Pathogen diversity and mating types of Didymella rabiei isolates collected from Morocco

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.

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Phony peach disease: past and present impact on the peach industry in the southeastern U.S.A

CABI Agriculture and Bioscience ◽

10.1186/s43170-021-00049-4 ◽

2021 ◽

Vol 2 (1) ◽

Author(s):

Kendall A. Johnson ◽

Clive H. Bock ◽

Phillip M. Brannen

Keyword(s):

New Technologies ◽

Current Knowledge ◽

Future Research ◽

Management Options ◽

Disease Epidemiology ◽

Pathogen Diversity ◽

Foundational Research ◽

Global Threat ◽

And Control ◽

The Impact

Abstract Background Phony peach disease (PPD) is caused by the plant pathogenic bacterium Xylella fastidiosa subsp. multiplex (Xfm). Historically, the disease has caused severe yield loss in Georgia and elsewhere in the southeastern United States, with millions of PPD trees being removed from peach orchards over the last century. The disease remains a production constraint, and management options are few. Limited research has been conducted on PPD since the 1980s, but the advent of new technologies offers the opportunity for new, foundational research to form a basis for informed management of PPD in the U.S. Furthermore, considering the global threat of Xylella to many plant species, preventing import of Xfm to other regions, particularly where peach is grown, should be considered an important phytosanitary endeavor. Main topics We review PPD, its history and impact on peach production, and the eradication efforts that were conducted for 42 years. Additionally, we review the current knowledge of the pathogen, Xfm, and how that knowledge relates to our understanding of the peach—Xylella pathosystem, including the epidemiology of the disease and consideration of the vectors. Methods used to detect the pathogen in peach are discussed, and ramifications of detection in relation to management and control of PPD are considered. Control options for PPD are limited. Our current knowledge of the pathogen diversity and disease epidemiology are described, and based on this, some potential areas for future research are also considered. Conclusion There is a lack of recent foundational research on PPD and the associated strain of Xfm. More research is needed to reduce the impact of this pathogen on peach production in the southeastern U.S., and, should it spread internationally, wherever peaches are grown.

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

Genetics ◽

10.1093/genetics/144.4.1437 ◽

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.

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New Mating Types in Physarum polycephalum

Mycologia ◽

10.2307/3758667 ◽

1977 ◽

Vol 69 (2) ◽

pp. 421 ◽

Cited By ~ 9

Author(s):

O'Neil Ray Collins ◽

Hsi-Chang Tang

Keyword(s):

Physarum Polycephalum ◽

Mating Types

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

Journal of the American Society for Horticultural Science ◽

10.21273/jashs04013-17 ◽

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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