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In recent years, there has been an apparent Europe-wide emerging presence of brown spot needle blight, a disease of pine species caused by the fungus Lecanosticta acicola. In this study, we report ...

Rhynchosporium commune, the cause of barley scald, is an important disease of barley in Canada. Multiple studies have indicated that cryptic sexual reproduction may occur between opposite mating ty...

Neonectria ditissimaandN. faginataare canker pathogens involved in an insect-fungus disease complex of American beech (Fagus grandifolia) commonly known as beech bark disease (BBD). In Europe, bothN. ditissimaandN. coccineaare involved in BBD on European beech (Fagus sylvatica). Field observations across the range of BBD indicate that new infections occur primarily via ascospores. Both heterothallic (self-sterile) and homothallic (self-fertile) mating strategies have been reported forNeonectriafungi. As such, investigations into mating strategy are important for understanding both the disease cycle and population genetics ofNeonectria. This is particularly important in the U.S. given that over timeN. faginatadominates the BBD pathosystem despite high densities of non-beech hosts forN. ditissima. This study utilized whole-genome sequences of BBD-associatedNeonectriaspp. along with other publicly availableNeonectriaandCorinectriagenomes andin vitromating assays to characterize mating type (MAT) loci and confirm thallism for select members ofNeonectriaandCorinectria. MAT gene-specific primer pairs were developed to efficiently characterize the mating types of additional single ascospore strains ofN. ditissima,N. faginata, andN. coccineaand several other related species lacking genomic data.In vitromating assays were used in combination with molecular results to confirm thallism. These assays also comfirmed the sexual compatibility amongN. ditissimastrains from different plant hosts. Maximum likelihood phylogenetic analysis of both MAT1-1-1 and MAT1-2-1 sequences recovered trees with similar topology to previously published phylogenies ofNeonectriaandCorinectria. The results of this study indicate that allNeonectriaandCorinectriatested are heterothallic based on our limited sampling and, as such, thallism cannot help explain the inevitable dominance ofN. faginatain the BBD pathosystem.

Parkinson’s disease (PD) is one of the most prevailing aging diseases around the world. The present study was to investigate the potential effect of hydrogen sulfide (H(2)S) and silent mating type information regulation 2 homolog 1 (SIRT1) in MPP~+ induced SH-SY5Y cells and its underlying mechanisms in PD. SH-SY5Y cells were induced by MPP~+ and treated with the H(2)S donor NaHS to detect the effect of H(2)S on the molecular behaviors of MPP~+ induced SH-SY5Y cells. NaHS reduced the apoptosis rate and expressions of MDA, 4-HNE and p62, while increased cell viability, autophagy flux and expressions of LC3 II/I and Beclin1 in MPP~+ induced SH-SY5Y cells. Then, levels of autophagy-related proteins and inflammation-related proteins (TNF-α, IL-Iβ) were detected, indicating that Chloroquine and Sirtinol reversed the protective effect of H(2)S on SH-SY5Y cells induced by MPP~+. We further explored the particular function of H(2)S, SH-SY5Y cells treated with MPP~+, NaHS chloroquine, and SIRT1 inhibitor (Sirtinol). The results showed that H(2)S increased SIRT1 expression and sulfhydration. Finally, a PD mouse model verified the above results. In a word, H(2)S ameliorated SIRT1 activity through acceleration of SIRT1 sulfhydration to increase the autophagy flux and attenuate damage of SH-SY5Y cells induced by MPP~+. H(2)S and SIRT1 activator might be a target in the treatment of PD patients.

Pecan scab, caused by Venturia effusa, is the most prevalent disease of pecan in the southeastern United States. Recent characterization of the mating type (MAT) distribution of V. effusa revealed that the MAT idiomorphs are in equilibrium at various spatial scales, indicative of regular sexual recombination. However, the occurrence of the sexual stage of V. effusa has never been observed, and the pathogen was previously considered to rely entirely on asexual reproduction. We were able to generate the sexual stage by pairing isolates of opposite mating types on oatmeal culture media. Cultures were incubated at 24 C for 2 mo to allow hyphae from isolates of each mating type to interact. Culture plates were then incubated at 4 C for 4 mo, after which immature pseudothecia were observed. Following exposure to a 12-h photoperiod for 2 wk at 24 C, asci and ascospores readily developed. Pseudothecium and ascospore production was optimal when incubated for 4 mo at 4 C. We utilized progeny from a cross of an albino isolate and wild-type (melanized) isolates to determine that recombination had occurred. Multilocus genotyping using 32 microsatellite markers confirmed that progeny were the result of recombination, which was further supported by segregation of mating types and culture pigmentation. Albino progeny were all confirmed to contain the same mutation in the polyketide synthase (PKS1) melanin biosynthesis gene as the albino parent. The results of this study demonstrate the heterothallic nature of V. effusa. The impact of determining the source of the overwintering ascostroma will aid in management decisions to reduce the primary inoculum in the disease cycle.

True morels (Morchella spp.) are a group of edible fungi that are in high demand worldwide. However, this group of fungi remains poorly understood in terms of its genetic structure, life cycle, and mating system. In the present study, we cloned the MAT locus in Morchella sp. Mes-20 using long-range polymerase chain reaction (PCR) amplification. Our results showed that the MAT1-2 idiomorph in the single-ascospore isolate YAASMCB-3 was 7.5 kb in length, harboring a single MAT1-2-1 gene, whereas the MAT1-1 idiomorph in the isolate YAASMCB-15 was 7.8 kb, carrying both MAT1-1-1 and MAT1-1-10 genes. Mating-type diagnostic assays of single-ascospore populations confirmed that Mes-20 is heterothallic. In addition, 42 collections belonging to 17 morel species (7 black morel species [Elata clade], 9 yellow morel species [Esculenta clade], and 1 species from the Rufobrunnea clade) were used to clone and characterize the MAT1-1-1 and MAT1-2-1 genes for development of the mating gene genealogies. In concordance with the multilocus phylogenetic trees, collections for the respective species were readily distinguished by well-supported lineages in mating gene genealogies. The topologies were consistent within the Elata clade, whereas the branching order and sister-group relationships slightly varied within the Esculenta clade. Our results show that species in the genus Morchella could be delimited by mating gene genealogies.

