BackgroundC-type cytoplasmic male sterility (CMS-C) is one of the three major types of cytoplasmic male sterility (CMS) in maize. Rf4 is a dominant restorer gene for CMS-C and has great value in hybrid maize breeding, but little information concerning its functional mechanism is known.ResultsTo reveal the functional mechanism of Rf4, we developed a pair of maize near-isogenic lines (NILs) for the Rf4 locus, which included a NIL_rf4 male-sterile line and a NIL_Rf4 male fertility-restored line. Genetic analysis and molecular marker detection indicated that the male fertility of NIL_Rf4 was controlled by Rf4. Whole-genome sequencing demonstrated genomic differences between the two NILs was clustered in the Rf4 mapping region. Unmapped reads of NILs were further assembled to uncover Rf4 candidates. RNA-Seq was then performed for the developing anthers of the NILs to identify critical genes and pathways associated with fertility restoration. A total of 7125 differentially expressed genes (DEGs) were identified. These DEGs were significantly enriched in 242 Gene Ontology (GO) categories, wherein 100 DEGs were involved in pollen tube development, pollen tube growth, pollen development, and gametophyte development. Homology analysis revealed 198 male fertility-related DEGs, and pathway enrichment analysis revealed that 58 DEGs were enriched in cell energy metabolism processes involved in glycolysis, the pentose phosphate pathway, and pyruvate metabolism. By querying the Plant Reactome Pathway database, we found that 14 of the DEGs were involved in the mitochondrial tricarboxylic acid (TCA) cycle and that most of them belonged to the isocitrate dehydrogenase (IDH) and oxoglutarate dehydrogenase (OGDH) enzyme complexes. Transcriptome sequencing and real-time quantitative PCR (qPCR) showed that all the above TCA cycle-related genes were up-regulated in NIL_Rf4. The results of our subsequent enzyme-linked immunosorbent assay (ELISA) experiments pointed out that the contents of both the IDH and OGDH enzymes accumulated more in the spikelets of NIL_Rf4 than in those of NIL_rf4.ConclusionThe present research provides valuable genomic resources for deep insight into the molecular mechanism underlying CMS-C male fertility restoration. Importantly, our results indicated that genes involved in energy metabolism, especially some mitochondrial TCA cycle-related genes, were associated with maize CMS-C male fertility restoration.Electronic supplementary materialThe online version of this article (10.1186/s12870-018-1409-z) contains supplementary material, which is available to authorized users.

No abstract

Multiple studies have shown that a single bout of exercise can increase insulin sensitivity in rats fed chow or a high fat diet (HFD). However, few studies have investigated signaling mechanisms for the improved insulin sensitivity following exercise in rats fed a HFD. Our purpose was to assess the effect of a physiologic insulin dose on skeletal muscle glucose uptake (GU) and Akt phosphorylation (pAkt) after acute exercise in rats fed either chow or HFD. Rats were randomly separated into 2 diet groups and either maintained on rat chow (low fat diet, LFD: 14% kcal fat) or provided HFD (60% kcal fat). After 2 wk of the diet, half of the rats from each group remained sedentary (LFD‐Sed & HFD‐Sed) or performed acute exercise (LFD‐Ex & HFD‐Ex; 4 × 30 min swim). At 3h post‐exercise (3hPEX), epitrochlearis muscles were isolated and incubated ex vivo (−/+ 100μU/mL insulin) for GU and pAkt measurements. Muscles from HFD‐Sed vs. LFD‐Sed rats had reduced insulin‐induced GU (~36%) and pAkt (~25%). At 3hPEX insulin‐induced GU and pAkt were restored in muscles from HFD‐Ex rats to LFD‐Sed levels. However, muscles from LFD‐Ex rats at 3hPEX vs LFD‐Sed rats had greater insulin‐induced GU (~65%) without increased pAkt. These results indicate that although exercise can enhance insulin‐induced GU in rats fed either LFD or HFD, greater insulin‐induced pAkt appears to be a potential mechanism for this benefit at 3hPEX only in HFD fed rats.