Experimental evidence for the functional importance and adaptive advantage of A-to-I RNA editing in fungi.

Adenosine-to-inosine (A-to-I) editing is the most prevalent type of RNA editing in animals, and it occurs in fungi specifically during sexual reproduction. However, it is debatable whether A-to-I RNA editing is adaptive. Deciphering the functional importance of individual editing sites is essential for the mechanistic understanding of the adaptive advantages of RNA editing. Here, by performing gene deletion for 17 genes with conserved missense editing (CME) sites and engineering underedited (ue) and overedited (oe) mutants for 10 CME sites using site-specific mutagenesis at the native locus in Fusarium graminearum, we demonstrated that two CME sites in CME5 and CME11 genes are functionally important for sexual reproduction. Although the overedited mutant was normal in sexual reproduction, the underedited mutant of CME5 had severe defects in ascus and ascospore formation like the deletion mutant, suggesting that the CME site of CME5 is co-opted for sexual development. The preediting residue of Cme5 is evolutionarily conserved across diverse classes of Ascomycota, while the postediting one is rarely hardwired into the genome, implying that editing at this site leads to higher fitness than a genomic A-to-G mutation. More importantly, mutants expressing only the underedited or the overedited allele of CME11 are defective in ascosporogenesis, while those expressing both alleles displayed normal phenotypes, indicating that concurrently expressing edited and unedited versions of Cme11 is more advantageous than either. Our study provides convincing experimental evidence for the long-suspected adaptive advantages of RNA editing in fungi and likely in animals.

A non-pheromone GPCR is essential for meiosis and ascosporogenesis in the wheat scab fungus.

Meiosis is essential for generating genetic diversity and sexual spores, but the regulation of meiosis and ascosporogenesis is not clear in filamentous fungi, in which dikaryotic and diploid cells formed inside fruiting bodies are not free living and independent of pheromones or pheromone receptors. In this study, Gia1, a non-pheromone GPCR (G protein-coupled receptor) with sexual-specific expression in Fusarium graminearum, is found to be essential for ascosporogenesis. The gia1 mutant was normal in perithecium development, crozier formation, and karyogamy but failed to undergo meiosis, which could be partially rescued by a dominant active mutation in GPA1 and activation of the Gpmk1 pathway. GIA1 orthologs have conserved functions in regulating meiosis and ascosporogenesis in Sordariomycetes. GIA1 has a paralog, GIP1, in F. graminearum and other Hypocreales species which is essential for perithecium formation. GIP1 differed from GIA1 in expression profiles and downstream signaling during sexual reproduction. Whereas the C-terminal tail and IR3 were important for intracellular signaling, the N-terminal region and EL3 of Gia1 were responsible for recognizing its ligand, which is likely a protein enriched in developing perithecia, particularly in the gia1 mutant. Taken together, these results showed that GIA1 encodes a non-pheromone GPCR that regulates the entry into meiosis and ascosporogenesis via the downstream Gpmk1 MAP kinase pathway in F. graminearum and other filamentous ascomycetes.

Discovery and Characterization of Putative Glycoprotein-Encoding Mycoviruses in the Bunyavirales.