International audience; Agaricus sinodeliciosus is an edible wild mushroom known in northwest China. It belongs to Agaricus section Bivelares that includes several popular cultivated species, such as A. bisporus, the button mushroom. The life cycle of the latter species has been described as amphithallic because both homokaryotic (n) and heterokaryotic (n+n) spores are produced that lead to heterothallic and pseudohomothallic life cycles, respectively. The type of life cycle can impact population structures and breeding strategies. The main objective of this study was to identify the different categories of spores produced by A. sinodeliciosus. Using either a morphological approach based on the number of sterigmata per basidium or a genetic approach based on the genotypes of the progeny at two loci, the proportion of heterokaryotic spores was estimated at 6% and 15%, respectively. Two codominant markers were chosen from the mitochondrial intermediate peptidase gene (MIP) and the nuc rDNA internal transcribed spacer (ITS1-5.8S-ITS2 = ITS) region. Genotypic analysis and mating tests confirmed that in A. sinodeliciosus, MIP is centromere-linked and tightly linked to the mating type locus as in A. bisporus and A. subrufescens. We conclude that A. sinodeliciosus has a unifactorial system of sexual incompatibility and an amphithallic life cycle that is predominantly heterothallic, and that its pseudohomothallism follows a nonrandom model with nonsister postmeiotic nuclei paired in the same spore, which give rise to a potentially fertile heterokaryon. This method of using two informative markers is reliable not only in selecting the homokaryotic offspring but also in classifying the homokaryons in two breeding stocks according to their mating type alleles.

Ciliates represent a morphologically and genetically distinct group of single-celled eukaryotes that segregate germline and somatic functions into two types of nuclei and exhibit complex cytogenetic events during the sexual process of conjugation, which is under the control of the so-called “mating type systems”. Studying conjugation in ciliates may provide insight into our understanding of the origins and evolution of sex and fertilization. In the present work, we studied in detail the sexual process of conjugation using the model species Euplotes vannus, and compared these nuclear events with those occurring in other ciliates. Our results indicate that in E. vannus: 1) conjugation requires about 75 hours to complete: the longest step is the development of the new macronucleus (ca. 64h), followed by the nuclear division of meiosis I (5h); the mitotic divisions usually take only 2h; 2) there are three prezygotic divisions (mitosis and meiosis I and II), and two of the eight resulting nuclei become pronuclei; 3) after the exchange and fusion of the pronuclei, two postzygotic divisions occur; two of the four products differentiate into the new micronucleus and macronucleus, respectively, and the parental macronucleus degenerates completely; 4) comparison of the nuclear events during conjugation in different ciliates reveals that there are generally three prezygotic divisions while the number of postzygotic divisions is highly variable. These results can serve as reference to investigate the mating type system operating in this species and to analyze genes involved in the different steps of the sexual process.

Oxidative stress is one of the key mechanisms of sepsis related organ dysfunction including stress hyperglycemia. Silent mating type information regulation 2 homolog 1 (SIRT1) could regulate glucose metabolism through its deacetylase activity. In this study, we aimed to investigate the role of SIRT1/forkhead box protein 1 (FoxO1) pathway on lipopolysaccharide (LPS) induced INS-1 cells dysfunction from aspects of oxidative stress and apoptosis. After being treated with 1 mg/L LPS together with or without SIRT1 activator resveratrol (RSV) or SIRT1 inhibitor EX527, cell viability, ROS generation, malondialdehyde (MDA), superoxide, insulin secretion, and activity of superoxide dismutase (SOD) in INS-1 cells were measured by specific assays. Protein expression of SIRT1, FoxO1, toll-like receptor 4 (TLR4), and acetylated FoxO1 (ac-FoxO1) were detected by western blot analysis. Nuclear and cytoplasmic protein was extracted respectively to analyze SIRT1 and FoxO1 redistribution. Mitochondrial potentials and apoptosis were detected by flow cytometry or observed under fluorescence microscope. Results showed that LPS decreased cell viability and insulin secretion, increased ROS, MDA, and superoxide generation, whereas inhibited SOD activity and FoxO1 nuclear transportation. Activation of SIRT1 by RSV down-regulated TLR4 expression, SIRT1 and FoxO1 nuclear protein expression increased after RSV pretreatment. Additionally, LPS induced decreased mitochondrial membrane potentials and structural abnormalities, which could be partially reversed by RSV. SIRT1/FoxO1 may be one of potential targets which could resist against LPS-induced INS-1 cells from oxidative stress damage and mitochondrial dysfunction.

A rapid and sensitive polymerase chain reaction (PCR) method was established for detection of mating types of Cochliobolus heterostrophus, the causal agent of southern corn leaf blight (SCLB). Two ...

Dothistroma needle blight (DNB) has been observed in Slovakia during the last two decades. Up until 2017, Dothistroma septosporum has only been detected and molecularly confirmed to cause DNB in Sl...

The aim of this study was to investigate the pattern of distribution of mating type (MAT) genes of Tuber indicum in ectomycorhizosphere soils from natural T. indicum-producing areas and cultivated truffle orchards and ascocarp samples from different regions. Quantitative real-time PCR and multiplex PCR were used to weight the copy numbers of MAT1-1-1 and MAT1-2-1 in natural truffle soils and cultivated orchard soils. The effect of limestone on the pattern of truffle MAT genes and the correlation between soil properties and the proportion of MAT genes were also assessed. These results indicated that an uneven and nonrandom distribution of MAT genes was common in truffle-producing areas, cultivated truffle orchards, and ascocarps gleba. The competition between the two mating type genes and the expansion of unbalanced distribution was found to be closely related to truffle fructification. Limestone treatments failed to alter the proportion of the two mating type genes in the soil. The content of available phosphorus in soil was significantly correlated with the value of MAT1-1-1/MAT1-2-1 in cultivated and natural ectomycorhizosphere soils. The application of real-time quantitative PCR can provide reference for monitoring the dynamic changes of mating type genes in soil. This study investigates the distributional pattern of T. indicum MAT genes in the ectomycorhizosphere soil and ascocarp gleba from different regions, which may provide a foundation for the cultivation of T. indicum.

