scholarly journals First description of the sexual stage ofVenturia effusa, causal agent of pecan scab

2019 ◽  
Author(s):  
Nikki D. Charlton ◽  
Mihwa Yi ◽  
Clive H. Bock ◽  
Minling Zhang ◽  
Carolyn A. Young
Keyword(s):  
Mating Type ◽  
Culture Media ◽  
Spatial Scales ◽  
Sexual Cycle ◽  
Economic Losses ◽  
Mating Types ◽  
Sexual Stage ◽  
Pecan Scab ◽  
Prevalent Disease ◽  
The Impact

ABSTRACTVenturia effusa, cause of pecan scab, is the most prevalent disease of pecan in the southeastern USA; epidemics of the disease regularly result in economic losses to the pecan industry. Recent characterization of the mating type distribution revealed the frequency of theMATidiomorphs are in equilibrium at various spatial scales, indicative of regular sexual recombination. However, the occurrence of the sexual stage ofV. effusahas never been observed, and the pathogen was previously believed to rely entirely on asexual reproduction. To explore the existence of a sexual cycle, we paired opposite mating types on oatmeal culture media. In initial experiments, cultures were incubated at 24 C for 2 mo for hyphal interactions to occur between mating types and then maintained at 4 C for 4 mo. Immature pseudothecia were initially observed but following exposure to a 12 h photoperiod for 2 weeks at 24 C, asci and ascospores developed. Further experiments explored the effect of time on pseudothecial development with 4 mo at 4 C as the optimal requirement. The results of this study demonstrate the heterothallic nature ofV. effusa.Following experiments investigated progeny from a sexual cross of an albino and a wild-type isolate. Evaluation of isolate pigmentation, mating type, and multilocus genotyping of single ascospore progeny provided evidence that recombination occurred within the sexual crosses. The impact of determining the source of the overwintering ascostroma will aid in management decisions to reduce the primary inoculum in the disease cycle.

scholarly journals Evidence for Sexual Reproduction: Identification, Frequency, and Spatial Distribution of Venturia effusa (Pecan Scab) Mating Type Idiomorphs

2018 ◽  
Vol 108 (7) ◽  
pp. 837-846 ◽  
Author(s):  
Carolyn A. Young ◽  
Clive H. Bock ◽  
Nikki D. Charlton ◽  
Chakradhar Mattupalli ◽  
Nick Krom ◽  
...  
Keyword(s):  
United States ◽  
Mating Type ◽  
Spatial Scales ◽  
Southeastern United States ◽  
Draft Genome ◽  
Apple Scab ◽  
Hypothetical Protein ◽  
Sexual Stage ◽  
Pecan Scab ◽  
Conserved Genes

Venturia effusa (syn. Fusicladium effusum), causal agent of pecan scab, is the most prevalent pathogen of pecan (Carya illinoinensis), causing severe yield losses in the southeastern United States. V. effusa is currently known only by its asexual (conidial) stage. However, the degree and distribution of genetic diversity observed within and among populations of V. effusa are typical of a sexually reproducing fungal pathogen, and comparable with other dothideomycetes with a known sexual stage, including the closely related apple scab pathogen, V. inaequalis. Using the mating type (MAT) idiomorphs from V. inaequalis, we identified a single MAT gene, MAT1-1-1, in a draft genome of V. effusa. The MAT1-1-1 locus is flanked by two conserved genes encoding a DNA lyase (APN2) and a hypothetical protein. The MAT locus spanning the flanking genes was amplified and sequenced from a subset of 14 isolates, of which 7 contained MAT1-1-1 and the remaining samples contained MAT1-2-1. A multiplex polymerase chain reaction screen was developed to amplify MAT1-1-1, MAT1-2-1, and a conserved reference gene encoding β-tubulin, and used to screen 784 monoconidial isolates of V. effusa collected from 11 populations of pecan across the southeastern United States. A hierarchical sampling protocol representing region, orchard, and tree allowed for analysis of MAT structure at different spatial scales. Analysis of this collection revealed the frequency of the MAT idiomorphs is in a 1:1 equilibrium of MAT1-1:MAT1-2. The apparent equilibrium of the MAT idiomorphs provides impetus for a renewed effort to search for the sexual stage of V. effusa. [Formula: see text] Copyright © 2018 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

scholarly journals Mating-Type Distribution and Genetic Diversity of Cercospora sojina Populations on Soybean from Arkansas: Evidence for Potential Sexual Reproduction

