Control of sexuality in Phytophthora cinnamomi

1974 ◽  
Vol 22 (4) ◽  
pp. 669 ◽  
Author(s):  
ST Chang ◽  
CJ Shepherd ◽  
BH Pratt
Keyword(s):  
Mating Type ◽  
Phytophthora Cinnamomi ◽  
Chemical Stimulation ◽  
Mating Types ◽  
Hyphal Fusion ◽  
Field Isolates ◽  
Heterokaryon Formation ◽  
Oospore Formation

The mating type behaviour of 176 single zoospore isolates collected from 11 dissected sporangia of Phytophthora cinnamomi Rands was examined and the results confirmed previous conclusions from studies of field isolates, that two compatibility types may be involved in the formation of oospores in this fungus. The bilateral formation of sexual spores in paired cultures is believed to occur via the hyphal fusion of two compatibility types and it is thought that chemical stimulation is not involved. Oospore production is also affected by nutrition and innate characters of the isolates used. Determination of the mating reactions of terminal hyphae isolated from mixed A1 and A2 cultures suggested that extensive heterokaryosis of A1 and A2 type nuclei did not occur in the vegetative hyphae of either mating type, and that heterokaryon formation was probably restricted to the site of oospore formation. The absence of 'vegetative' heterokaryosis between the two mating types of P. cinnamomi is postulated and the control of sexuality in this fungus is discussed.

Pathogenicity of Phytophthora cinnamomi Towards Nothofagus cunninghamii

1975 ◽  
Vol 23 (2) ◽  
pp. 277 ◽  
Author(s):  
G Weste
Keyword(s):  
Mating Type ◽  
Root Rot ◽  
Host Plants ◽  
Phytophthora Cinnamomi ◽  
Dry Weight ◽  
Mating Types

Two-year-old plants of Nothofagus cunninghamii were inoculated with isolates of either A1 or A2 mating types of Phytophthora cinnamomi. Both mating types were pathogenic, causing root rot and cankers, and resulting in significant reductions of height and dry weight compared with controls. Death occurred in all host plants inoculated with the A1 mating type, but in only 60% of those inocu- lated with the A2 isolate. Symptoms were correspondingly more severe in plants inoculated with the A1 mating type of the pathogen than in those inoculated with the A2 type.

Somatic Segregation by Microconidial Isolation in Synthesised Heterokaryons of Neurospora crassa

1946 ◽  
Vol 62 (3) ◽  
pp. 299-303
Author(s):  
E. R. Sansome ◽  
F. W. Sansome
Keyword(s):  
Neurospora Crassa ◽  
Botrytis Cinerea ◽  
Mating Type ◽  
Mating Types ◽  
Sex Factors ◽  
Single Spore ◽  
Hyphal Fusion ◽  
Male Gametes ◽  
Widespread Phenomenon ◽  
And Bisexual

Heterokaryosis is the condition in which one cell of a mycelium contains two or more genetically different nuclei. Hansen and Smith (1932), working with Botrytis cinerea, which has multi-nucleate spores, showed that single-spore cultures of this fungus sometimes contained two types of nuclei and that such heterokaryotic types could readily be induced by hyphal fusion between different homokaryotic types. These authors analysed individuals from thirty genera of imperfect fungi and found more than half of them to be heterokaryotic. It seems, therefore, that heterokaryosis is a widespread phenomenon among such fungi.N. crassa is a heterothallic fungus with an eight-spored ascus and a pair of well-defined mating-type factors which have been very generally called sex factors. Perithecia are formed only when cultures of the opposite mating types are brought into contact. Both mating types can produce ascogonia, generally conceived to be female organs, and microconidia, sometimes called spermatia (Dodge, 1935), which may correspond to male gametes. Therefore it is doubtful whether the mating-type factors are true sex factors.A non-committal term such as “mating type” or “incompatibility factor” is preferable. However, because of the convenience of the terms associated with sex, such as “unisexual” and “bisexual”, I shall follow previous authors (Dodge, Lindegren, Beadle) in using these terms with reference to the mating-type factors, at the same time emphasising that these factors may not be sex factors in the generally accepted sense of the term.

scholarly journals Distribution of Mating Type and Sexual Status in Chinese Rice Blast Populations