The endophyte presence and diversity in natural populations of Poa alsodes were evaluated along a latitudinal transect from the southern distribution range in North Carolina to New York. Two distinct Epichloë hybrid taxa were identified from 23 populations. Each taxon could easily be distinguished by polymerase chain reaction (PCR) genotyping with primers designed to mating type genes and alkaloid biosynthesis genes that encode key pathway steps for ergot alkaloids, indole-diterpenes, lolines, and peramine. The most commonly found Epichloë taxon, Poa alsodes Taxonomic Group-1 (PalTG-1), was detected in 22 populations at high infection frequencies (72-100%), with the exception of one population at high elevation (26% infection). The second taxon, PalTG-2, was observed only in five populations in Pennsylvania constituting 12% of infected samples. Phylogenetic analyses placed PalTG-1 as an interspecific hybrid of E. amarillans and E. typhina subsp. poae ancestors, and it is considered a new hybrid species, which the authors name Epichloë alsodes. PalTG-2 is an intraspecific hybrid of two E. typhina subsp. poae ancestors, similar to E. schardlii from the host Cinna arundinacea, which the authors propose as a new variety, Epichloë schardlii var. pennsylvanica. Epichloë alsodes isolates were all mating type MTA MTB and tested positive for dmaW, easC, perA, and some LOL genes, but only the alkaloid N-acetylnorloline was detected in E. alsodes-infected plant material. Epichloë schardlii var. pennsylvanica isolates were all mating type MTB MTB and tested positive for perA, but peramine was not produced. Both E. alsodes and E. schardlii var. pennsylvanica appeared to have complete perA genes, but point mutations were identified in E. alsodes that would render the encoded perA gene nonfunctional.

Aspergillus luchuensis is known as an industrially important fungal species used for making fermented foods such as awamori and shochu in Japan, makgeolli and Meju in Korea, and Pu-erh tea in China. Nonetheless, this species has not yet been widely studied regarding mating-type genes. In this study, we examined the MAT1-1 and MAT1-2 gene ratio in black koji molds (A. luchuensis, Aspergillus niger, and Aspergillus tubingensis) and in Aspergillus welwitschiae isolated from Meju, a fermented soybean starting material for traditional soy sauce and soybean paste in Korea. The number of strains with the MAT1-1 locus was 2 of 23 (A. luchuensis), 6 of 13 (A. tubingensis), 21 of 28 (A. niger), and 5 of 10 (A. welwitschiae). Fungal species A. tubingensis and A. welwitschiae showed a 1 : 1 ratio of MAT1-1 and MAT1-2 mating-type loci. In contrast, A. luchuensis revealed predominance of MAT1-2 (91.3%) and A. niger of MAT1-1 (75%). We isolated and identified 2 A. luchuensis MAT1-1 strains from Meju, although all strains for making shochu in Japan are of the MAT1-2 type. These strains may be a good resource for breeding of A. luchuensis to be used in the Asian fermented-food industry.

Verticillium wilt of sugar beet is a disease that has received very little attention, but which has been reported to reduce sugar quality. A survey of sugar beet fields with wilt symptoms was conducted in 2007 (5 roots from each of 40 fields) and 2008 (5 roots from each of 45 fields) in Idaho. Verticillium dahliae was isolated from all root samples. From a collection of 106 V. dahliae sugar beet isolates, all were of the MAT1-2 mating type. The vegetative compatibility grouping (VCG) was evaluated for 93 of these isolates and 95, 3, 1 and 1% were VCG 4A, VCG 2B, VCG 4B and non-compatible, respectively. All the VCG 4A isolates had the same mitochondrial haplotype based on sequencing of cox3 to nad6 and cox1 to rnl loci, while the VCG 2B isolates had two haplotypes. Pathogenicity tests on sugar beet cultivar ‘Monohikari’ revealed that the VCG 4A isolates produced more foliar symptoms (P

The crop destroyer Phytophthora uses mating hormones α1 and α2 to commence its sexual reproduction. The α1-induced sexual reproduction of the A2 mating type was unexpectedly found to be interfered with by the counterhormone α2 that the A2 type itself produces to induce the sexual reproduction of the A1 type. A plausible mechanism is proposed based on structure–activity relationships.

Producción Científica, Fifteen families of mycoviruses have been described and 80% of these catalogued. However, their evolutionary relationship with fungi is not clear. The mycovirus genome can be formed by single- or double-stranded RNA or single-stranded DNA. The effects of mycoviruses range from the induction of a cryptic state (asymptomatic) to promotion of hyper- or hypovirulence in the host. Horizontal transmission of mycoviruses is determined by the presence of different vegetative compatibility types and mating types. Biocontrol of chestnut blight (Cryphonectria parasitica) has been found to be a successful mycovirus-based treatment and is considered a model in forest disease management. Development of this type of biological control tool for use in other forest pathologies requires a sound knowledge of viral symptomatology and transmission. The present review focuses on the application of mycoviruses and the prospects for future use in the biological control of forest diseases as well as on advances in mycovirus-applied research in forestry, landscape and culture of woody plants., Ministerio de Economía, Industria y Competitividad (Project AGL2012-39912)

