The Supernumerary Chromosome of Nectria haematococca That Carries Pea-Pathogenicity-Related Genes Also Carries a Trait for Pea Rhizosphere Competitiveness

ABSTRACT Fungi are found in a wide range of environments, and the ecological and host diversity of the fungus Nectria haematococca has been shown to be due in part to unique genes on different supernumerary chromosomes. These chromosomes have been called “conditionally dispensable” (CD) since they are not needed for axenic growth but are important for expanding the host range of individual isolates. From a biological perspective, the CD chromosomes can be compared to bacterial plasmids that carry unique genes that can define the habits of these microorganisms. The current study establishes that the N. haematococca PDA1-CD chromosome, which contains the genes for pea pathogenicity (PEP cluster) on pea roots, also carries a gene(s) for the utilization of homoserine, a compound found in large amounts in pea root exudates. Competition studies demonstrate that an isolate that lacks the PEP cluster but carries a portion of the CD chromosome which includes the homoserine utilization (HUT) gene(s) is more competitive in the pea rhizosphere than an isolate without the CD chromosome.

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SEX AND SUPERNUMERARY CHROMOSOMES IN THE DIOECIOUS GRASS SOHNSIA FILIFOLIA

Canadian Journal of Genetics and Cytology ◽

10.1139/g72-020 ◽

1972 ◽

Vol 14 (1) ◽

pp. 175-180 ◽

Cited By ~ 1

Author(s):

D. N. Singh

Keyword(s):

Sex Determination ◽

Y Chromosome ◽

Supernumerary Chromosome ◽

The Other ◽

Male Plant ◽

Diploid Male ◽

Male And Female ◽

Supernumerary Chromosomes ◽

Determination System ◽

Sex Determination System

A dioecious grass Sohnsia filifolia (Fourn.) Airy Shaw (Syn. Calamochloa filifolia Fourn.) from Mexico has been found to have 2n = 20 chromosomes in both male and female plants. The staminate plants have one chromosome much longer than the other chromosomes of the complement. One pistillate plant was found to have 30 chromosomes, among which the largest chromosome is quite similar to the largest component of the diploid male plant. The longest chromosome has been designated as the Y chromosome. An XY-mechanism of the Drosophilia type has been suggested for the sex determination system in this species. One small supernumerary chromosome was observed in the microsporocytes of some male plants, but was absent in roots.

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Reverse transcriptase-related enzymes are associated with horizontal chromosome transfer in an asexual pathogen

10.7287/peerj.preprints.1324v1 ◽

2015 ◽

Author(s):

Xiaoqiu Huang ◽

Anindya Das ◽

Binod B Sahu ◽

Subodh K Srivastava ◽

Leonor F Leandro ◽

...

Keyword(s):

Reverse Transcriptase ◽

Root Rot ◽

Supernumerary Chromosome ◽

Open Reading Frames ◽

Nucleotide Polymorphisms ◽

Single Nucleotide ◽

Chromosome Transfer ◽

Supernumerary Chromosomes ◽

The Mean ◽

Reading Frames

Supernumerary chromosomes have been shown to transfer horizontally from one isolate to another. However, the mechanism by which horizontal chromosome transfer (HCT) occurs is unknown. In this study, we compared the genomes of 11 isolates comprising six Fusarium species that cause soybean sudden death syndrome (SDS) or bean root rot (BRR), and detected numerous instances of HCT in supernumerary chromosomes. We also identified a statistically significant number (21 standard deviations above the mean) of single nucleotide polymorphisms (SNPs) in the supernumerary chromosomes between isolates of the asexual pathogen F. virguliforme. Supernumerary chromosomes carried reverse transcriptase-related genes (RVT); the presence of long RVT open reading frames (ORFs) in the supernumerary chromosome was correlated with the presence of two or more chromosome copies with a significant number of SNPs between them. Our results suggest that supernumerary chromosomes transfer horizontally via an RNA intermediate. Understanding the mechanism by which HCT occurs will have a profound impact on understanding evolution and applying biotechnology as well as accepting HCT as a natural source of genetic variation.