Plant Disease ◽  
2009 ◽  
Vol 93 (3) ◽  
pp. 238-242 ◽  
Author(s):  
Jing Zeng ◽  
Shujie Feng ◽  
Jiangqiao Cai ◽  
Ling Wang ◽  
Fei Lin ◽  
...  
Keyword(s):  
Mating Type ◽  
Magnaporthe Oryzae ◽  
Rice Blast ◽  
Rice Blast Fungus ◽  
The Other ◽  
Fertility Level ◽  
Mating Types ◽  
Field Isolates ◽  
Sexual Status ◽  
Blast Fungus

A collection of 520 field isolates of the rice blast fungus (Magnaporthe oryzae) originating from five provinces in China was assessed for mating type and sexual fertility. One of the two tester sets was composed of isolates collected from barley and the other from rice. Two mating types (MAT1-1 and MAT1-2) were identified among the 443 fertile isolates. The two mating types were roughly in balance with one another in the southwestern region but one or the other predominated in the southeastern and southern regions. Male-only fertile isolates were the most common, and only a few hermaphroditic and no female only fertile isolates were detected. The fertility level of the isolates was variable. Isolates from Jiangsu were more fertile than those from Fujian. The mating capacity of the testers collected from barley was higher than that of those collected from rice, but this was because the MAT1-2 testers differed very significantly from one another. In contrast, the mating capacities of the two MAT1-1 testers were similar to one another.

scholarly journals Hyphal fusions in the wood-rotting fungusSchizophyllum commune: I. The effects of incompatibility factors

1970 ◽  
Vol 15 (1) ◽  
pp. 19-28 ◽  
Author(s):  
Sayed S. Ahmad ◽  
Philip G. Miles
Keyword(s):  
Cell Wall ◽  
Mating Type ◽  
Schizophyllum Commune ◽  
Mating Types ◽  
Hyphal Fusion ◽  
Fusion Frequency ◽  
Degrading Enzyme ◽  
Cell Wall Degrading Enzyme ◽  
Incompatibility Factor ◽  
A Cell

SUMMARYEffects of the incompatibility factors inSchizophyllum communeFries on the process of hyphal fusion are described. A role for the A incompatibility factor in hyphal fusion is indicated. Matings between strains with different mating types have higher fusion frequencies than matings between strains with the same mating types. Evidence is presented that the differences in fusion frequencies are not due to genetical factors other than mating types. When two strains of different mating types are grown in the same culture plate, but separated by a cellophane membrane, the strains are altered in some unexplained manner in such a way that even matings between strains of the same mating type have a higher fusion frequency than occurs in matings between compatible strains not so treated. Matings leading to the formation of common-B and dikaryotic mycelia have comparable fusion frequencies while those leading to the formation of common-A mycelia have a far lower frequency of fusions. It has been demonstrated that high fusion frequency is associated with heterozygosity at the A locus. It is suggested that a repression–derepression mechanism involving a cell wall degrading enzyme or enzymes may be involved in the regulation of hyphal fusion.

scholarly journals Mating types of Phytophthora colocasiae on the island of Upolu, Samoa

2018 ◽  
Vol 71 ◽  
pp. 289-292 ◽  
Author(s):  
Kieran D. Mellow ◽  
Joy L. Tyson ◽  
Robert A. Fullerton ◽  
Angelika Tugaga ◽  
Fa'alelei Tunupopo ◽  
...  
Keyword(s):  
Sexual Reproduction ◽  
Mating Type ◽  
Genetic Recombination ◽  
Leaf Blight ◽  
Phytophthora Nicotianae ◽  
Mating Types ◽  
Comprehensive Understanding ◽  
Phytophthora Colocasiae ◽  
Oospore Formation ◽  
Taro Leaf Blight

Taro leaf blight (TLB) caused by Phytophthora colocasiae is a damaging disease that destroyed Samoa’s taro industry following its introduction in 1993. The aim of this study was to determine the occurrence of the A1 and A2 mating types of P. colocasiae for a more comprehensive understanding of the risk the pathogen poses for the future of the taro industry in Samoa. In September 2015, 54 isolates of P. colocasiae were collected from taro leaf blight lesions from 13 farms around the island of Upolu, Samoa. The mating types of each isolate was determined by observation of oospore formation when paired with tester isolates of Phytophthora nicotianae of known mating types (A1 or A2). Fifty isolates were found to be A2 mating type and four did not form oospores with either mating type. No A1 or self-fertile isolates were found. These results suggest that the A1 mating type has not been introduced to the island of Upolu, preventing the formation of oospores between compatible mating types of P. colocasiae and lessening the risk of new and potentially more threatening genotypes of the pathogen from emerging through genetic recombination. Keywords taro leaf blight, Colocasia esculenta, taro, sexual reproduction