Item does not contain fulltext Talaromyces amestolkiae is a common cosmopolitan species that has been cultured from indoor house dust, sputum and lungs from cystic fibrosis patients, indoor air, wheat, soil, pineapple, sculptures and manure. It was described as an asexual Talaromyces species and was reported to produce black sclerotia. In this study we report on the induction of sexual reproductive structures in T. amestolkiae. The mating type of 18 T. amestolkiae strains was determined with MAT-specific primers. Subsequently opposite mating types were inoculated on oatmeal agar and malt-extract agar and incubated 6-20 wk at 25 and 30 C in darkness. After incubation single ascospore isolations were made and evidence of recombination in the offspring was examined by amplified fragment length polymorphism and pairwise homoplasy index test, which is implemented in Splitstree4. The offspring displayed clear evidence of recombination on a genetic level as shown in the variations observed between banding patterns in the amplified fragment length polymorphism. Also a net-like and reticulated NeighborNet was observed and the pairwise homoplasy index test for recombination supported the presence of recombination (P = 0.003372). The distribution of MAT1-1 and MAT1-2 genes in the progeny showed a close to 1:1 ratio. Talaromyces amestolkiae is only the second heterothallic Talaromyces species to produce ascomata and ascospores under laboratory conditions.

The fungus Pyrenophora teres Drechs. occurs as two morphologically similar but genetically distinct forms, P. teres f. teres (Ptt) and P. teres f. maculata (Ptm), which cause the net form and spot form of net blotch of barley, respectively. A collection of 220 isolates from the Canadian prairie provinces (Alberta, Saskatchewan and Manitoba) was evaluated for mating type (MAT) idiomorph distribution and frequency. Fungal isolates were classified as Ptt or Ptm using form-specific polymerase chain reaction (PCR) primers. PCR analysis with MAT-specific primers indicated that the MAT1 and MAT2 idiomorphs of Ptt and Ptm could be identified within the same field, on the same plant, and on the same leaf. There was no significant departure from the expected 1:1 MAT1/MAT2 ratio for both forms in all three provinces or in the Canadian prairies population as a whole. Polymorphic simple sequence repeat primers were used to detect evidence of possible recombination between the two forms. Cluster analysis reveal...

The genus Ulocladium is thought to be strictly asexual. Mating-type (MAT) loci regulate sexual reproduction in fungi and their study may help to explain the apparent lack of sexual reproduction in Ulocladium. We sequenced the full length of two MAT genes in 26 Ulocladium species and characterized the entire MAT idiomorphs plus flanking regions of Ulocladium botrytis. The MAT1-1 ORF encodes a protein with an alpha-box motif by the MAT1-1-1 gene and the MAT1-2 ORF encodes a protein with an HMG box motif by the MAT1-2-1 gene. Both MAT1-1-1 and MAT1-2-1 genes were detected in a single strain of every species. Moreover, the results of RT-PCR revealed that both MAT genes are expressed in all 26 Ulocladium species. This demonstrates that MAT genes of Ulocladium species might be functional and that they have the potential for sexual reproduction. Phylogenies based on MAT genes were compared with GAPDH and Alt a 1 phylograms in Ulocladium using maximum parsimony (MP) and Bayesian analysis. The MAT genealogies and the non-MAT trees displayed different topologies, indicating that MAT genes are unsuitable phylogenetic markers at the species level in Ulocladium. Furthermore, the conflicting topologies between MAT1-1-1 and MAT1-2-1 phylogeny indicate separate evolutionary events for the two MAT genes. However, the intergeneric phylogeny of four closely allied genera (Ulocladium, Alternaria, Cochliobolus, Stemphylium) based on MAT alignments demonstrated that MAT genes are suitable for phylogenetic analysis among allied genera.

Fusarium tucumaniae is the only known sexually reproducing species among the seven closely related fusaria that cause soybean sudden death syndrome (SDS) or bean root rot (BRR). In a previous study, laboratory mating of F. tucumaniae yielded recombinant ascospore progeny but required two mating-compatible strains, indicating that it is heterothallic. To assess the reproductive mode of the other SDS and BRR fusaria, and their potential for mating, whole-genome sequences of two SDS and one BRR pathogen were analyzed to characterize their mating type (MAT) loci. This bioinformatic approach identified a MAT1-1 idiomorph in F. virguliforme NRRL 22292 and MAT1-2 idiomorphs in F. tucumaniae NRRL 34546 and F. azukicola NRRL 54364. Alignments of the MAT loci were used to design PCR primers within the conserved regions of the flanking genes APN1 and SLA2, which enabled primer walking to obtain nearly complete sequences of the MAT region for six MAT1-1 and five MAT1-2 SDS/BRR fusaria. As expected, sequences of the highly divergent 4.7 kb MAT1-1 and 3.7 kb MAT1-2 idiomorphs were unalignable. However, sequences of the respective idiomorphs and those that flank MAT1-1 and MAT1-2 were highly conserved. In addition to three genes at MAT1-1 (MAT1-1-1, MAT1-1-2, MAT1-1-3) and two at MAT1-2 (MAT1-2-1, MAT1-2-3), the MAT loci of the SDS/BRR fusaria also include a putative gene predicted to encode for a 252 amino acid protein of unknown function. Alignments of the MAT1-1-3 and MAT1-2-1 sequences were used to design a multiplex PCR assay for the MAT loci. This assay was used to screen DNA from 439 SDS/BRR isolates, which revealed that each isolate possessed MAT1-1 or MAT1-2, consistent with heterothallism. Both idiomorphs were represented among isolates of F. azukicola, F. brasiliense, F. phaseoli and F. tucumaniae, whereas isolates of F. virguliforme and F. cuneirostrum were only MAT1-1 and F. crassistipitatum were only MAT1-2. Finally, nucleotide sequence data from the RPB1 and RPB2 genes were used to date the origin of the SDS/BRR group, which was estimated to have occurred about 0.75 Mya (95% HPD interval: 0.27, 1.68) in the mid-Pleistocene, long before the domestication of the common bean or soybean.