Although segmented negative-sense RNA viruses (SNSRVs) have been frequently discovered in various fungi, most SNSRVs reported only the large segments. In this study, we investigated the diversity of the mycoviruses in the phytopathogenic fungus Fusarium asiaticum using the metatranscriptomic technique. We identified 17 fungal single-stranded RNA (ssRNA) viruses including nine viruses within Mitoviridae, one each in Narnaviridae, Botourmiaviridae, Hypoviridae, Fusariviridae, and Narliviridae, two in Mymonaviridae, and one trisegmented virus temporarily named Fusarium asiaticum mycobunyavirus 1 (FaMBV1). The FaMBV1 genome comprises three RNA segments, large (L), medium (M), and small (S) with 6,468, 2,639, and 1,420 nucleotides, respectively. These L, M, and S segments putatively encode the L protein, glycoprotein, and nucleocapsid, respectively. Phylogenetic analysis based on the L protein showed that FaMBV1 is phylogenetically clustered with Alternaria tenuissima negative-stranded RNA virus 2 (AtNSRV2) and Sclerotinia sclerotiorum negative-stranded RNA virus 5 (SsNSRV5) but distantly related to the members of the family Phenuiviridae. FaMBV1 could be vertically transmitted by asexual spores with lower efficiency (16.7%, 2/42). Comparison between FaMBV1-free and -infected fungal strains revealed that FaMBV1 has little effect on hyphal growth, pathogenicity, and conidium production, and its M segment is dispensable for viral replication and lost during subculture and asexual conidiation. The M and S segments of AtNSRV2 and SsNSRV5 were found using bioinformatics methods, indicating that the two fungal NSRVs harbor trisegmented genomes. Our results provide a new example of the existence and evolution of the segmented negative-sense RNA viruses in fungi. IMPORTANCE Fungal segmented negative-sense RNA viruses (SNSRVs) have been frequently found. Only the large segment encoding RNA-dependent RNA polymerase (RdRp) has been reported in most fungal SNSRVs, except for a few fungal SNSRVs reported to encode nucleocapsids, nonstructural proteins, or movement proteins. Virome analysis of the Fusarium spp. that cause Fusarium head blight discovered a novel virus, Fusarium asiaticum mycobunyavirus 1 (FaMBV1), representing a novel lineage of the family Phenuiviridae. FaMBV1 harbors a trisegmented genome that putatively encodes RdRp, glycoproteins, and nucleocapsids. The putative glycoprotein was first described in fungal SNSRVs and shared homology with glycoprotein of animal phenuivirus but was dispensable for its replication in F. asiaticum. Two other trisegmented fungal SNSRVs that also encode glycoproteins were discovered, implying that three-segment bunyavirus infections may be common in fungi. These findings provide new insights into the ecology and evolution of SNSRVs, particularly those infecting fungi.

Recognition of glycoside hydrolase 12 proteins by the immune receptor RXEG1 confers Fusarium head blight resistance in wheat.

Fusarium head blight (FHB), caused by Fusarium graminearum, is a devastating disease in wheat (Triticum aestivum) that results in substantial yield losses and mycotoxin contamination. Reliable genetic resources for FHB resistance in wheat are lacking. In this study, we characterized glycoside hydrolase 12 (GH12) family proteins secreted by F. graminearum. We established that two GH12 proteins, Fg05851 and Fg11037, have functionally redundant roles in F. graminearum colonization of wheat. Furthermore, we determined that the GH12 proteins Fg05851 and Fg11037 are recognized by the leucine-rich-repeat receptor-like protein RXEG1 in the dicot Nicotiana benthamiana. Heterologous expression of RXEG1 conferred wheat responsiveness to Fg05851 and Fg11037, enhanced wheat resistance to F. graminearum and reduced levels of the mycotoxin deoxynivalenol in wheat grains in an Fg05851/Fg11037-dependent manner. In the RXEG1 transgenic lines, genes related to pattern-triggered plant immunity, salicylic acid, jasmonic acid, and anti-oxidative homeostasis signalling pathways were upregulated during F. graminearum infection. However, the expression of these genes was not significantly changed during infection by the deletion mutant ΔFg05851/Fg11037, suggesting that the recognition of Fg05851/Fg11037 by RXEG1 triggered plant resistance against FHB. Moreover, introducing RXEG1 into three other different wheat cultivars via crossing also conferred resistance to F. graminearum. Expression of RXEG1 did not have obvious deleterious effects on plant growth and development in wheat. Our study reveals that N. benthamiana RXEG1 remains effective when transferred into wheat, a monocot, which in turn suggests that engineering wheat with interfamily plant immune receptor transgenes is a viable strategy for increasing resistance to FHB.

Fusarium BP1 is a reader of H3K27 methylation.