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Duplication of a Conditionally Dispensable Chromosome Carrying Pea Pathogenicity (PEP) Gene Clusters in Nectria haematococca

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-20-12-1495 ◽

2007 ◽

Vol 20 (12) ◽

pp. 1495-1504 ◽

Cited By ~ 6

Author(s):

Hamid S. Garmaroodi ◽

Masatoki Taga

Keyword(s):

Pathogenic Fungi ◽

Gene Clusters ◽

Chromosome Counting ◽

Nectria Haematococca ◽

Supernumerary Chromosomes ◽

Dosage Effects ◽

Dispensable Chromosome ◽

Multiple Copies ◽

Fusion Products

A supernumerary chromosome called a conditionally dispensable chromosome (CDC) is essential for pathogenicity of Nectria haematococca on pea. Among several CDCs discovered in N. haematococca, the PDA1 CDC that harbors the pisatin demethylation gene PDA1 is one of the best-studied CDCs and serves as a model for plant-pathogenic fungi. Although the presence of multiple copies is usual for supernumerary chromosomes in other eukaryotes, this possibility has not been examined well for any CDCs in N. haematococca. In this study, we produced strains with multiple copies of the PDA1 CDC by protoplast fusion and analyzed dosage effects of this chromosome. Using multiple methods, including cytological chromosome counting and fluorescence in situ hybridization, the fusion products between two transformants derived from the same strain that bears a single PDA1 CDC were shown to contain two PDA1 CDCs from both transformants and estimated to be haploid resulting from the deletion of an extra set or sets of A chromosomes in the fused nuclei. In phenotype assays, dosage effects of PDA1 CDC in the fusion products were evident as increased virulence and homoserine-utilizing ability compared with the parents. In a separate fusion experiment, PDA1 CDC accumulated up to four copies in a haploid genome.

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Distribution and host diversity of Amoebophryidae parasites across oligotrophic waters of the Mediterranean Sea

Biogeosciences ◽

10.5194/bg-8-267-2011 ◽

2011 ◽

Vol 8 (2) ◽

pp. 267-278 ◽

Cited By ~ 36

Author(s):

R. Siano ◽

C. Alves-de-Souza ◽

E. Foulon ◽

El M. Bendif ◽

N. Simon ◽

...

Keyword(s):

Mediterranean Sea ◽

Marine Ecosystems ◽

Natural Environments ◽

Coastal Station ◽

Host Diversity ◽

Eukaryotic Community ◽

Wide Range ◽

The Mediterranean ◽

Host Infection

Abstract. Sequences affiliated to Syndiniales (Marine alveolate, MALV) regularly dominate 18S rDNA genetic libraries of nearly all marine ecosystems investigated so far. Among them, Amoebophryidae (MALV group II) is composed of numerous and genetically distant environmental sequences, where Amoebophrya is the only known and formally described genus. Amoebophrya species include virulent pathogens for a wide range of dinoflagellate species. Beside their regular occurrence in marine ecosystems, their quantitative distribution and the environmental factors triggering host infection have barely been studied in open oligotrophic waters. In order to understand the functional role of these parasites in natural environments, we studied the distribution and contribution to the eukaryotic community of the small free-living stage of Amoebophryidae (the dinospores) along a transect in the Mediterranean Sea, as well as their host diversity at three oligotrophic stations. Dinospores were more abundant at a coastal station (max. 1.5 × 103 cells ml−1) than in oligotrophic waters (max. 51 ± 16.3 cells ml−1), where they represented 10.3 to 34.9% of the total eukaryotic community at 40 and 30 m depth, respectively and 21.2% on average along the water column. Positive correlation was found between dinospore occurrence and higher concentration of NO3 + NO2 at the coastal station. At selected stations, out of 38 different dinoflagellates taxa identified, 15 were infected, among which a majority were not recognized as Amoebophryidae host so far. Prevalences (percentage of infected cells) generally varied between 1% and 10%, with a notable exception for Blepharocysta paulsenii for which 25% of cells were infected at the most oligotrophic station. The present study shows that dinospores are able to thrive and infect dinoflagellates both in coastal and ultra-oligotrophic open waters. Our results emphasize the role of parasitism in microbial food web dynamics and ultimately on biogeochemical cycles.