Taro (Colocasia esculenta) is an important food crop, and taro leaf blight caused by Phytophthora colocasiae can significantly affect production. Our objectives were to develop single nucleotide polymorphism (SNP) markers for P. colocasiae and characterize populations in Hawaii (HI), Vietnam (VN) and Hainan Island, China (HIC). In total, 379 isolates were analyzed for mating type and multilocus SNP profiles including 214 from HI, 97 from VN and 68 from HIC. A total of 1152 single nucleotide variant (SNV) sites were identified via restriction site-associated DNA (RAD) sequencing of two field isolates. Genotyping with 27 SNPs revealed 41 multilocus SNP genotypes grouped into seven clonal lineages containing 2-232 members. Three clonal lineages were shared among countries. In addition, five SNP markers had a low incidence of loss of heterozygosity (LOH) during asexual laboratory growth. For HI and VN, >95% of isolates were the A2 mating type. On HIC, isolates within single clonal lineages had A1, A2 and A0 (neuter) isolates. The implications for the wide dispersal of clonal lineages are discussed.

Ascochyta blight, caused by Ascochyta rabiei is the most destructive disease of aerial parts of chickpea (Cicer arietinum L.) worldwide. Forty isolates of A. rabiei representing eight geographical regions, were collected from the west and south western Iran, and analysed for mating type distribution and fertility. A multiplex PCR assay using specific primers designed to amplify partial regions of the MAT1–1 and MAT1–2 idiomorphs was used to facilitate population analysis. Didymella rabiei populations were dominated by MAT1–1 mating type. The fertility status of isolates was determined using controlled crosses in vitro, pairing each isolate with compatible standard testers (USDA-AR-20 and USDA-AR21). Out of the 40 tested isolates, 38 isolates (95%) were MAT1–1 and two isolates (5%) were MAT1–2. Both mating types were present in Gachsaran and Jalian Populations, where Chi-square tests showed the proportions of each mating type were significantly different from 1:1 ratio. The predominance of one mating type ...

The process of mating in Basidiomycota is regulated by homeodomain-encoding genes (HD) and pheromones and G protein-coupled pheromone receptor genes (P/R). Whether these genes are actually involved in determining mating type distinguishes mating systems that are considered tetrapolar (two locus) from bipolar (one locus). Polyporales are a diverse group of wood-decay basidiomycetes displaying high variability in mating and decay systems. Many of the bipolar species appear to be brown-rot fungi, and it has been hypothesized that there is a functional basis for this correlation. Here we characterize mating genes in recently sequenced Polyporales and other Agaricomycete genomes. All Agaricomycete genomes encode HD and pheromone receptor genes regardless of whether they are bipolar or tetrapolar. The HD genes are organized into a MAT-HD locus with a high degree of gene order conservation among neighboring genes, with the gene encoding mitochondrial intermediate peptidase consistently syntenic but no linkage to the P/R genes. To have a complete dataset of species with known mating systems we determined that Wolfiporia cocos appears to be bipolar, using the criterion that DNA polymorphism of MAT genes should be extreme. Testing the correlation of mating and decay systems while controlling for phylogenetic relatedness failed to identify a statistical association, likely due to the small number of taxa employed. Using a phylogenetic analysis of Ste3 proteins, we identified clades of sequences that contain no known mating type-specific receptors and therefore might have evolved novel functions. The data are consistent with multiple origins of bipolarity within the Agaricomycetes and Polyporales, although the alternative hypothesis that tetrapolarity and bipolarity are reversible states needs better testing.

Detection of mating type (MAT) in fungi is very important for a better understanding of fungal biology, reproduction, and pathogenicity. Here we describe a new PCR-based identification of mating ty...

The planktonic diatom Fragilariopsis kerguelensis plays an important role in the biogeochemical cycles of the Southern Ocean, where remains of its frustules form the largest deposit of biogenic silica anywhere in the world. We assessed the genetic identity of 26 strains, from cells collected at various sites in the Southern Ocean, using three molecular markers, LSU and ITS rDNA and rbcL. The LSU sequences were identical among the tested strains, ITS sequences were highly similar, and only one base pair difference was detected among the rbcL sequences. These results, together with a large number of successful mating experiments demonstrated that the strains belong to a single biological species. We investigated the mating system and life cycle traits of F. kerguelensis. Cell size diminished gradually in clonal strains. Gamete formation only occurred when strains of opposite mating type – within a cell size range of 7–36 µm – were mixed together. Two binucleate gametes were formed in each gametangium and ga...

Aspergillus terreus has a worldwide distribution in soil, constitutes the third most important cause of invasive aspergillosis in humans and is classically regarded as a strictly asexual species. Strains of A. terreus were characterized by ITS, β-tubulin and calmodulin sequences. Mating type was identified by amplifying and sequencing MAT1-1 and MAT1-2 genes. One MAT1-2 strain produced hyphal masses when crossed with four MAT1-1 strains on mixed cereal agar after 3 wk at 37 C. Cleistothecia formed inside the hyphal masses and produced asci containing smooth-walled ascospores with an equatorial protuberance. This is the first report of sexual reproduction in A. terreus.

Fusarium tupiense, the main causal agent of mango malformation in Brazil, is described through a combination of morphological, biological and molecular markers. This new species belongs to the Gibberella fujikuroi species complex (GFSC) and has an anamorph morphologically similar to Fusarium mangiferae and F. sterilihyphosum. F. tupiense can be differentiated from other species in the G. fujikuroi species complex on the basis of sexual crosses, amplified fragment length polymorphism (AFLP) markers and partial sequences of the tef1 and tub2 genes. Female fertility for field isolates of F. tupiense appears to be low. PCR with primers specific for the mating type (MAT) alleles and sexual crosses identified this species as heterothallic with two idiomorphs. Female-fertile tester strains were developed for the identification of field strains of this species through sexual crosses.

