Fig 1.
The hyphal growth and differentiation of A. oryzae under different temperatures for 72 h.
(A-E) The phenotypes of A. oryzae on PDA media were incubated at different temperature, including 22, 25, 30, 35, and 42°C for 72 h from left to right. (F) The colony sizes based on the diameter of the colonies. (G and H) The number of spores and dry biomass of A. oryzae mycelia under different temperature treatments. All values are mean ± SD of three replicates per treatment. The different lower-case letters indicate significant differences (P<0.05, n = 3), while the same letters indicate insignificant differences.
Table 1.
Summary of the sequencing data and gene numbers of A. oryzae transcriptome under three temperature treatments.
Fig 2.
Different types of alternative splicing (AS) events among the comparison groups subjected to different temperatures.
The horizontal axis indicates the type of alternative splicing, while the vertical axis indicates the number of differential alternative splicing events. AS, alternative splicing. JC, junction count. SE, skipped exon. RI, retained intron. MXE, mutually exclusive exon. A5SS, alternative 5’ splice site (junctions start inside an exon and end up with the initiation site of another exon). A3SS, alternative 3’ splice site (junctions start from an exon termination site and end up inside another exon). LT, samples incubated at 22°C. CK, samples incubated at 30°C. HT, samples incubated at 42°C.
Fig 3.
Analysis of the DEGs in A. oryzae incubated at different temperatures.
(A) The distribution of DEGs between each pair of compared transcriptomes. (B) Venn diagram of DEGs A. oryzae incubated at different temperatures. The Venn diagram was generated using Venny 2.1 software (https://bioinfogp.cnb.csic.es/tools/venny/index.html). (C) A heatmap of 265 co-expressed DEGs in three temperature treatments. Red and green represent the upregulated and downregulated genes, respectively. The heatmap was generated using HemI_windows_1_0 software (http://hemi.biocuckoo.org/down.php). LT, samples incubated at 22°C. CK, samples incubated at 30°C. HT, samples incubated at 42°C.
Fig 4.
GO and KEGG pathway enrichment analyses of the DEGs under different temperature stresses.
(A) The enriched GO terms of all the DEGs in response to temperature stress. (B, C) Top 10 enriched pathways in LT-vs-CK and HT-vs-CK, respectively. The black boxes represent the lipid metabolic pathways, while the red boxes represent the sugar metabolic pathways. GO, Gene Ontology. KEGG, Kyoto Encyclopedia of Genes and Genomes. DEGs, differentially expressed genes. LT, samples incubated at 22°C. CK, samples incubated at 30°C. HT, samples incubated at 42°C.
Fig 5.
KEGG enrichment analysis of DEGs encoding key enzymes involved in the sugar metabolic pathways.
Red and green indicate that the gene expressions were upregulated and downregulated, respectively. Grey indicates insignificant gene expressions. GLA, alpha-galactosidase. galM, aldose 1-epimerase. galK, galactokinase. galT, UDPglucose—hexose-1-phosphate uridylyltransferase. UGP2, UTP—glucose-1-phosphate uridylyltransferase. amyA, alpha-amylase. MGAM, maltase-glucoamylase. SI, sucrase-isomaltase. treT, trehalose synthase. otsA, trehalose 6-phosphate synthase. otsB, trehalose 6-phosphate phosphatase. TREH, alpha, alpha-trehalase. SOU1, sorbose reductase. SORD, L-iditol 2-dehydrogenase. HK, hexokinase. srlD, sorbitol-6-phosphate 2-dehydrogenase. srlB, glucitol/sorbitol PTS system EIIA component. MKI, mannose isomerase. ManA, mannose-6-phosphate isomerase. KEGG, Kyoto Encyclopedia of Genes and Genomes. DEGs, differentially expressed genes. LT, samples incubated at 22°C. CK, samples incubated at 30°C. HT, samples incubated at 42°C.
Fig 6.
Intracellular sugar concentrations in A. oryzae under different temperature stress.
The bars represent the average (± SE) of three replicates per treatment. LT, samples incubated at 22°C. CK, samples incubated at 30°C. HT, samples incubated at 42°C.
Fig 7.
Effects of exogenous sugar on the growth of A. oryzae under low and high-temperature stress.
(A) Phenotypes of A. oryzae cultured on CD medium supplemented with 4 and 8 g/100 mL of starch, fructose, and galactose or 96 h. (B-D) The colony sizes of A. oryzae cultured on CD media supplemented with starch, fructose, or galactose, respectively. (E-G) The spore density of A. oryzae cultured on CD media supplemented with starch, fructose, or galactose, respectively. CD medium with no sugar was used as the control. The values represent the average of three replicates ± SD, at a P<0.01 level of significance.
Fig 8.
The KEGG pathways for glycerolipid and glycerophospholipid metabolism and the relative contents of their metabolites.
(A) Key enzymes encoded by the DEGs in the glycerolipid and glycerophospholipid metabolism pathways. Red and green indicate the genes were upregulated and downregulated, respectively, while grey indicates no significant differences in the pathways. ALDH, aldehyde dehydrogenase. ADH, alcohol dehydrogenase. GK, glycerol kinase. GPAT, glycerol-3-phosphate O-acyltransferase. AGPAT, 1-acylglycerol-3-phosphate acyltransferase. PPAP, phosphatic acid phosphatase. DGAT, diacylglycerol O-acyltransferase 1. TAGL, triacylglycerol lipase. CPT1, diacylglycerol cholinephosphotransferase. EPT1, ethanolaminephosphotransferase. PLC, phospholipase C. PLD, phospholipase D. CDS1, phosphatidate cytidylyltransferase. CDIPT, CDP-diacylglycerol—inositol 3-phosphatidyltransferase. CHO1, CDP-diacylglycerol—serine O-phosphatidyltransferase. PISD, phosphatidylserine decarboxylase. SPLA2, secretory phospholipase A2. LPLI, lysophospholipase I. GDE1, glycerophosphodiester phosphodiesterase. Relative content of (B) triacylglycerol, (C) phosphatidylcholine, (D) phosphatidylethanolamine, (E) phosphatidylserine, and (F) phosphatidylinositol under low- or high-temperature stress. P<0.01 was considered the level of statistical significance. LT, samples incubated at 22°C. CK, samples incubated at 30°C. HT, samples incubated at 42°C.
Fig 9.
DEGs involved in the linoleic acid biosynthetic pathways, and the metabolite changes in response to temperature stress.
(A) The expression pattern of the DEGs involved in the linoleic acid biosynthetic pathways. The changes in (B) alpha-linolenic acid (C18:3), (C) lecithin, (D) linoleate (C18:2), and (E) 10(R)-HPODE (C18:2) in response to temperature stress. The bars represent the average (± SD.) of three biological replicates. P<0.01 and P<0.05 were considered levels of statistical significance. PLA2G, phospholipase A2. PPOC, linoleate 10R-lipoxygenase. DEGs, differentially expressed genes. LT, samples incubated at 22°C. CK, samples incubated at 30°C. HT, samples incubated at 42°C.