scholarly journals OCCURRENCE OF A2 MATING TYPE AND MICROMORPHOLOGY OF OOSPORES OF PHYTOPHTHORA INFESTANS IN GOLESTAN PROVINCE OF IRAN

2018 ◽  
Vol 30 (1) ◽  
pp. 37
Author(s):  
Amir Zolfaghary
Keyword(s):  
Mating Type ◽  
Potato Production ◽  
Hybrid Origin ◽  
Thin Wall ◽  
Mating Types ◽  
Inoculum Sources ◽  
Average Value ◽  
Sexual Recombination ◽  
Golestan Province ◽  
Very High

The aim of this study was to determine the mating types, origin and micromorphology of oospores of Ph. infestans isolated from the potato fields in Golestan province of Iran during 2014-16. In total, 197 isolates were assessed for mating type. The average frequencies of mating types A1 and A2 were 85.8 and 14.2% respectively. A2 mating type was found only from two regions. A total of 9 self-fertile isolates (5.3%), which only belonged to the A1 mating type were detected. The average value for oospore production index (OPI) within the interaction zone between the two isolates was estimated one (very low) in A1×A1 and four (very high) in A1×A2 crosses. Oospores of hybrid origin were observed in A1 ×A2 and self-fertile oospores only in A1 ×A1 paired cultures. Parthenogenetic oospores (without antheridia) were not observed in A1 ×A1 or A2 ×A2 paired cultures. The results of oospores micromorphology indicated that the antheridia in hybrid oospores were amphigynous and from half spheric to nearly spheric, almost hyaline, from 18.5-23.5 × 10.5-15.5 µm in size. Oogonia were nearly spheric from nacarat to brown in colour. The colour of the hybrid oospores varied from brown to dark-brown, spheric, varied from 25-35 µm in diameter with two thick walls with thickness of 2.5-5.5 µm. The self-fertile oospores were with a thin wall with thickness of 1.5 µm, spherical and varied from 40-60 µm in diameter. The monitoring of A1 and A2 mating type ratios of oospores are important to aid in the prediction of the extent of sexual recombination and thus the risk of long-lived oospores serving as primary inoculum sources in the main potato production regions.

scholarly journals Evidence for Sexual Recombination in Didymella tanaceti Populations, and Their Evolution Over Spring Production in Australian Pyrethrum Fields

2019 ◽  
Vol 109 (1) ◽  
pp. 155-168 ◽  
Author(s):  
Tamieka L. Pearce ◽  
Jason B. Scott ◽  
Stacey J. Pilkington ◽  
Sarah J. Pethybridge ◽  
Frank S. Hay
Keyword(s):  
Genetic Diversity ◽  
Mating Type ◽  
Sampling Period ◽  
Genotypic Diversity ◽  
Tan Spot ◽  
Late Winter ◽  
Linkage Equilibrium ◽  
Mating Types ◽  
Isolation Frequency ◽  
Sexual Recombination

Tan spot, caused by Didymella tanaceti, is one of the most important foliar diseases affecting pyrethrum in Tasmania, Australia. Population dynamics, including mating-type ratios and genetic diversity of D. tanaceti, was characterized within four geographically separated fields in both late winter and spring 2012. A set of 10 microsatellite markers was developed and used to genotype 774 D. tanaceti isolates. Isolates were genotypically diverse, with 123 multilocus genotypes (MLG) identified across the four fields. Fifty-eight MLG contained single isolates and Psex analysis estimated that, within many of the recurrent MLG, there were multiple clonal lineages derived from recombination. Isolates of both mating types were at a 1:1 ratio following clone correction in each field at each sampling period, which was suggestive of sexual recombination. No evidence of genetic divergence of isolates of each mating type was identified, indicating admixture within the population. Linkage equilibrium in two of the four field populations sampled in late winter could not be discounted following clone correction. Evaluation of temporal changes in gene and genotypic diversity identified that they were both similar for the two sampling periods despite an increased D. tanaceti isolation frequency in spring. Genetic differentiation was similar in populations sampled between the two sampling periods within fields or between fields. These results indicated that sexual reproduction may have contributed to tan spot epidemics within Australian pyrethrum fields and has contributed to a genetically diverse D. tanaceti population.