In the genus Glomerella all species studied to date do not fit the usual mating system of heterothallic ascomycetes. This study investigated the mating system of G. truncata (anamorph Colletotrichum truncatum), a pathogen responsible for lentil anthracnose. Twenty-two field isolates from the Canadian prairies were crossed in all possible combinations, including selfings. All isolates also were screened for the presence of the MAT1-1 and MAT1-2 idiomorphs by targeting small conserved areas of the MAT genes (the alpha domain and the high mobility group HMG box) with degenerate primers, and a pair of G. truncata-specific HMG primers (CT21HMG) were designed. The results of the classical mating study suggested that G. truncata is heterothallic. Isolates fell into two incompatibility groups, which is consistent with a bipolar mating system but different from what has been described in other Glomerella species. Molecular screening showed that the HMG box used as a marker for the MAT1-2 idiomorph was present in both partners of fertile crosses in G. truncata, unlike in the typical ascomycete system, but as previously described for two other Glomerella species. G. truncata therefore appears to share unusual mating system characteristics with the other Glomerella species studied to date.

Complete mitochondrial genome of Phytophthora infestans, A2 mating type (MT) with a size of ≅37,767 bp was sequenced. A total of 53 protein-coding genes are predicted on both strands, including 25 tRNA, 2 rRNA, and 18 respiratory proteins. Gene order of A2MT was consistent with that established in A1, despite high level of polymorphism in both coding and non-coding regions. The mtDNA of A2MT was found to have 99.5% and 99.4% homology with Ia and Ib, whereas 94.7% and 94.3% with IIa and IIb, respectively. Study of repeats revealed a dinucleotide (AT)9 specific to A1 and homology of cox1 gene sequence revealed the relationship among 50 Phytophthora species.

The effects of temperature regimes on the radial growth rate of different isolates of Ascochyta lentis and pathogen virulence and host susceptibility were studied in the laboratory and growth chamber using different pathogen isolates, and lentil genotypes with varying levels of resistance to Ascochyta blight. The growth rate of most isolates increased as temperature increased up to 20°C and declined thereafter. In experiment 1, the highest disease severities were observed on cvs. Laird and Eston and the lowest on ILL5588. Mean disease severities were similar from 10 to 20°C but substantially lower at 25°C for all genotypes except ILL5588. In experiment 2, no significant differences were observed between the two mating types, or in their interactions with genotypes and temperatures. The interactions of genotypes with temperature and with isolates indicated that the relative susceptibility of lentil genotypes depended on temperature and on the isolates of A. lentis. These findings indicated that when temper...

Root rot, caused by Fusarium avenaceum (teleomorph: Gibberella avenacea), is an important disease of lupin (Lupinus angustifolius) and other crops in western Canada. Fusarium isolates collected from infected roots of lupin in central Alberta were characterized using two RAPD primers, three microsatellite-primed PCR markers, diagnostic primers for putative mating type, sequence comparison of the translation elongation factor 1α (EF1α) and internal transcribed spacer (ITS) region, and assessments of aggressiveness on lupin seedlings. The teleomorph phase of F. avenaceum has been reported only twice in the world, but both mating types were found throughout the province. Isolates of mating type 2 were slightly more aggressive than mating type 1 on five lupin cultivars. All 42 isolates of F. avenaceum assessed in this study had a unique multilocus genotype, which indicates a high level of genotypic diversity in the pathogen population. Cluster analysis did not reveal an association between the geograp...

Mann D.G. and PoulIckova A. 2010. Mating system, auxosporulation, species taxonomy and evidence for homoploid evolution in Amphora (Bacillariophyta). Phycologia 49: 183–201. DOI: 10.2216/09-08.1 Cytological characteristics of the mitotic cycle, sexual reproduction and auxospore formation are described for three members of the type group of Amphora: A. ovalis, A. copulata and A. minutissima. All have a single lobed ventral chloroplast, nuclei with granular heterochromatin and a single nucleolus (unusually large in A. ovalis). Amphora copulata is heterothallic, with two mating types that do not differ in gamete behaviour. All three species reproduce allogamously via fusion of two rearranged gametes per gametangium to produce elongate zygotes enclosed within the volume delimited by the gametangial thecae. Pairing is strictly via the ventral sides of the cells, with tight apposition of the cells, and expansion of the auxospores is strictly perpendicular to the gametangium long axes. Comparisons are m...

We have examined the hypothesis that the highly selective recombination of an active mating type locus (MAT) with either HMLalpha or HMRa is facilitated by the spatial positioning of relevant sequences within the budding yeast (Saccharomyces cerevisiae) nucleus. However, both position relative to the nuclear envelope (NE) and the subnuclear mobility of fluorescently tagged MAT, HML, or HMR loci are largely identical in haploid a and alpha cells. Irrespective of mating type, the expressed MAT locus is highly mobile within the nuclear lumen, while silent loci move less and are found preferentially near the NE. The perinuclear positions of HMR and HML are strongly compromised in strains lacking the Silent information regulator, Sir4. However, HMLalpha, unlike HMRa and most telomeres, shows increased NE association in a strain lacking yeast Ku70 (yKu70). Intriguingly, we find that the yKu complex is associated with HML and HMR sequences in a mating-type-specific manner. Its abundance decreases at the HMLalpha donor locus and increases transiently at MATa following DSB induction. Our data suggest that mating-type-specific binding of yKu to HMLalpha creates a local chromatin structure competent for recombination, which cooperates with the recombination enhancer to direct donor choice for gene conversion of the MATa locus.

Leaf blight and corm rot caused by Phytophthora colocasiae are the most devastating diseases of taro. Oospores of P. colocasiae have not been considered important in the survival in natural soil because the pathogen is heterothallic and there is essentially no chance for the presence of both A1 and A2 mating types in the same host tissue. During our recent survey of the mating type distribution of P. colocasiae in Taiwan seven homothallic isolates of Phytophthora were obtained from diseased taro leaves at Tsu Chi in central Taiwan. These organisms were identified as P. colocasiae based on morphological characteristics, ITS sequence homology and pathogenicity to taro plants. The homothallic isolates of P. colocasiae segregated into A1 and A2 types in addition to the original A1A2 type during asexual reproduction and vegetative growth. The homothallic isolate and the mixture of its A1 and A2 segregants produced abundant oospores in live tissue of taro petioles on or away from soil, indicating the possibility of oospores as a survival structure and the source of genetic variation in certain areas in nature.