Histone H3 lysine 27 methylation catalyzed by polycomb repressive complex 2 (PRC2) is conserved from fungi to humans and represses gene transcription. However, the mechanism for recognition of methylated H3K27 remains unclear, especially in fungi. Here, we found that the bromo-adjacent homology (BAH)-plant homeodomain (PHD) domain containing protein BAH-PHD protein 1 (BP1) is a reader of H3K27 methylation in the cereal fungal pathogen Fusarium graminearum. BP1 interacts with the core PRC2 component Suz12 and directly binds methylated H3K27. BP1 is distributed in a subset of genomic regions marked by H3K27me3 and co-represses gene transcription. The BP1 deletion mutant shows identical phenotypes on mycelial growth and virulence, as well as similar expression profiles of secondary metabolite genes to the strain lacking the H3K27 methyltransferase Kmt6. More importantly, BP1 can directly bind DNA through its PHD finger, which might increase nucleosome residence and subsequently reinforce transcriptional repression in H3K27me3-marked target regions. A phylogenetic analysis showed that BP1 orthologs are mainly conserved in fungi. Overall, our findings provide novel insights into the mechanism by which PRC2 mediates gene repression in fungi, which is distinct from the PRC1-PRC2 system in plants and mammals.

Opposing functions of Fng1 and the Rpd3 HDAC complex in H4 acetylation in Fusarium graminearum.

Histone acetylation, balanced by histone acetyltransferase (HAT) and histone deacetylase (HDAC) complexes, affects dynamic transitions of chromatin structure to regulate transcriptional accessibility. However, little is known about the interplay between HAT and HDAC complexes in Fusarium graminearum, a causal agent of Fusarium Head Blight (FHB) that uniquely contains chromosomal regions enriched for house-keeping or infection-related genes. In this study, we identified the ortholog of the human inhibitor of growth (ING1) gene in F. graminearum (FNG1) and found that it specifically interacts with the FgEsa1 HAT of the NuA4 complex. Deletion of FNG1 led to severe growth defects and blocked conidiation, sexual reproduction, DON production, and plant infection. The fng1 mutant was normal in H3 acetylation but significantly reduced in H4 acetylation. A total of 34 spontaneous suppressors of fng1 with faster growth rate were isolated. Most of them were still defective in sexual reproduction and plant infection. Thirty two of them had mutations in orthologs of yeast RPD3, SIN3, and SDS3, three key components of the yeast Rpd3L HDAC complex. Four mutations in these three genes were verified to suppress the defects of fng1 mutant in growth and H4 acetylation. The rest two suppressor strains had a frameshift or nonsense mutation in a glutamine-rich hypothetical protein that may be a novel component of the FgRpd3 HDAC complex in filamentous fungi. FgRpd3, like Fng1, localized in euchromatin. Deletion of FgRPD3 resulted in severe growth defects and elevated H4 acetylation. In contract, the Fgsds3 deletion mutant had only a minor reduction in growth rate but FgSIN3 appeared to be an essential gene. RNA-seq analysis revealed that 48.1% and 54.2% of the genes with altered expression levels in the fng1 mutant were recovered to normal expression levels in two suppressor strains with mutations in FgRPD3 and FgSDS3, respectively. Taken together, our data showed that Fng1 is important for H4 acetylation as a component of the NuA4 complex and functionally related to the FgRpd3 HDAC complex for transcriptional regulation of genes important for growth, conidiation, sexual reproduction, and plant infection in F. graminearum.

High-Quality Genome Resource of Fusarium pseudograminearum Isolate Fp22-2 by Oxford Nanopore Long-Read Sequencing.

Fusarium crown rot (FCR), caused by Fusarium pseudograminearum, results in severe yield and quality losses of cereal crops in many arid and semiarid areas of the world. Limited information about the genome of F. pseudograminearum restricts the pathogenesis research and breeding of disease-resistant wheat varieties. In this study, a high-quality genome assembly of F. pseudograminearum isolate Fp22-2 was generated using Oxford Nanopore long-read sequencing technology. The assembled nuclear genome of Fp22-2 is 37.33 Mb with a repeat content of 3.69% and is divided into four contigs with a k-mer completeness score of 97.2% and a base quality accuracy of >99.99%. A total of 14,475 protein-coding genes (BUSCO completeness score, 99.9%) were predicted and functionally annotated. Moreover, genes encoding pathogenic proteins, including effector proteins and carbohydrate-active enzymes, and secondary metabolic gene clusters were identified. Overall, the high-quality genome assembly and gene annotation provided here will allow further investigation of the biology of F. pseudograminearum and lead to the development of new control options for FCR.

The Fng3 ING protein regulates H3 acetylation and H4 deacetylation by interacting with two distinct histone-modifying complexes.