2013 ◽  
Vol 103 (10) ◽  
pp. 1045-1051 ◽  
Author(s):  
Hun Kim ◽  
Annakay D. Newell ◽  
Robyn G. Cota-Sieckmeyer ◽  
John C. Rupe ◽  
Ahmad M. Fakhoury ◽  
...  
Keyword(s):  
Sexual Reproduction ◽  
Mating Type ◽  
Spatial Scales ◽  
Genotypic Diversity ◽  
The United States ◽  
Economic Losses ◽  
Mating Types ◽  
Cercospora Sojina ◽  
Single Leaf ◽  
Corrected Data

Cercospora sojina causes frogeye leaf spot of soybean, which can cause serious economic losses in the United States. In this study, 132 C. sojina isolates were collected from six fields (from two counties, Cross and Crawford) in Arkansas. To determine mating type, a multiplex polymerase chain reaction assay was developed with primers specific for C. sojina. Of the 132 isolates, 68 isolates had the MAT1-1-1 idiomorph and 64 isolates had the MAT1-2 idiomorph; no isolates possessed both idiomorphs. Both mating types were present in a variety of spatial scales, including separate lesions on individual leaves. Clone-corrected data from eight microsatellites indicated that mating-type loci were present in approximately equal proportions in all populations analyzed, which suggests that Arkansas populations of C. sojina are undergoing cryptic sexual reproduction. All six populations evaluated had high genotypic diversity of 26 to 79%. In addition, among strains isolated from a single leaf, multiple and distinct haplotypes were associated with both mating types, supporting the hypothesis that sexual reproduction occurs within the populations. Most populations showed significant gametic disequilibrium but levels of disequilibrium were relatively low, particularly in populations from Crawford County. A low differentiation index (GST) was observed for all simple-sequence repeat markers across all populations. Furthermore, the value of G statistics between populations suggests that significant genetic exchange exists among the populations. Taken together, these results demonstrate that C. sojina populations from Arkansas are genetically diverse and most likely undergoing sexual reproduction.

scholarly journals Sexual Reproduction in the Citrus Black Spot Pathogen, Phyllosticta citricarpa

2017 ◽  
Vol 107 (6) ◽  
pp. 732-739 ◽  
Author(s):  
Nga T. Tran ◽  
Andrew K. Miles ◽  
Ralf G. Dietzgen ◽  
Megan M. Dewdney ◽  
Ke Zhang ◽  
...  
Keyword(s):  
Sexual Reproduction ◽  
Culture Media ◽  
Black Spot ◽  
Physical Contact ◽  
Sexual Cycle ◽  
Economic Losses ◽  
Type Locus ◽  
Citrus Black Spot ◽  
Phyllosticta Citricarpa ◽  
The Impact

Citrus black spot (Phyllosticta citricarpa) causes fruit blemishes and premature fruit drop, resulting in significant economic losses in citrus growing areas with summer rainfall across the globe. The mating type locus of P. citricarpa has recently been characterized, revealing the heterothallic nature of this pathogen. However, insight into the occurrence of mating and the impact of completing the sexual cycle of P. citricarpa was lacking. To investigate the occurrence and impact of sexual reproduction, we developed a method to reliably, and for the first time, produce ascospores of P. citricarpa on culture media. To demonstrate meiosis during the mating process, we identified recombinant genotypes through multilocus genotyping of single ascospores. Because the process of fertilization was not well understood, we experimentally determined that fertilization of P. citricarpa occurs via spermatization. Our results demonstrate that P. citricarpa is heterothallic and requires isolates of different MAT idiomorphs to be in direct physical contact, or for spermatia to fulfill their role as male elements to fertilize the receptive organs, in order to initiate the mating process. The impact of mating on the epidemiology of citrus black spot in the field is discussed.

scholarly journals Equal Distribution of Mating Type Alleles and the Presence of Strobilurin Resistance in Algerian Zymoseptoria tritici Field Populations

