti-fungal immune defense genes in P. The population of susceptible P. China for five years without exposure to pesticides. The I. The conidia were collected from 10 days old culture and suspended with 0. Healthy P. The samples of 50 surviving larvae were collected from the treatment group and the control group at 12, 18, 24, and 36 h, respectively, forming three pairs of hour post-treatment infection and hours post treatment control.
Different time-points of sampling were selected to observe infection dynamics Abkallo et al. Magnetic beads were used to purify the double strand cDNA and finally, ligation of fragments was carried out with sequencing adaptors. After filtering, the remaining clean reads were mapped to reference gene using Bowtie Langmead et al. Finally, normalization of all data was done as fragments per kilobase of transcript per million fragments mapped FPKM.
The analysis of differential expression was employed by a rigorous algorithm. The false discovery rate FDR methodology was adopted in multiple tests Kim and van de Wiel, for determination of threshold of P -value. The genome database of P.
Total RNA isolation method was same as described earlier. To identify genes involved in P. A total of 11,,, 11,,, 12,,, 11,,46, and 11,, reads were generated from these five libraries 12, 18, 24, 36 h, and control respectively , from which To study the gene expression of P.
The analysis of five libraries was carried out by determining the number of fragments per kb per million FPKM of clean reads. Our results exhibited that, compared to the control, there were 53 15 up-regulated and 38 down-regulated , 64 13 up- and 51 down-regulated , 53 up-regulated and 56 down-regulated , and 63 14 up- and 49 down-regulated immune-related genes that were significantly changed in P.
A Venn diagram analysis showed that only 11 immunity-related DEGs were commonly expressed among all the treatments, whereas 7, 13, 45, and 12 immunity-related DEGs were specifically expressed in 12, 18, 24, and 36 h, respectively Figure 2.
Figure 1. Screening of immunity-related DEGs in response to I. Figure 2. A Venn diagram of differentially expressed immunity-related genes in P. The numbers in each circle show differentially expressed genes in each comparison treatment and the overlapping regions display genes that are commonly expressed among the comparison treatments.
Following GO annotation, the immunity-related genes were classified into 26 different groups belonging to biological process, cellular component, and molecular function categories Figure 3. In the biological process category, the two most enriched groups were the response to stimulus and biological regulation, whereas membrane and regulation of biological process were the top two enriched groups in the cellular component. The number of genes involved in catalytic activity and binding were the dominant groups in the category of molecular function Figure 3.
The top five enriched groups among KEGG categories included infectious diseases viral , signaling molecules and interaction, digestive system, infectious diseases parasitic , and signal transduction Figure 4.
Figure 3. Summary of Gene ontology annotation. Functional classification of immunity- related DEGs at 12, 18, 24, and 36 h post-infection in P. Figure 4. KEGG pathway annotation classification of immunity-related genes in P. The abscissa is the KEGG classification, and the ordinate left is the gene number.
The results exhibited that the trend of expression level for all the selected genes was in consistence to that of RNA-Seq Figure 5. Figure 5. To identify immunity-related genes in response to I.
A number of genes having fold change less than one and those annotated as hypothetical or unknown proteins were not selected. Finally, a good number of immunity-related genes were identified and classified as immune recognition families, toll and Imd signaling pathways, melanization, AMPs, and others Table 3.
Table 3. Summary of immunity-related genes identified in Plutella xylostella genome. The entomopathogenic fungi are recognized as an environmentally friendly tactic for controlling the insect pests. Previously, the entomopathogenic fungi like M. Recently, it has been shown that I. Therefore, considering the importance of I. Recognition of pathogen is the initial step in the defense against invading microbes, eliciting cellular and humoral responses.
Pathogens produce conserved pathogen-associated molecular patterns PAMPs and the host produces pattern-recognition receptors PRRs in response Mogensen, In the present report, 14 PGRPs were identified and most of them were down-regulated after treatment with I.
Previously, it has also been shown that PGRPs were down-regulated after the injection of secondary metabolite destruxin of M. Among PRRs, only the scavenger receptors were up-regulated at all-time points post-infection. Our results are in accordance with a previous report showing that among PRRs, only scavenger receptors were up-regulated in response to destruxin A in D.
Figure 6. Functional classification of immunity- related DEGs in response to I. The Toll pathway is primarily activated by fungi and Gram-positive bacteria while the Gram-negative bacteria triggers the activation of Imd pathway leading to the production of AMPs Aggarwal and Silverman, ; Hetru and Hoffmann, Here, in our study, we found that only spatzle and MyD88 showed differential expression while the other immune genes of toll pathway were not induced after treatment with I.
Of note, Imd pathway was also not induced after the treatment with I. The expression of MyD88 was up-regulated whereas, spatzle showed down-regulated expression after treatment Figure 6 and Table 3. Previously, a similar phenomenon was observed in D. Thus, our results show that I.
Melanization is considered as a vital component of the immune system of insects. It regulates the melanin cascade mediated by prophenoloxidases PPO Taft et al. When a pathogen invades, PPO gets activated and transformed into PO following transformation of phenolic substances into quinone intermediates and ultimately killing pathogens. Here, only three PPO were found after the treatment of P. Serine proteases represent a very large group of enzymes in almost all organisms and are involved in various biological processes Ross et al.
The structure of serine proteases consists of His, Asp, and Ser amino acid residues forming a catalytic triad Perona and Craik, Generally, serine proteases are inactive pro-enzymes and need proteolytic cleavage for activation Ross et al.
It has been reported that the serine proteases showed same up- and down-regulated expression in P. Serpins, a super-family of proteins, are found in nearly all organisms Gettins,
Revista de la Sociedad Entomológica Argentina
We'd like to understand how you use our websites in order to improve them. Register your interest. Twelve entomopathogenic fungi were screened for controlling diamondback moth Plutella xylostella L. None had any significant ovicidal effect. Isaria fumosorosea CKPF showed the best efficacy in controlling the 2 nd instar larvae. Both tests revealed that I.
Isaria fumosorosea for pest insect control in vegetables (Final result)
Culture media selection for mass production of Isaria fumosorosea and Isaria farinosa. This work investigated the production of the fungi Isaria fumosorosea and Isaria farinosa in biphasic fermentation using agro-industrial products and residues. Combinations of natural liquid substrates, alternative to the complete medium and potato dextrose medium, were evaluated. In solid-state fermentation, the best conidia production was achieved with the soybean meal and broken corn for I.