Fifty-one isolates of Phytophthora cinnamomi isolated from ornamental plants in South Carolina, USA, between 1995 and 2000 were characterized by sporangium morphology, mating type, sensitivity to the fungicide mefenoxam, fatty acid methyl ester (FAME) profile analysis, and amplified fragment length polymorphism (AFLP) analysis. Sporangium shapes were predominantly ovoid to ellipsoid, and size averaged 65.5×40.3 μm (length×breadth) with average length/breadth ratio of 1.6. Forty-nine isolates were the A2 mating type with only two A1 isolates found. This is the first report of the A1 mating type of P. cinnamomi in South Carolina. All isolates were sensitive to mefenoxam and EC50 values for all isolates were less than 0.2 μg ml−1. FAMEs of each isolate were analysed by gas chromatography and revealed five major fatty acids: myristic (14:0), palmitic (16:0), linoleic (18:2ω6c), oleic (18:1ω9c), and eicosapentaenoic (20:5ω3c) acids. These five fatty acids accounted for more than 80% of FAME profiles. ...

Four hundred and sixty-nine Septoria passerinii isolates sampled from 15 widely distributed fields in North Dakota and two in western Minnesota were used to analyze the distribution and frequency of mating type idiomorphs using a multiplex polymerase chain reaction. Two sites, Williston, North Dakota, and Langdon, North Dakota, were sampled in a hierarchical fashion, and the remaining 15 sites were sampled in a random stratified fashion. The χ2 test revealed that, with clone-corrected data, equal frequencies of both mating types occurred within the whole field at both Williston and Langdon as well as at 11 of 15 sites sampled with a random stratified method. Only one of the two mating types was found at each of four sites. In two of those sites, this finding could have resulted from small sample sizes rather than evolutionary forces. Equal frequencies of the two mating types are consistent with a sexually reproducing population. From the results of this study, we conclude that, despite a teleomorph never ...

The genome of the honeybee fungal pathogen Ascosphaera apis (Maassen) encodes three putative high mobility group (HMG-box) transcription factors. The predicted proteins (MAT1-2, STE11 and HTF), each of which contain a single strongly conserved HMG-box, exhibit high similarity to mating type proteins and STE11-like transcription factors previously identified in other ascomycete fungi, some of them important plant and human pathogens. In this study we characterized the A. apis HMG-box containing genes and analyzed the structure of the mating type locus (MAT1-2) and its flanking regions. The MAT1-2 locus contains a single gene encoding a protein with an HMG-box. We also have determined the transcriptional patterns of all three HMG-box containing genes in both mating type idiomorphs and discuss a potential role of these transcription factors in A. apis development and reproduction. A multiplex PCR method with primers amplifying mat1-2-1 and Ste11 gene fragments is described. This new method allows for identification of a single mating type idiomorph and might become an essential tool for applied and basic research of chalkbrood disease in honeybees.

In this study, subtractive PCR was used to isolate a gene that is differentially expressed in the different mating-type cells of Alexandrium tamarense. After three rounds of subtractive PCR using c...

Clonal cultures of Pseudo-nitzschia pungens were isolated at various times from seven sites in the North Sea. During the mitotic cell cycle, the two plate-shaped chloroplasts were girdle-appressed during interphase and mitosis. After cytokinesis, the chloroplasts moved onto the parental valve and remained there during the formation of the new hypovalve and until separation and re-arrangement of the sibling cells within the cell chain had been completed. Clones were almost always heterothallic and cultures of opposite mating type isolated from different localities were compatible. Meiosis I was cytokinetic and accompanied by chloroplast division. Meiosis II involved karyokinesis but not cytokinesis and preceded the rearrangement and contraction of the two gametes. Sexual reproduction involved physiological anisogamy. With one exception, gamete behaviour was clone-specific, gametes being active in clones of one mating type but passive in clones of the other mating type. Auxospore development was accompanied...

D.G. MANN AND V.A. CHEPURNOV. 2005. Auxosporulation, mating system, and reproductive isolation in Neidium (Bacillariophyta). Phycologia 44: 335‐350. Three allogamous Neidium demes, referrable to N. ampliatum sensu lato,coexist without intergradation in Blackford Pond, Edinburgh, and some other lakes. A slight change in valve shape has occurred in one deme during the last 20 years. Morphological deme traits persist in healthy clonal cultures, but with time or during senescence, aberrant morphologies and sizes of cell can be produced that have no parallel in nature. Simplification of valve outline occurs as cells get smaller, but the initial cells also have a simplified morphology. The rostrate apices of some N. ampliatum demes develop rapidly after auxosporulation, during the first divisions of the initial cells. The ‘major’ and ‘minor’ demes of N. ampliatum are heterothallic, although some inbreeding occurs. Very rarely, mixed pairs of ‘major’ 3 ‘minor’ are formed, but hybrid auxospores are apparently never produced, so the demes are reproductively isolated. The ‘maternal’ gametangium has a nongenetic influence on initial cell size; however, the effect is slight and control of initial cell size is very well buffered to variation in gametangium size, so the concept of ‘cardinal points’ is valid for this species complex. The characteristics of sexual reproduction in clones and seminatural populations (including the effective, though incomplete, suppression of triplets and larger groups during copulation) prompt hypotheses about pairing mechanisms, in particular that a chemoattractant is involved. Preferential polyandry in Sellaphora and theoretical considerations indicate that the chemoattractant is produced by only one mating type. Size selection of mates in the ‘minor’ deme probably reflects progressively easier and more rapid sexualization as cells become smaller.

