Inhibition of mitochondrial respiration under hypoxia and increased antioxidant activity after reoxygenation of <i>Tribolium castaneum</i>

<div><p>Regulating the air in low-oxygen environments protects hermetically stored grains from storage pests damage. However, pests that can tolerate hypoxic stress pose a huge challenge in terms of grain storage. We used various biological approaches to determine the fundamental mechanisms of <i>Tribolium castaneum</i> to cope with hypoxia. Our results indicated that limiting the available oxygen to <i>T</i>. <i>castaneum</i> increased glycolysis and inhibited the Krebs cycle, and that accumulated pyruvic acid was preferentially converted to lactic acid via anaerobic metabolism. Mitochondrial aerobic respiration was markedly suppressed for beetles under hypoxia, which also might have led to mitochondrial autophagy. The enzymatic activity of citrate synthase decreased in insects under hypoxia but recovered within 12 h, which suggested that the beetles recovered from the hypoxia. Moreover, hypoxia-reperfusion resulted in severe oxidative damage to insects, and antioxidant levels increased to defend against the high level of reactive oxygen species. In conclusion, our findings show that mitochondria were the main target in <i>T</i>. <i>castaneum</i> in response to low oxygen. The beetles under hypoxia inhibited mitochondrial respiration and increased antioxidant activity after reoxygenation. Our research advances the field of pest control and makes it possible to develop more efficient strategies for hermetic storage.</p></div

GO enrichment analysis of genes involves in the hypoxia resistance.

<p>The GO terms are sorted by —Log 10 of the enrichment <i>P</i>-value, which represent the enrichment significance of GO terms. The enrichment of GO terms are shown by comparing DEG with the whole genome.</p

Some hypoxia-response DEGs in the RNA-seq.

<p>Some hypoxia-response DEGs in the RNA-seq.</p

Variation in citrate synthase activity of <i>T</i>. <i>castaneum</i> under normoxia and hypoxia-reperfusion.

<p>The citrate synthase activity of different groups was analyzed by one-way ANOVA. Results are shown as mean ± SE. Tukey’s multiple test was used for pairwise comparison of the difference between treatment for mean separation (<i>P</i> < 0.05).</p

qRT-PCR analysis of selected transcripts to confirm expression profiles identified by RNA-seq.

<p><i>Tc</i>ELOVL, elongation of very long chain fatty acids protein 7; <i>Tc</i>MRP, ATP-binding cassette subfamily C (CFTR/MRP) member 4; <i>Tc</i>HSP70, heat shock 70kDa protein; <i>Tc</i>MAPK, MAP kinase; <i>Tc</i>DUSP, Dual specificity MAP kinase phosphatase; <i>Tc</i>SD, superoxide dismutase, Cu-Zn family; <i>Tc</i>AG, alpha-glucosidase; <i>Tc</i>DACHS, DACHS, Hippo signling pathway; <i>Tc</i>FJBP Four-jointed box protein 1 (FJBP). Value represents mean ± SE of three independent PCR amplifications and quantifications.</p

The activity of (A) SOD, (B) CAT, (C) GST and (D) MDA concentration of <i>T</i>. <i>castaneum</i> under normoxia and hypoxia-reperfusion.

<p>The bars represent means ± SE of three replicates. One-way ANOVA followed by Tukey’s range test was used for pairwise comparison of the difference between groups for mean separation (<i>P</i> < 0.05).</p

DataSheet_1_Physiological and transcriptome profiling revealed defense networks during Cladosporium fulvum and tomato interaction at the early stage.docx

Tomato leaf mold caused by Cladosporium fulvum (C. fulvum) is a serious fungal disease which results in huge yield losses in tomato cultivation worldwide. In our study, we discovered that ROS (reactive oxygen species) burst was triggered by C. fulvum treatment in tomato leaves. RNA-sequencing was used to identify differentially expressed genes (DEGs) induced by C. fulvum inoculation at the early stage of invasion in susceptible tomato plants. Gene ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases were used to annotate functions of DEGs in tomato plants. Based on our comparative analysis, DEGs related to plant-pathogen interaction pathway, plant hormone signal transduction pathway and the plant phenylpropanoid pathway were further analyzed. Our results discovered that a number of core defense genes against fungal invasion were induced and plant hormone signal transduction pathways were impacted by C. fulvum inoculation. Further, our results showed that SA (salicylic acid) and ABA (abscisic acid) contents were accumulated while JA (jasmonic acid) content decreased after C. fulvum inoculation in comparison with control, and quantitative real-time PCR to detect the relative expression of genes involved in SA, ABA and JA signaling pathway further confirmed our results. Together, results will contribute to understanding the mechanisms of C. fulvum and tomato interaction in future.</p