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Moving research on resilience into the 21st century: Theoretical and methodological considerations in examining the biological contributors to resilience

Development and Psychopathology ◽

10.1017/s0954579403000373 ◽

2003 ◽

Vol 15 (3) ◽

pp. 773-810 ◽

Cited By ~ 196

Author(s):

W. JOHN CURTIS ◽

DANTE CICCHETTI

Keyword(s):

Neural Plasticity ◽

Theoretical Perspective ◽

Theoretical Framework ◽

Explanatory Models ◽

Conceptual Foundation ◽

Biological Perspective ◽

Wide Range ◽

Competent Functioning ◽

Methodological Considerations ◽

Theoretical Considerations

Empirical investigations of resilience over the past 30 years have examined a wide range of psychosocial correlates of, and contributors to, this phenomenon. Thus far, theoretical treatments of resilience have focused almost exclusively on psychosocial levels of analysis to derive explanatory models. However, there have been no formal discussions of either theory or research that have examined the biological contributors to, or correlates of, competent functioning despite the experience of adversity. This paper seeks to fill this gap and sets forth a preliminary theoretical framework and outline of empirical strategies for studying the biological underpinnings of resilience. The initial sections of the paper discuss the particular suitability of a transactional organizational theoretical perspective as a conceptual foundation for including a biological level of analysis within the extant theoretical framework of resilience. Subsequently, other important theoretical considerations for the inclusion of a biological perspective on resilience are discussed, including the avoidance of an approach that would reduce resilience to merely a biological process, the application of the constructs of multifinality and equifinality to a biological perspective on resilience, as well as a general discussion of the potential for utilization of brain imaging and other technologies in the study of resilience. The possible relation between the mechanisms of neural plasticity and resilience are examined in some detail, with specific suggestions concerning research questions needed to examine this association. Sections of the paper discuss the likely relation of several areas of brain and biological functioning with resilience, including emotion, cognition, neuroendocrine and immune functioning, and genetics. The paper concludes with a discussion of the implications of a biological perspective on resilience for preventive interventions.

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The Genome of Nectria haematococca: Contribution of Supernumerary Chromosomes to Gene Expansion

PLoS Genetics ◽

10.1371/journal.pgen.1000618 ◽

2009 ◽

Vol 5 (8) ◽

pp. e1000618 ◽

Cited By ~ 283

Author(s):

Jeffrey J. Coleman ◽

Steve D. Rounsley ◽

Marianela Rodriguez-Carres ◽

Alan Kuo ◽

Catherine C. Wasmann ◽

...

Keyword(s):

Nectria Haematococca ◽

Supernumerary Chromosomes ◽

Gene Expansion

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Reverse transcriptase-related enzymes are associated with horizontal chromosome transfer in an asexual pathogen

10.7287/peerj.preprints.1324 ◽

2015 ◽

Author(s):

Xiaoqiu Huang ◽

Anindya Das ◽

Binod B Sahu ◽

Subodh K Srivastava ◽

Leonor F Leandro ◽

...