The steady-state level of histone acetylation is maintained by histone acetyltransferase (HAT) and histone deacetylase (HDAC) complexes. INhibitor of Growth (ING) proteins are key components of the HAT or HDAC complexes but their relationship with other components and roles in phytopathogenic fungi are not well-characterized. Here, the FNG3 ING gene was functionally characterized in the wheat head blight fungus Fusarium graminearum. Deletion of FNG3 results in defects in fungal development and pathogenesis. Unlike other ING proteins that are specifically associated with distinct complexes, Fng3 was associated with both NuA3 HAT and FgRpd3 HDAC complexes to regulate H3 acetylation and H4 deacetylation. Whereas FgNto1 mediates the FgSas3-Fng3 interaction in the NuA3 complex, Fng3 interacted with the C-terminal region of FgRpd3 that is present in Rpd3 orthologs from filamentous fungi but absent in yeast Rpd3. The intrinsically disordered regions in the C-terminal tail of FgRpd3 underwent phase separation, which was important for its interaction with Fng3. Furthermore, the ING domain of Fng3 is responsible for its specificities in protein-protein interactions and functions. Taken together, Fng3 is involved in the dynamic regulation of histone acetylation by interacting with two histone modification complexes, and is important for fungal development and pathogenicity.

Landscape and regulation of alternative splicing and alternative polyadenylation in a plant pathogenic fungus.

Alternative splicing (AS) and alternative polyadenylation (APA) contribute significantly to the regulation of gene expression in higher eukaryotes. Their biological impact in filamentous fungi, however, is largely unknown. Here we combine PacBio Isoform-Sequencing and strand-specific RNA-sequencing of multiple tissues and mutant characterization to reveal the landscape and regulation of AS and APA in Fusarium graminearum. We generated a transcript annotation comprising 51 617 isoforms from 17 189 genes. In total, 4997 and 11 133 genes are alternatively spliced and polyadenylated, respectively. Majority of the AS events alter coding sequences. Unexpectedly, the AS transcripts containing premature-termination codons are not sensitive to nonsense-mediated messenger RNA decay. Unlike in yeasts and animals, distal APA sites have strong signals, but proximal APA isoforms are highly expressed in F. graminearum. The 3'-end processing factors FgRNA15, FgHRP1, and FgFIP1 play roles in promoting proximal APA site usage and intron splicing. A genome-wide increase in intron inclusion and distal APA site usage and downregulation of the spliceosomal and 3'-end processing factors were observed in older and quiescent tissues, indicating intron inclusion and 3'-untranslated region lengthening as novel mechanisms in regulating aging and dormancy in fungi. This study provides new insights into the complexity and regulation of AS and APA in filamentous fungi.

FgCsn12 Is Involved in the Regulation of Ascosporogenesis in the Wheat Scab Fungus Fusarium graminearum.

Fusarium head blight (FHB), caused by the fungal pathogen Fusarium graminearum, is a destructive disease worldwide. Ascospores are the primary inoculum of F. graminearum, and sexual reproduction is a critical step in its infection cycle. In this study, we characterized the functions of FgCsn12. Although the ortholog of FgCsn12 in budding yeast was reported to have a direct interaction with Csn5, which served as the core subunit of the COP9 signalosome, the interaction between FgCsn12 and FgCsn5 was not detected through the yeast two-hybrid assay. The deletion of FgCSN12 resulted in slight defects in the growth rate, conidial morphology, and pathogenicity. Instead of forming four-celled, uninucleate ascospores, the Fgcsn12 deletion mutant produced oval ascospores with only one or two cells and was significantly defective in ascospore discharge. The 3'UTR of FgCsn12 was dispensable for vegetative growth but essential for sexual reproductive functions. Compared with those of the wild type, 1204 genes and 2240 genes were up- and downregulated over twofold, respectively, in the Fgcsn12 mutant. Taken together, FgCsn12 demonstrated an important function in the regulation of ascosporogenesis in F. graminearum.

FgBUD14 is important for ascosporogenesis and involves both stage-specific alternative splicing and RNA editing during sexual reproduction.