scholarly journals Drivers of Mating Type Composition in Tetrahymena thermophila

2020 ◽  
Vol 12 (12) ◽  
pp. 2328-2343
Author(s):  
Guangying Wang ◽  
Kai Chen ◽  
Jing Zhang ◽  
Shanjun Deng ◽  
Jie Xiong ◽  
...  
Keyword(s):  
Natural Selection ◽  
Mating Type ◽  
Tetrahymena Thermophila ◽  
Evolutionary Strategies ◽  
Whole Genome ◽  
Mating Types ◽  
Type Composition ◽  
Theoretical Predictions ◽  
Single Mating

Abstract Sex offers advantages even in primarily asexual species. Some ciliates appear to utilize such reproductive strategy with many mating types. However, the factors determining the composition of mating types in the unicellular ciliate Tetrahymena thermophila are poorly understood, and this is further complicated by non-Mendelian determination of mating type in the offspring. We therefore developed a novel population genetics model to predict how various factors influence the dynamics of mating type composition, including natural selection. The model predicted either the coexistence of all seven mating types or fixation of a single mating type in a population, depending on parameter combinations, irrespective of natural selection. To understand what factor(s) may be more influential and to test the validity of theoretical prediction, five replicate populations were maintained in laboratory such that several factors could be controlled or measured. Whole-genome sequencing was used to identify newly arising mutations and determine mating type composition. Strikingly, all populations were found to be driven by strong selection on newly arising beneficial mutations to fixation of their carrying mating types, and the trajectories of speed to fixation agreed well with our theoretical predictions. This study illustrates the evolutionary strategies that T. thermophila can utilize to optimize population fitness.

scholarly journals First Report of A1 and A2 Mating Types of Phytophthora infestans on Potato and Tomato in Nepal

Plant Disease ◽  
1998 ◽  
Vol 82 (9) ◽  
pp. 1064-1064 ◽  
Author(s):  
S. K. Shrestha ◽  
K. Shrestha ◽  
K. Kobayashi ◽  
N. Kondo ◽  
R. Nishimura ◽  
...  
Keyword(s):  
Late Blight ◽  
Phytophthora Infestans ◽  
Mating Type ◽  
Simultaneous Occurrence ◽  
Mating Types ◽  
Isozyme Loci ◽  
Oospore Formation ◽  
The Hill ◽  
Pathogenic Diversity ◽  
Important Disease

Late blight caused by Phytophthora infestans (Mont.) de Bary is an important disease of potato and tomato that occurs annually in the hills and occasionally in the terai (plain) of Nepal. In 1996 and 1997, each year, 50 samples of late blight-infected potato and tomato leaves were collected from the hill and terai areas. The pathogen was cultured on Rye A agar. Each isolate was paired on clear V8 agar with reference isolates DN111 (A1 mating type) and DN107 (A2 mating type) received from Hokkaido University, Japan, and examined for oospore formation after 10 to 15 days of incubation at 20°C. The proportion of A2 isolates was 6% in 1996 and 42% in 1997. The A2 isolates were mainly from the high hills (2,000 to 2,500 m) where local and Andean types of potatoes are grown. Analysis of genotypes of isolates at the glucosephosphate isomerase (GPI-1), malic enzyme (ME), and peptidase (PEP-1) (1,2) isozyme loci revealed genetic diversity between A1 and A2 isolates. A1 isolates from potato were either homozygous (100/100) or heterozygous (86/100) for GPI-1, whereas all A1 isolates from tomato were heterozygous (86/100). All A1 isolates were homozygous (100/100) at the ME locus and heterozygous (92/100) at the PEP-1 locus. A2 isolates were homozygous (100/100) at all isozyme loci. The results show that both A1 and A2 mating types of P. infestans are present in Nepal, and that they display different isozyme genotypes. It is speculated that the A1 type may have migrated with potatoes from Europe while the A2 type may have been introduced with Andean potatoes from Latin America more recently. The simultaneous occurrence of both mating types may allow the fungus to increase its pathogenic diversity and to survive by means of oospores. References: (1) A. A. Mosa et al. Plant Pathol. 42:26, 1993. (2) P. W. Tooley et al. J. Hered. 76:431, 1985.

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.

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