scholarly journals Formation of the phenotypic structure of Phytophthora infestans population in Poland during 1987-2001

2013 ◽  
Vol 55 (1) ◽  
pp. 389-400 ◽  
Author(s):  
Hanna Zarzycka ◽  
Sylwester Sobkowiak ◽  
Renata Lebecka ◽  
Beata Tatarowska
Keyword(s):  
Phytophthora Infestans ◽  
Virulence Factors ◽  
Mating Type ◽  
The Other ◽  
Mating Types ◽  
Polish Population ◽  
Other Hand ◽  
Sexual Recombination ◽  
Phenotypic Structure ◽  
High Level

The formation of phenotypic structure of <i>P.infestans</i> population in Poland was determined by analyzing 1603 isolates collected from 1987 to 2001. The race complexity, low at the beginning of experiment, has been increasing from year to year and reached in 2001 a high level 7,2 virulence factors per isolate. The single and less composed races dominating firstly in the population were replaced gradually by more composed races. The virulence factors 1, 2, 3, 4, 7 and 11 occurred most frequently, but factors 5 and 8 were noted sporadically. The A2 mating type was detected in 1988 at first and since that time its occurrence has been noted in Polish population each year. The oospores were formed in potato tissues. Race diversity, low at the beginning of the investigation, reached a peak in 1996-2001 . During 1987-1990 weakly and middly aggressive phenotypes dominated in Polish population. In the later period very aggressive isolates were more frequent. Phenotypic race similarity of <i>P.infestans</i> populations in 1987 and 2001 was very low. The race structure of 1987 population was totally different from the race structure of populations of the next years. It was probably due to migration of new pathotypes. On the other hand the variation in complexity, diversity and similarity of races, as well as in aggressiveness observed in later years of investigation can be caused by the presence of both mating types and sexual recombination.

scholarly journals Mating Types Analysis of Magnaporthe oryzae Populations by Molecular Methods

2014 ◽  
Vol 8 (1) ◽  
pp. 6-12 ◽  
Author(s):  
Soma Samanta ◽  
Urmila Dhua ◽  
Shubhransu Nayak ◽  
L. Behera ◽  
A. K. Mukherjee
Keyword(s):  
Mating Type ◽  
Ribosomal Rna ◽  
Magnaporthe Oryzae ◽  
Rice Blast ◽  
Population Diversity ◽  
Disease Spread ◽  
Mating Types ◽  
Type Analysis ◽  
Sexual Recombination ◽  
Rice Leaves

Rice blast is a devastating disease which is caused by the heterothallic fungus Magnaporthe oryzae. Compatible sexual recombination which occurs between two M. oryzae strains of different mating types, can enhance genetic variability. Assessment of mating type alleles is used as a marker to measure population diversity. Forty six isolates of M. oryzae were collected from infected rice leaves from various ecosystems of coastal Odisha, India, and the mating type analysis using molecular markers was carried out. MAT1-1 mating type was dominating in all the ecosystems and MAT1-2 was found to be present in uplands as well as in irrigated fields. Both mating types could be found in the same field in irrigated ecosystem. The disease spread was very fast vertically as well as horizontally in those fields resulting in blast lesions looking as ‘green islands (gi) produced in senescence leaves’, and MAT1-2 was found to be associated with all gi lesions. Consequently, the management of the disease in those plots was very difficult. Interestingly, ribosomal RNA IGS region could not be amplified in MAT1-2 isolates but consistent amplification was obtained in MAT1-1 mating type isolates.