In wheat head blight fungus Fusarium graminearum, A-to-I RNA editing occurs specifically during sexual reproduction. Among the genes with premature stop codons (PSCs) that require RNA editing to encode full-length proteins, FgBUD14 also had alternative splicing events in perithecia. In this study, we characterized the functions of FgBUD14 and its post-transcriptional modifications during sexual reproduction. The Fgbud14 deletion mutant was slightly reduced in growth, conidiation and virulence. Although deletion of FgBUD14 had no effect on perithecium morphology, the Fgbud14 mutant was defective in crozier formation and ascus development. The FgBud14-GFP localized to the apex of ascogenous hyphae and croziers, which may be related to its functions during early sexual development. During vegetative growth and asexual reproduction, FgBud14-GFP localized to hyphal tips and both ends of conidia. Furthermore, mutations blocking the splicing of intron 2 that has the PSC site had no effect on the function of FgBUD14 during sexual reproduction but caused a similar defect in growth with Fgbud14 mutant. Expression of the non-editable FgBUD14Intron2-TAA mutant allele also failed to complement the Fgbud14 mutant. Taken together, FgBUD14 plays important roles in ascus development, and both alternative splicing and RNA editing occur specifically to its transcripts during sexual reproduction in F. graminearum.

Comparative transcriptome analysis reveals distinct gene expression profiles in Brachypodium distachyon infected by two fungal pathogens.

BACKGROUND: The production of cereal crops is frequently affected by diseases caused by Fusarium graminearum and Magnaporthe oryzae, two devastating fungal pathogens. To improve crop resistance, many studies have focused on understanding the mechanisms of host defense against these two fungi individually. However, our knowledge of the common and different host defenses against these pathogens is very limited. RESULTS: In this study, we employed Brachypodium distachyon as a model for cereal crops and performed comparative transcriptomics to study the dynamics of host gene expression at different infection stages. We found that infection with either F. graminearum or M. oryzae triggered massive transcriptomic reprogramming in the diseased tissues. Numerous defense-related genes were induced with dynamic changes during the time course of infection, including genes that function in pattern detection, MAPK cascade, phytohormone signaling, transcription, protein degradation, and secondary metabolism. In particular, the expression of jasmonic acid signaling genes and proteasome component genes were likely specifically inhibited or manipulated upon infection by F. graminearum. CONCLUSIONS: Our analysis showed that, although the affected host pathways are similar, their expression programs and regulations are distinct during infection by F. graminearum and M. oryzae. The results provide valuable insight into the interactions between B. distachyon and two important cereal pathogens.

Stage-specific regulation of purine metabolism during infectious growth and sexual reproduction in Fusarium graminearum.

Ascospores generated during sexual reproduction are the primary inoculum for the wheat scab fungus Fusarium graminearum. Purine metabolism is known to play important roles in fungal pathogens but its lifecycle stage-specific regulation is unclear. By characterizing the genes involved in purine de novo and salvage biosynthesis pathways, we showed that de novo syntheses of inosine, adenosine and guanosine monophosphates (IMP, AMP and GMP) are important for vegetative growth, sexual/asexual reproduction, and infectious growth, whereas purine salvage synthesis is dispensable for these stages in F. graminearum. Addition of GMP rescued the defects of the Fgimd1 mutant in vegetative growth and conidiation but not sexual reproduction, whereas addition of AMP rescued all of these defects of the Fgade12 mutant, suggesting that the function of de novo synthesis of GMP rather than AMP is distinct in sexual stages. Moreover, Acd1, an ortholog of AMP deaminase, is dispensable for growth but essential for ascosporogenesis and pathogenesis, suggesting that AMP catabolism has stage-specific functions during sexual reproduction and infectious growth. The expression of almost all the genes involved in de novo purine synthesis is downregulated during sexual reproduction and infectious growth relative to vegetative growth. This study revealed that F. graminearum has stage-specific regulation of purine metabolism during infectious growth and sexual reproduction.

High-Quality Genome Resource of Clonostachys rosea Strain CanS41 by Oxford Nanopore Long-Read Sequencing.