Keyword(s):

Reverse Transcriptase ◽

Root Rot ◽

Supernumerary Chromosome ◽

Open Reading Frames ◽

Nucleotide Polymorphisms ◽

Single Nucleotide ◽

Chromosome Transfer ◽

Supernumerary Chromosomes ◽

The Mean ◽

Reading Frames

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ANALYSIS OF FACTORS GOVERNING IN VITRO ACCUMULATION OF ZOOSPORES OF PYTHIUM APHANIDERMATUM ON ROOTS: I. BEHAVIOR OF ZOOSPORES

Canadian Journal of Microbiology ◽

10.1139/m64-022 ◽

1964 ◽

Vol 10 (2) ◽

pp. 151-162 ◽

Cited By ~ 48

Author(s):

D. J. Royle ◽

C. J. Hickman

Keyword(s):

Root Exudate ◽

Pythium Aphanidermatum ◽

Root Tips ◽

Water Suspension ◽

Large Numbers ◽

Wide Range ◽

Early Germination ◽

Pea Roots ◽

Germ Tubes

Zoospores of Pythium aphanidermatum in distilled water suspension responded to intact pea roots by massing in large numbers at the sites of elongation behind the root tips. They showed preferential attraction to wounds made by puncturing the epidermis, and to the stele exposed at the cut ends of roots. Massing of zoospores was followed, almost immediately, by encystment and early germination, the germ tubes being directed towards the source of stimulation. The phenomenon was non-specific over a wide range of plants examined. Root exudate and extract, diffusing from the ends of capillary tubes containing these materials in agar, caused identical zoospore responses. Analysis of zoospore movement under stimulation revealed a sequence of responses—initial disruption of the typical course of movement, attraction, trapping, and early cessation of movement by encystment. Attraction was equated with chemotaxis, whilst trapping showed features of kineses.

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Centromere Fissions, Complementary Isochromosomes, Telomeric Fusions, Balancing Supernumerary Chromosomes, Neocentromeres, Jumping Translocations, and Chromothripsis

10.1093/med/9780199329007.003.0012 ◽

2018 ◽

Author(s):

R. J McKinlay Gardner ◽

David J Amor

Keyword(s):

Chromosomal Rearrangements ◽

Marker Chromosome ◽

Chromosome Count ◽

Supernumerary Chromosome ◽

Submetacentric Chromosome ◽

Supernumerary Chromosomes ◽

Complex Rearrangement ◽

Small Supernumerary Marker Chromosome

This chapter reviews a number of very rare chromosomal rearrangements: centromere fissions, complementary isochromosomes, telomeric fusions, balancing supernumerary chromosomes, neocentromeres, jumping translocations, and chromothripsis. Centromere fission results when a metacentric or submetacentric chromosome splits at the centromere, giving rise to two stable telocentric products. The Robertsonian fission reverses the fusion that had originally generated it. Telomeric fusion leads to a 45-chromosome count. With the balanced complementary isochromosome carrier, two stable exactly metacentric products are generated. A balancing small supernumerary marker chromosome contains material deleted from the normal homolog. A supernumerary chromosome lacking a normal centromere can become stable and functional due to the generation of a neocentromere. In jumping translocations, a segment can move from one chromosome to two or more recipient chromosomes. Chromothripsis takes complex rearrangement to a yet more complex level. The reproductive risks associated with each are noted.

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New cases of supernumerary chromosomes in characiform fishes

Genetics and Molecular Biology ◽

10.1590/s1415-47571999000300010 ◽

1999 ◽

Vol 22 (3) ◽

pp. 345-349 ◽

Cited By ~ 34

Author(s):

Paulo Cesar Venere ◽

Carlos Suetoshi Miyazawa ◽

Pedro Manoel Galetti Junior

Keyword(s):

Supernumerary Chromosome ◽

Chromomycin A3 ◽

Widespread Occurrence ◽

Supernumerary Chromosomes

Supernumerary chromosomes were described for five species of Neotropical characiform fishes. These extra chromosomes were small, acrocentric and fully heterochromatic in Leporinus friderici from two different localities as well as in Leporinus sp., but metacentric and fully heterochromatic in Cyphocharax modesta and Prochilodus nigricans. In Characidium cf. zebra, this element was small, acrocentric and euchromatic. GC-rich DNA blocks were observed in the supernumerary chromosome of Leporinus sp. using chromomycin A3. The widespread occurrence of these extra chromosomal elements suggests their independent origins.

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