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 Presence of α and a Mating Types in Environmental and Clinical Collections of Cryptococcus neoformans var. gattii Strains from Australia

1999 ◽  
Vol 37 (9) ◽  
pp. 2920-2926 ◽  
Author(s):  
C. L. Halliday ◽  
T. Bui ◽  
M. Krockenberger ◽  
R. Malik ◽  
D. H. Ellis ◽  
...  
Keyword(s):  
Cryptococcus Neoformans ◽  
Mating Type ◽  
Causative Agent ◽  
Pcr Primers ◽  
Mating Types ◽  
Limited Data ◽  
Environmental Isolates ◽  
Specific Pcr ◽  
Sexual Recombination ◽  
Mating Type Genes

Cryptococcus neoformans var. gattii lives in association with certain species of eucalyptus trees and is a causative agent of cryptococcosis. It exists as two mating types, MATα and MATa, which is determined by a single-locus, two-allele system. In the closely related C. neoformansvar. neoformans, the α mating type has been found to outnumber its a counterpart by at least 30:1, but there have been very limited data on the proportions of each mating type in C. neoformans var. gattii. In the present study, specific PCR primers were designed to amplify two separate α-mating-type genes from C. neoformans var.gattii strains. These were used to survey for the presence of the two mating types in clinical and environmental collections ofC. neoformans var. gattii strains from Australia. Sixty-eight of 69 clinical isolates produced both α mating type-specific bands and were assumed to be of the α mating type. The majority of environmental isolates were also of the α mating type, but the a mating type was located in two separate areas. In one area, the a mating type outnumbered the α mating type by 27:2, but in the second area, the ratio of the two mating types was close to the 50:50 ratio expected for sexual recombination.

scholarly journals Differential Gene Expression between Fungal Mating Types Is Associated with Sequence Degeneration

2020 ◽  
Vol 12 (4) ◽  
pp. 243-258 ◽  
Author(s):  
Wen-Juan Ma ◽  
Fantin Carpentier ◽  
Tatiana Giraud ◽  
Michael E Hood
Keyword(s):  
Differential Expression ◽  
Differentially Expressed Genes ◽  
Mating Type ◽  
Sex Chromosomes ◽  
Sex Chromosome ◽  
Gc Content ◽  
Differentially Expressed ◽  
Mating Types ◽  
Sexual Antagonism ◽  
Recombination Suppression

Abstract Degenerative mutations in non-recombining regions, such as in sex chromosomes, may lead to differential expression between alleles if mutations occur stochastically in one or the other allele. Reduced allelic expression due to degeneration has indeed been suggested to occur in various sex-chromosome systems. However, whether an association occurs between specific signatures of degeneration and differential expression between alleles has not been extensively tested, and sexual antagonism can also cause differential expression on sex chromosomes. The anther-smut fungus Microbotryum lychnidis-dioicae is ideal for testing associations between specific degenerative signatures and differential expression because 1) there are multiple evolutionary strata on the mating-type chromosomes, reflecting successive recombination suppression linked to mating-type loci; 2) separate haploid cultures of opposite mating types help identify differential expression between alleles; and 3) there is no sexual antagonism as a confounding factor accounting for differential expression. We found that differentially expressed genes were enriched in the four oldest evolutionary strata compared with other genomic compartments, and that, within compartments, several signatures of sequence degeneration were greater for differentially expressed than non-differentially expressed genes. Two particular degenerative signatures were significantly associated with lower expression levels within differentially expressed allele pairs: upstream insertion of transposable elements and mutations truncating the protein length. Other degenerative mutations associated with differential expression included nonsynonymous substitutions and altered intron or GC content. The association between differential expression and allele degeneration is relevant for a broad range of taxa where mating compatibility or sex is determined by genes located in large regions where recombination is suppressed.

scholarly journals Deletion of the Schizophyllum commune Aα Locus: The Roles of Aα Y and Z Mating-Type Genes

Genetics ◽  
1996 ◽  
Vol 144 (4) ◽  
pp. 1437-1444
Author(s):  
C Ian Robertson ◽  
Kirk A Bartholomew ◽  
Charles P Novotny ◽  
Robert C Ullrich
Keyword(s):  
Mating Type ◽  
Sexual Development ◽  
Schizophyllum Commune ◽  
Mating Types ◽  
Developmental Pathway ◽  
Mating Type Gene ◽  
Mating Type Genes ◽  
Regulatory Loci ◽  
Type Gene