The development of advanced molecular diagnosis for the critical toxigenic Fusarium species is considered in this review. The specific topics discussed are ( 1) isolation of mating type genes of Gibberella complex, ( 2) molecular detection of Fusarium-producing fumonisins, ( 3) molecular detection of Fusarium-producing trichothecenes and enniatins. Particular attention is given to the development of PCR assays for genes involved in the toxin biosynthesis that would permit the early detection of Fusarium species-producing toxins and potentially even reveal which particular toxin may be present within a food or feed product. Most of these data have been obtained within the 'De-Tox Fungi' project supported by the European Commission (QLK1-CT-1998-01380).

Filament and gamete morphology, mating tests and hybridizations reveal the presence of eight taxa of Urospora from the Pacific and Atlantic coasts of North America. Three are dioecious and anisogamous: U. penicilliformis, U. neglecta and U. wormskioldii (synonym: U. vancouveriana). A fourth, U. bangioides, is monoecious and isogamous. Two are unisexual female variants, one with biflagellate parthenogametes (both coasts) and the other with quadriflagellate parthenogametes (Atlantic coast only). Two others are unidentified monoecious, anisogamous variants: one on the Atlantic coast and one on the Pacific coast. Urospora penicilliformis, U. neglecta and U. wormskioldii from the Pacific formed viable hybrids with their Atlantic counterparts and are considered to be conspecific with them. Urospora penicilliformis from the Pacific coast also formed viable hybrid zygotes with U. penicilliformis from Helgoland and Japan, again indicating conspecificity. On the Pacific coast, U. penicilliformis is the mos...

Candida albicans, the most prevalent fungal pathogen of humans, has recently been shown to undergo mating. Here we describe a mating pheromone produced by C. albicans alpha cells and show that the gene which encodes it (MFalpha) is required for alpha cells, but not a cells, to mate. We also identify the receptor for this mating pheromone as the product of the STE2 gene and show that this gene is required for the mating of a cells, but not alpha cells. Cells of the a mating type respond to the alpha mating pheromone by producing long polarized projections, similar to those observed in bona fide mating mixtures of C. albicans a and alpha cells. During this process, transcription of approximately 62 genes is induced. Although some of these genes correspond to those induced in Saccharomyces cerevisiae by S. cerevisiae alpha-factor, most are specific to the C. albicans pheromone response. The most surprising class encode cell surface and secreted proteins previously implicated in virulence of C. albicans in a mouse model of disseminated candidiasis. This observation suggests that aspects of cell-cell communication in mating may have been evolutionarily adopted for host-pathogen interactions in C. albicans.

The genetic control of aggressiveness in Phytophthora infestans to tomato was investigated by analyzing hybrid progeny from five different crosses (four F1 crosses and one F2 cross). The parental isolates were all highly aggressive to potatoes, but some had low and others had high aggressiveness to tomato. Of 225 single-oospore progenies tested, 198 were demonstrated to be recombinants on the basis of mating type, allozyme genotype, and (in some cases) nuclear-DNA fingerprint. Trisomy for some parental and progeny isolates was suggested from analysis of allozyme data. The recombinants were evaluated for aggressiveness using detached leaflets of both tomato and potato. From these assays, we suggest that there is a locus with strong influence on P. infestans aggressiveness to tomato, with low aggressiveness being dominant. Other loci of less influence may also be involved, but were not detectable. Some progenies were not aggressive to potatoes, which was consistent with the hypothesis that aggressiveness to...

A leaf and twig blight disease of Buxus spp. was found to be associated with a new species of Cylindrocladium. The novel species status was confirmed using morphological characters, sequencing of the ribosomal 5.8S RNA gene and the flanking internal transcribed spacers (ITS), the β-tubulin gene, and the high mobility group (HMG) of the MAT2 mating type gene. Cylindrocladium buxicola is proposed as a new name. Fifteen isolates from the UK and one isolate from New Zealand were paired in all combinations but no fertile perithecia were obtained suggesting that C. buxicola is heterothallic and all isolates belonged to one mating type. AFLP analysis showed that the isolates collected in the UK and New Zealand are genetically homogenous. Phylogenetic analyses indicated that this species falls within a new lineage.

Gibberella pulicaris (anamorph: Fusarium sambucinum), is a common potato pathogen that produces trichothecene mycotoxins and reduces plant yield and tuber quality. Field isolates have been recovered from western Canada that are resistant to thiabendazole, a benzimidazole fungicide registered in many countries to control dry rot in storage. To characterize this resistance, homokaryons were derived from single ascospores that were produced in vitro from crosses of thiabendazole-resistant G. pulicaris field isolates with sensitive isolates of an opposite mating type. The β-tubulin gene was amplified from these homokaryons using degenerate oligonucleotides synthesized to conserved sequences of the β-tubulin gene derived from related fungi. An open reading frame containing three putative introns and a deduced amino acid sequence of 446 amino acids exhibited a high level of homology to the β-tubulin gene of other fungi. Although nucleotide and amino acid differences were observed in the β-tubulin gene, none wer...

Blackleg of crucifers caused by Leptosphaeria maculans is the most important disease of broccoli and cauliflower in central Mexico, causing up to 70% yield loss in cauliflower crops. The pathogen was isolated from broccoli crops near Aguascalientes, Ags., and Zacatecas, Zac., and culture characteristics and pathogenicity on cauliflower were examined. Colony appearance and mycelial growth on V8-juice agar, germ tube growth on water agar, and the absence of pigment production in Czapek-Dox medium were characteristic of isolates belonging to the aggressive strain. No pseudothecia formed when the Mexican isolates were paired nor when they were crossed with a tester isolate for mating type +, suggesting that all of the Mexican isolates were of mating type +. This was indirectly confirmed by the absence of the MAT-2 gene, which is associated with mating type –. Reliable inoculation techniques, based on inoculation of wounded plants with pycnidiospores, were developed for cauliflower. In seedlings whose cotyledo...