Clonostachys rosea is a necrotrophic mycoparasitic fungus with excellent biological control ability against numerous fungal plant pathogens. Here, we performed genomic sequencing of C. rosea strain CanS41 using Oxford Nanopore sequencing technology. We generated a high-quality genome assembly (>99.99% accuracy), which comprised 26 contigs containing 60.68 Mb sequences with a GC content of 48.55% and a repeat content of 8.38%. The N50 contig length is 3.02 Mb. In total, 20,818 protein-coding genes were identified and functionally annotated. Genes encoding secreted proteins and carbohydrate-active enzymes as well as secondary metabolic gene clusters were also identified and analyzed. In summary, the high-quality genome assembly and gene annotation provided here will allow further exploration of biological functions and enhance biological control ability of C. rosea.

The meiosis-specific APC activator FgAMA1 is dispensable for meiosis but important for ascosporogenesis in Fusarium graminearum.

Ascospores are the primary inoculum in Fusarium graminearum. Interestingly, 70 of its genes have premature stop codons (PSC) and require A-to-I editing during sexual reproduction to encode full-length proteins, including the ortholog of yeast Ama1, a meiosis-specific activator of APC/C. In this study, we characterized the function of FgAMA1 and its PSC editing. FgAMA1 was specifically expressed during sexual reproduction. The Fgama1 mutant was normal in growth and perithecium formation but defective in ascospogenesis. Instead of forming four-celled, uninucleate ascospores, Fgama1 mutant produced oval, single-celled, binucleated ascospores by selfing. Some mutant ascospores began to bud and underwent additional mitosis inside asci. Expression of the wild-type or edited FgAMA1 but not the uneditable allele complemented Fgama1. In the Fgama1 x mat-1-1 outcross, over 60% of the asci had eight Fgama1 or intermediate (elongated but single-celled) ascospores, suggesting efficient meiotic silencing of unpaired FgAMA1. Deletion of FgPAL1, one of the genes upregulated in Fgama1 also resulted in defects in ascospore morphology and budding. Overall, our results showed that FgAMA1 is dispensable for meiosis but important for ascospore formation and discharge. In F. graminearum, whereas some of its targets are functional during meiosis, FgAma1 may target other proteins that function after spore delimitation.

The SR-protein FgSrp2 regulates vegetative growth, sexual reproduction and pre-mRNA processing by interacting with FgSrp1 in Fusarium graminearum.

Serine/arginine (SR) proteins play significant roles in pre-mRNA splicing in eukaryotes. To investigate how gene expression influences fungal development and pathogenicity in Fusarium graminearum, a causal agent of Fusarium head blight (FHB) of wheat and barley, our previous study identified a SR protein FgSrp1 in F. graminearum, and showed that it is important for conidiation, plant infection and pre-mRNA processing. In this study, we identified another SR protein FgSrp2 in F. graminearum, which is orthologous to Schizosaccharomyces pombe Srp2. Our data showed that, whereas yeast Srp2 is essential for growth, deletion of FgSRP2 resulted in only slight defects in vegetative growth and perithecia melanization. FgSrp2 localized to the nucleus and both its N- and C-terminal regions were important for the localization to the nucleus. FgSrp2 interacted with FgSrp1 to form a complex in vivo. Double deletion of FgSRP1 and FgSRP2 revealed that they had overlapping functions in vegetative growth and sexual reproduction. RNA-seq analysis revealed that, although deletion of FgSRP2 alone had minimal effects, deletion of both FgSRP1 and FgSRP2 caused significant changes in gene transcription and RNA splicing. Overall, our results indicated that FgSrp2 regulates vegetative growth, sexual reproduction and pre-mRNA processing by interacting with FgSrp1.

Cancer-related fatigue and biochemical parameters among cancer patients with different stages of sarcopenia.