The Aα locus is one of four master regulatory loci that determine mating type and regulate sexual development in Schizophyllum commune. We have made a plasmid containing a URA1 gene disruption of the Aα Y1 gene. Y1 is the sole Aα gene in Aα1 strains. We used the plasmid construction to produce an Aα null (i.e., AαΔ) strain by replacing the genomic Y1 gene with URA1 in an Aα1 strain. To characterize the role of the Aα genes in the regulation of sexual development, we transformed various Aα Y and Z alleles into AαΔ strains and examined the acquired mating types and mating abilities of the transformants. These experiments demonstrate that the Aα Y gene is not essential for fungal viability and growth, that a solitary Z Aα mating-type gene does not itself activate development, that Aβ proteins are sufficient to activate the A developmental pathway in the absence of Aα proteins and confirm that Y and Z genes are the sole determinants of Aα mating type. The data from these experiments support and refine our model of the regulation of A-pathway events by Y and Z proteins.

scholarly journals A PCR-based Assay for Distinguishing between A1 and A2 Mating Types of Phytophthora capsici

2017 ◽  
Vol 142 (4) ◽  
pp. 260-264
Author(s):  
Ping Li ◽  
Dong Liu ◽  
Min Guo ◽  
Yuemin Pan ◽  
Fangxin Chen ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Mating Type ◽  
Phytophthora Capsici ◽  
Mating Types ◽  
Sequence Repeat ◽  
Chain Reaction ◽  
Plant Parasite ◽  
Dna Fragment ◽  
Polymerase Chain ◽  
Microsatellite Diversity

Sexual reproduction in the plant parasite Phytophthora capsici Leonian requires the interaction of two distinct mating types, A1 and A2. Co-occurrence of these mating types can enhance the genetic diversity of P. capsici and alter its virulence or resistance characteristics. Using an intersimple sequence repeat (ISSR) screen of microsatellite diversity, we identified, cloned, and sequenced a novel 1121-base pair (bp) fragment specific to the A1 mating type of P. capsici. Primers Pcap-1 and Pcap-2 were designed from this DNA fragment to specifically detect the A1 mating type. Polymerase chain reaction (PCR) using these primers amplified an expected 997-bp fragment from known A1 mating types, but yielded a 508-bp fragment from known A2 mating types. This PCR-based assay could be adapted to accurately and rapidly detect the co-occurrence of A1 and A2 P. capsici mating types from field material.

Distribution of mating types and genetic diversity induced by sexual recombination in Setosphaeria turcica in northern China

2007 ◽  
Vol 1 (4) ◽  
pp. 368-376 ◽  
Author(s):  
Yongshan Fan ◽  
Jifang Ma ◽  
Xiumei Gui ◽  
Xinlong An ◽  
Shuqin Sun ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Northern China ◽  
Mating Types ◽  
Setosphaeria Turcica ◽  
Sexual Recombination

The Research on Computation of Researchers Certainty Factor of Bridge's Durability Evaluation Based on the Indeterminate AHP

2014 ◽  
Vol 578-579 ◽  
pp. 1469-1472
Author(s):  
Xiao Zhen Chen ◽  
Xue Jun Zhang
Keyword(s):  
Lower Bound ◽  
Similarity Theory ◽  
Research Result ◽  
Weight Coefficient ◽  
Practical Experience ◽  
Relative Importance ◽  
Certainty Factor ◽  
Average Value ◽  
Judgment Matrix ◽  
Very High

Because of fuzziness, uncertainty of structure and researchers practical experience, it is more practical to express the relative importance of indexes with interval number. Firstly, according to researchers indeterminate judgment matrix, the upper and lower bound matrixes are formed; secondly, the similarity and the differences of the upper and lower bound matrixes of the relative importance matrix from different experts is studied by using the similarity theory of vector; lastly, certainty factor of researchers according to the upper and lower bound matrixes can be calculated, and the average value is regarded as the researchers certainty factor. The certainty factors of researchers upper and lower bound matrixes are consider together, the researchers experience is fully considered and the error from indeterminate judgment matrix to indeterminate judgment matrix is avoided. The result affords basis to calculate the weight coefficient, the research result comparing with the other method showed that the computation accuracy in this paper was very high.

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