Translation Initiation Factor eIF4E Positively Modulates Conidiogenesis, Appressorium Formation, Host Invasion and Stress Homeostasis in the Filamentous Fungi Magnaporthe oryzae

Abstract

Translation initiation factor eIF4E generally mediates the recognition of the 5’cap structure of mRNA during the recruitment of the ribosomes to capped mRNA. Although the eIF4E has been shown to regulate stress response in Schizosaccharomyces pombe positively, there is no direct experimental evidence for the contributions of eIF4E to both physiological and pathogenic development of filamentous fungi. We generated Magnaporthe oryzae eIF4E (MoeIF4E3) gene deletion strains using homologous recombination strategies. Phenotypic and biochemical analyses of MoeIF4E3 defective strains showed that the deletion of MoeIF4E3 triggered a significant reduction in growth and conidiogenesis. We also showed that disruption of MoeIF4E3 partially impaired conidia germination, appressorium integrity and attenuated the pathogenicity of ΔMoeif4e3 strains. In summary, this study provides experimental insights into the contributions of the eIF4E3 to the development of filamentous fungi. Additionally, these observations underscored the need for a comprehensive evaluation of the translational regulatory machinery in phytopathogenic fungi during pathogen-host interaction progression.

AGC/AKT Protein Kinase SCH9 Is Critical to Pathogenic Development and Overwintering Survival in Magnaporthe oryzae

“…After observing the sporulation defect in MoSch9 deleted strains, the virulence efficacy of hyphae and asexual spores produced by ΔMoSch9 was investigated. As previously described [ 36 , 50 ], when 7 day old barley and 21 day old susceptible rice leaves were inoculated with mycelial plugs of wild type and mutant strains, MoSch9 deleted strains (ΔMosch9-33 and ΔMosch9-41) showed no lesion on intact and injured leaves of both barley and rice ( Figure 3 A,B). This indicates that deletion of MoSch9 completely abolished the hyphal mediated pathogenesis of M. oryzae .…”

“…Hyphal-mediated appressorium-like structures and appressorium of M. oryzae are the basic infectious structures responsible for the pathogen’s hyphal and spore-mediated blast infection, respectively, in the host plant [ 36 , 51 , 52 ]. Therefore, to identify the possible reasons that account for attenuation in the virulence of ΔMoSch9 strains, the formation of hyphal-mediated appressorium-like structures and their penetration capability was assessed by inoculating the mycelia of wild-type and ΔMoSch9 strains on barley leaves and hydrophobic coverslips.…”

“…For protoplast preparation, RNA isolation, and gDNA extraction, individual strains were cultured in liquid CM and incubated in a rotatory shaker at a speed of 110 rpm at 25 °C for 3–4 days. For normal fungal growth, storage, and conidiation, complete media and rice bran media (RBM pH: 6.0–6.5) were used following the previously described protocol for media preparation, growth, and storage [ 36 ]. For conidiogenesis, respective strains were inoculated on RBM plates and were incubated for 7 days at 25 °C in the dark before scratching hyphae.…”

Contribution of the Mitochondrial Carbonic Anhydrase (MoCA1) to Conidiogenesis and Pathogenesis in Magnaporthe oryzae

“…As some proteins are constitutively synthesized by house-keeping genes at all developmental stages for the maintenance of primary cellular function there are some other group of proteins that are selectively expressed in response to the prevailing physiological and cellular need of the organism ( Zhang and Li, 2004 ), for this, we observed the expression pattern of MoCA1 at different developmental stages of M. oryzae and found that MoCA1 expression was specifically higher at the conidiophore stalk development and infectious stage ( Figures 2B , C ) which shows that MoCA1 is selectively expressed during M. oryzae life cycle especially during conidiation and pathogenic phase. Conidiation plays a key role not only in the survival and propagation of fungi under harsh environmental conditions but also facilitates the efficient disease prolongation ( Wyatt et al, 2013 ; Batool et al, 2021 ). Here we showed that the disruption of MoCA1 resulted in the impaired conidiophore formation, decreased conidiation and changes in appressorial development and melanization ( Figure 3 ).…”

A cold-water fish striving in a warming ocean: Insights from whole-genome sequencing of the Greenland halibut in the Northwest Atlantic

“…Moreover, other putative candidate genes involved in the differentiation between the Gulf and the Atlantic support this scenario of ongoing adaption to environmental change. In Chr07, the transcript of the translation initiation factor eIF4E, known to regulate stress homeostasis and modulate host invasion (Batool et al, 2021), seems under selection. The detected Zinc finger protein 365 in Chr12 has been recently defined as a new maternal LPS-binding protein that defends zebrafish embryos against gram-negative bacterial infections (Du et al, 2018) and, in Chr15, the detected guanylate cyclase activator 1d has been shown to be involved into the regulation of the photoreceptor GC in the teleost's retina (Imanishi et al, 2004).…”