PURPOSE: Cancer-related fatigue (CRF) is a pervasive symptom experienced by cancer patients. Sarcopenia has been suggested as a treatment target of CRF. This study aims to assess the differences of CRF and biochemical markers among different stages of sarcopenia which remain poorly delineated. METHODS: A total of 187 patients were included in this cross-sectional study. Based on muscle mass (skeletal muscle index, SMI), muscle strength (handgrip strength), and physical performance (SARC-F score), patients were divided into four groups (non-sarcopenia, pre-sarcopenia, sarcopenia, and severe sarcopenia). Cancer-related fatigue was measured by the Brief Fatigue Inventory (BFI). Biochemical markers were measured by routine blood tests. RESULTS: The BFI score was significantly associated with sarcopenia stage (r=0.500; P<0.001). Cancer patients in severe sarcopenia group suffered from worse CRF than those in non-sarcopenia, pre-sarcopenia, and sarcopenia groups (P<0.001). In the multivariate linear regression model (R2=0.542), CRF was significantly correlated with SARC-F score (standardized B=0.519; P<0.001) and high-sensitivity C-reactive protein (standardized B=0.389; P=0.004). Serum albumin and cholinesterase were statistically correlated with both sarcopenia stage and CRF. CONCLUSIONS: The significantly increased occurrence and severity of CRF in cancer patients with sarcopenia suggest that sarcopenia may be a crucial target to improve the management of CRF. Circulating albumin and cholinesterase have the potential to predicting sarcopenia as biomarkers.

A-to-I mRNA editing in fungi: occurrence, function, and evolution.

A-to-I RNA editing is an important post-transcriptional modification that converts adenosine (A) to inosine (I) in RNA molecules via hydrolytic deamination. Although editing of mRNAs catalyzed by adenosine deaminases acting on RNA (ADARs) is an evolutionarily conserved mechanism in metazoans, organisms outside the animal kingdom lacking ADAR orthologs were thought to lack A-to-I mRNA editing. However, recent discoveries of genome-wide A-to-I mRNA editing during the sexual stage of the wheat scab fungus Fusarium graminearum, model filamentous fungus Neurospora crassa, Sordaria macrospora, and an early diverging filamentous ascomycete Pyronema confluens indicated that A-to-I mRNA editing is likely an evolutionarily conserved feature in filamentous ascomycetes. More importantly, A-to-I mRNA editing has been demonstrated to play crucial roles in different sexual developmental processes and display distinct tissue- or development-specific regulation. Contrary to that in animals, the majority of fungal RNA editing events are non-synonymous editing, which were shown to be generally advantageous and favored by positive selection. Many non-synonymous editing sites are conserved among different fungi and have potential functional and evolutionary importance. Here, we review the recent findings about the occurrence, regulation, function, and evolution of A-to-I mRNA editing in fungi.

PKA activity is essential for relieving the suppression of hyphal growth and appressorium formation by MoSfl1 in Magnaporthe oryzae.

In the rice blast fungus Magnaporthe oryzae, the cAMP-PKA pathway regulates surface recognition, appressorium turgor generation, and invasive growth. However, deletion of CPKA failed to block appressorium formation and responses to exogenous cAMP. In this study, we generated and characterized the cpk2 and cpkA cpk2 mutants and spontaneous suppressors of cpkA cpk2 in M. oryzae. Our results demonstrate that CPKA and CPK2 have specific and overlapping functions, and PKA activity is essential for appressorium formation and plant infection. Unlike the single mutants, the cpkA cpk2 mutant was significantly reduced in growth and rarely produced conidia. It failed to form appressoria although the intracellular cAMP level and phosphorylation of Pmk1 MAP kinase were increased. The double mutant also was defective in plant penetration and Mps1 activation. Interestingly, it often produced fast-growing spontaneous suppressors that formed appressoria but were still non-pathogenic. Two suppressor strains of cpkA cpk2 had deletion and insertion mutations in the MoSFL1 transcription factor gene. Deletion of MoSFL1 or its C-terminal 93-aa (MoSFL1ΔCT) was confirmed to suppress the defects of cpkA cpk2 in hyphal growth but not appressorium formation or pathogenesis. We also isolated 30 spontaneous suppressors of the cpkA cpk2 mutant in Fusarium graminearum and identified mutations in 29 of them in FgSFL1. Affinity purification and co-IP assays showed that this C-terminal region of MoSfl1 was essential for its interaction with the conserved Cyc8-Tup1 transcriptional co-repressor, which was reduced by cAMP treatment. Furthermore, the S211D mutation at the conserved PKA-phosphorylation site in MoSFL1 partially suppressed the defects of cpkA cpk2. Overall, our results indicate that PKA activity is essential for appressorium formation and proper activation of Pmk1 or Mps1 in M. oryzae, and phosphorylation of MoSfl1 by PKA relieves its interaction with the Cyc8-Tup1 co-repressor and suppression of genes important for hyphal growth.