Plant Disease ◽  
2017 ◽  
Vol 101 (4) ◽  
pp. 544-549 ◽  
Author(s):  
Hayet Meamiche Neddaf ◽  
Lamia Aouini ◽  
Zouaoui Bouznad ◽  
Gert H. J. Kema
Keyword(s):  
Mating Type ◽  
Spatial Scales ◽  
Septoria Tritici Blotch ◽  
Septoria Tritici ◽  
High Yield ◽  
Mating Types ◽  
Zymoseptoria Tritici ◽  
Equal Distribution ◽  
Country Level ◽  
Mitochondrial Cytochrome B

Zymoseptoria tritici, the causal agent of septoria tritici blotch, is an important wheat pathogen responsible for high yield losses worldwide. The assessment of the distribution of both mating type idiomorphs was studied in several wheat-growing areas in North Algeria. Both mating types occurred at all spatial scales tested and showed an equal frequency distribution at the country level, with 53% for Mat1-1 and 47% for Mat1-2. At finer scales, co-occurrence of both mating types was found in 38% of leaves analyzed and 44% of the studied lesions. Additionally, efficacy reduction of strobilurin applications prompted us to study strobilurin resistance conferred by the G143A substitution in the mitochondrial cytochrome b gene, which was found for the first time in six strains. The results suggest that the Algerian Z. tritici population undergoes frequent sexual reproduction mirrored by co-occurrence of both mating types, which likely will rapidly increase the fraction of strobilurin-resistant isolates in the Algerian population, as has been shown in all other regions where strobilurin resistance surfaced.

scholarly journals Impact of Mating Type, Serotype, and Ploidy on the Virulence of Cryptococcus neoformans

2008 ◽  
Vol 76 (7) ◽  
pp. 2923-2938 ◽  
Author(s):  
Xiaorong Lin ◽  
Kirsten Nielsen ◽  
Sweta Patel ◽  
Joseph Heitman
Keyword(s):  
Cryptococcus Neoformans ◽  
Mating Type ◽  
Pathogenic Fungi ◽  
Mating Types ◽  
Type Locus ◽  
Virulence Potential ◽  
The Impact ◽  
Ad Hybrids

ABSTRACT Hybridization with polyploidization is a significant biological force driving evolution. The effect of combining two distinct genomes in one organism on the virulence potential of pathogenic fungi is not clear. Cryptococcus neoformans, the most common cause of fungal infection of the central nervous system, has a bipolar mating system with a and α mating types and occurs as A (haploid), D (haploid), and AD hybrid (mostly diploid) serotypes. Diploid AD hybrids are derived either from a-α mating or from unisexual mating between haploid cells. The precise contributions of increased ploidy, the effect of hybridization between serotypes A and D, and the combination of mating types to the virulence potential of AD hybrids have remained elusive. By using in vitro and in vivo characterization of laboratory-constructed isogenic diploids and AD hybrids with all possible mating type combinations in defined genetic backgrounds, we found that higher ploidy has a minor negative effect on virulence in a murine inhalation model of cryptococcosis. The presence of both mating types a and α in AD hybrids did not affect the virulence potential, irrespective of the serotype origin. Interestingly, AD hybrids with only one mating type behaved differently, with the virulence of αADα strains similar to that of other hybrids, while aADa hybrids displayed significantly lower virulence due to negative epistatic interactions between the Aa and Da alleles of the mating type locus. This study provides insights into the impact of ploidy, mating type, and serotype on virulence and the impact of hybridization on the fitness and virulence of a eukaryotic microbial pathogen.

scholarly journals Some evidence for skewed mating type distribution in Iranian populations of Rhynchosporium commune, the cause of barley scald disease

2016 ◽  
Vol 56 (3) ◽  
pp. 237-243 ◽  
Author(s):  
Mahdi Arzanlou ◽  
Kaivan Karimi ◽  
Fariba Mirabi
Keyword(s):  
Mating Type ◽  
Spatial Scales ◽  
Genotypic Diversity ◽  
Sexual Cycle ◽  
Pcr Assay ◽  
Unequal Distribution ◽  
Equal Distribution ◽  
Multiplex Pcr Assay ◽  
The World ◽  
Mating Type Genes

AbstractRhynchosporium commune(formerly known asRhynchosporium secalis), the causal agent of scald disease on barley, is known to spread asexually by splash dispersed conidia. However, there are multiple lines of evidence for the possibility of a clandestine sexual cycle occurrence in this species including extensive genotypic diversity, equal distribution of mating type alleles across the world and expression of mating type genes. In the current study, the potential for the occurrence of a sexual cycle amongst the Iranian population ofR. communewas assessed by analyzing distribution and frequency of the mating type alleles at both micro and macro-spatial scales. A total of 95 single-conidialR. communeisolates were obtained from different barley fields in Kurdistan province. Previously designed primers were applied in a multiplex PCR assay to study distribution and frequency of the mating type alleles within and between populations. Totally, 67 isolates were determined asMAT1-1and the remaining 28 isolates asMAT1-2throughout the sampling counties. The results obtained at a macro-spatial scale revealed that unlike Kamyaran county (bothMAT1-1andMAT1-2at an equal ratio), an unequal distribution of mating type genes was dominant amongR. communeisolates in both Mariwan and Dehgolan counties. Our findings support a predominantly asexual reproduction for Mariwan and Dehgolan counties and the possibility of sexual stage occurrence in Kamyarna county.

scholarly journals Species and Mating-Type Distribution of Tapesia yallundae and T. acuformis and Occurrence of Apothecia in the U.S. Pacific Northwest

2002 ◽  
Vol 92 (7) ◽  
pp. 703-709 ◽  
Author(s):  
G. W. Douhan ◽  
T. D. Murray ◽  
P. S. Dyer
Keyword(s):  
Pacific Northwest ◽  
Mating Type ◽  
Spatial Scales ◽  
Mating Types ◽  
Field Plot ◽  
Type Distribution ◽  
Predominant Species ◽  
Tapesia Yallundae ◽  
Wheat Stubble ◽  
The U.S

Eyespot of wheat is caused by the discomycete fungi Tapesia yallundae and T. acuformis. T. yallundae is considered the most important causal agent of the disease in this region but no apothecia of either species have been found in the U.S. Pacific Northwest (PNW). Two compatible isolates of T. yallundae from the PNW were used to inoculate a field plot in the fall of 1998 and apothecia developed in the spring and fall of 2000 on standing wheat stubble. In the spring of 2000, wheat stubble from eight naturally infected fields was examined for the presence of apothecia of T. yallundae and T. acuformis. Apothecia of T. acuformis were found in two fields but no apothecia of T. yallundae were found. This is the first report of apothecia of the eyespot pathogens occurring in the PNW. Species and mating-type distribution of T. yallundae and T. acuformis in the PNW were determined from 817 isolates collected from diseased wheat over 3 years at spatial scales ranging from within fields to across states. In all, 460 isolates were identified as T. yallundae and 357 isolates were identified as T. acuformis with MAT1-1/MAT1-2 ratios not significantly different from 1:1 based on χ2 tests at most scales tested. The apparent increase in frequency of T. acuformis from previous surveys may indicate a shift in the predominant species causing eyespot. The occurrence of apothecia under field conditions, along with the widespread distribution of mating types of both species, suggests that sexual reproduction may be occurring in both species.

scholarly journals The Frequencies and Spatial Distribution of Mating Types in Stagonospora nodorum Are Consistent with Recurring Sexual Reproduction

2006 ◽  
Vol 96 (3) ◽  
pp. 234-239 ◽  
Author(s):  
Rubik J. Sommerhalder ◽  
Bruce A. McDonald ◽  
Jiasui Zhan
Keyword(s):  
Mating Type ◽  
Spatial Scales ◽  
Polymerase Chain Reaction Amplification ◽  
Random Amplified Polymorphic Dna ◽  
Stagonospora Nodorum ◽  
Data Sets ◽  
Mating Types ◽  
Type Locus ◽  
Geographical Regions ◽  
Sexual Recombination

To test the hypothesis that Stagonospora nodorum undergoes regular cycles of sexual recombination, a total of 1,207 isolates sampled from 18 fields in 12 geographical regions in six countries on five continents were analyzed for mating type frequency and distribution using polymerase chain reaction amplification of the mating type locus. Restriction fragment length polymorphism and random amplified polymorphic DNA fingerprints were used to clone-correct the data sets. Both mating types were often found on the smallest spatial scales tested, including within the same lesion, the same leaf, and the same 1-m2 plot. In only one case out of the 18 fields tested was there a significant departure from the expected 1:1 ratio. Combining this result with previous data on the population structure of S. nodorum, we conclude that this pathogen undergoes regular cycles of sexual recombination in all regions we examined.

scholarly journals The unusual sexual preferences of a chlamydomonas mutant may provide insight into mating-type evolution.

Genetics ◽  
1991 ◽  
Vol 127 (1) ◽  
pp. 103-115 ◽  
Author(s):  
K P Van Winkle-Swift ◽  
D J Thuerauf
Keyword(s):  
Mating Type ◽  
Sexual Cycle ◽  
Common Denominator ◽  
Crossing Over ◽  
Mating Types ◽  
Chloroplast Gene ◽  
Sexual Preferences ◽  
Heterothallic Species ◽  
Chlamydomonas Monoica ◽  
Insight Into

Abstract Chlamydomonas monoica undergoes intraclonal mating-type differentiation (homothallism). Although the species differs in this regard from the more commonly studied heterothallic C. reinhardtii, cell-cell interactions and progression of the sexual cycle are similar for many homothallic and heterothallic species of the genus. Regulation of chloroplast gene transmission by the nuclear mating-type alleles (mt+ and mt-) is another common denominator for Chlamydomonas species studied thus far. We have previously reported the use of chloroplast inheritance patterns to identify mutants of C. monoica that have lost the potential to function as the mt+ mating-type. A similar screening procedure led to the isolation of an unusual mutant, mtl-3 whose phenotype is less readily explained. Chloroplast gene transmission patterns in crosses involving mtl-3 suggest that the mtl-3 strain mates preferentially as mt+. However, normal mating efficiencies and high zygospore viability are observed in clonal culture, indicating the unbiased production of functional opposite mating-types. By construction of appropriately marked strains we have been able to show that mtl-3 mt- gametes prefer the mt+ gametes of their own strain. A model is presented which invokes unequal crossing over between highly homologous flagellar agglutinin genes to account for the unusual properties of the mtl-3 strain and for the evolution of mating barriers within the genus.

scholarly journals Abundant Genetic Diversity and Extensive Differentiation among Geographic Populations of the Citrus Pathogen Diaporthe citri in Southern China

2021 ◽  
Vol 7 (9) ◽  
pp. 749
Author(s):  
Tao Xiong ◽  
Yating Zeng ◽  
Wen Wang ◽  
Pudong Li ◽  
Yunpeng Gai ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Southern China ◽  
Spatial Scales ◽  
Natural Populations ◽  
Citrus Fruit ◽  
Total Sample ◽  
Economic Losses ◽  
Common Disease ◽  
Mating Types ◽  
Ssr Loci

The fungal pathogen Diaporthe citri is a major cause of diseases in citrus. One common disease is melanose, responsible for large economic losses to the citrus fruit industry. However, very little is known about the epidemiology and genetic structure of D. citri. In this study, we analyzed 339 isolates from leaves and fruits with melanose symptoms from five provinces in southern China at 14 polymorphic simple sequence repeat (SSR) loci and the mating type idiomorphs. The genetic variations were analyzed at three levels with separate samples: among provinces, among orchards within one county, and among trees within one orchard. The five provincial populations from Fujian, Zhejiang, Jiangxi, Hunan, and Guizhou were significantly differentiated, while limited differences were found among orchards from the same county or among trees from the same orchard. STRUCTURE analysis detected two genetic clusters in the total sample, with different provincial subpopulations showing different frequencies of isolates in these two clusters. Mantel analysis showed significant positive correlation between genetic and geographic distances, consistent with geographic separation as a significant barrier to gene flow in D. citri in China. High levels of genetic diversity were found within individual subpopulations at all three spatial scales of analyses. Interestingly, most subpopulations at all three spatial scales had the two mating types in similar frequencies and with alleles at the 14 SSR loci not significantly different from linkage equilibrium. Indeed, strains with different mating types and different multilocus genotypes were frequently isolated from the same leaves and fruits. The results indicate that sexual reproduction plays an important role in natural populations of D. citri in southern China and that its ascospores likely represent an important contributor to citrus disease.

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