scholarly journals Ecological Constraints Limit the Fitness of Fungal Hybrids in the Heterobasidion annosum Species Complex

2007 ◽  
Vol 73 (19) ◽  
pp. 6106-6111 ◽  
Author(s):  
Matteo Garbelotto ◽  
Paolo Gonthier ◽  
Giovanni Nicolotti
Keyword(s):  
Experimental Evidence ◽  
Species Complex ◽  
Fungal Species ◽  
Host Specialization ◽  
Heterobasidion Annosum ◽  
Postzygotic Isolation ◽  
Ecological Constraints ◽  
Closely Related Species ◽  
Parasitic Fungi ◽  
Isolation Mechanisms

ABSTRACT The ability of two closely related species to maintain species boundaries in spite of retained interfertility between them is a documented driving force of speciation. Experimental evidence to support possible interspecific postzygotic isolation mechanisms for organisms belonging to the kingdom Fungi is still missing. Here we report on the outcome of a series of controlled comparative inoculation experiments of parental wild genotypes and F1 hybrid genotypes between closely related and interfertile taxa within the Heterobasidion annosum fungal species complex. Results indicated that these fungal hybrids are not genetically unfit but can fare as well as parental genotypes when inoculated on substrates favorable to both parents. However, when placed in substrates favoring one of the parents, hybrids are less competitive than the parental genotypes specialized on that substrate. Furthermore, in some but not all fungus × plant combinations, a clear asymmetry in fitness was observed between hybrids carrying identical nuclear genomes but different cytoplasms. This work provides some of the first experimental evidence of ecologically driven postzygotic reinforcement of isolation between closely related fungal species characterized by marked host specificity. Host specialization is one of the most striking traits of a large number of symbiotic and parasitic fungi; thus, we suggest the ecological mechanism proven here to reinforce isolation among Heterobasidion spp. may be generally valid for host-specialized fungi. The validity of this generalization is supported by the low number of known fungal hybrids and by their distinctive feature of being found in substrates different from those colonized by parental species.

Planting Betula pendula on pine sites infested by Heterobasidion annosum: disease transfer, silvicultural evaluation, and community of wood-inhabiting fungi

2004 ◽  
Vol 34 (1) ◽  
pp. 120-130 ◽  
Author(s):  
Vaidotas Lygis ◽  
Rimvydas Vasiliauskas ◽  
Jan Stenlid
Keyword(s):  
Root Rot ◽  
Forest Regeneration ◽  
Betula Pendula ◽  
Root Systems ◽  
Fungal Species ◽  
Heterobasidion Annosum ◽  
Strong Impact ◽  
Fungal Isolation ◽  
Somatic Incompatibility ◽  
Forest Sites

Persistence of the root rot pathogen Heterobasidion annosum (Fr.) Bref. s.s. on infested areas and its transfer to a forest regeneration was studied in three forest sites in eastern Lithuania. The sites represented H. annosum disease centres in Pinus sylvestris L. stands, which were clear-felled and replanted with Betula pendula Roth 25 years prior to our study. Fungal isolation from trees and stumps on each site was performed on both replanted B. pendula and surrounding P. sylvestris from the previous generation. Low productivity of B. pendula stands (45.0–76.1 m3·ha–1), high mortality rates, and comparatively low vigor of trees (measured as crown densities) indicated a strong impact of root rot. Based on somatic incompatibility tests, we detected large spreading areas of clones of H. annosum (up to 48 m across) and old (35- to 40-year-old) clonal individuals. Territorial clones covered areas that encompassed both previous stands of P. sylvestris and current stands of B. pendula. Our results showed that H. annosum is able to persist in root systems of diseased trees for decades and readily attack birch replanted on infested sites. In addition, a total of 83 fungal species (out of 398 isolates) was found as a result of sampling 508 B. pendula, 49 P. sylvestris, 21 Juniperus communis L., and 1 Salix cinerea L. trees.

A molecular phylogeny of the “Madascincus polleni species complex”, with description of a new species of scincid lizard from the coastal dune area of northern Madagascar

Zootaxa ◽  
2011 ◽  
Vol 2876 (1) ◽  
pp. 1 ◽  
Author(s):  
AURÉLIEN MIRALLES ◽  
JÖRN KÖHLER ◽  
FRANK GLAW ◽  
MIGUEL VENCES
Keyword(s):  
Dna Sequences ◽  
Species Complex ◽  
Nuclear Dna ◽  
Taxonomic Status ◽  
Nominal Species ◽  
Morphological Examination ◽  
Closely Related Species ◽  
A New Species ◽  
Evolutionary Lineages ◽  
Dune Area

The present paper constitutes a study on a taxonomically confusing group of closely related species belonging to the Malagasy skink genus Madascincus, currently encompassing the nominal species M. polleni, M. intermedius and M. stumpffi. Based on combined analyses of mitochondrial and nuclear DNA sequences (ND1 and RAG2 genes, respectively), and morphological examination, we provide evidence for the existence of at least four distinct evolutionary lineages within this complex: Madascincus stumpffi; Madascincus arenicola sp. nov. from northern Madagascar; and two cryptic species morphologically similar to the name-bearing types of M. polleni and M. intermedius. The two latter species, although genetically distinct, appear to be morphologically indistinguishable and their taxonomic status cannot be resolved until a better sampling will be available.

scholarly journals EVOLUTION OF REPRODUCTIVE ISOLATION WITHIN A PARASITIC FUNGAL SPECIES COMPLEX

Evolution ◽  
2007 ◽  
Vol 61 (7) ◽  
pp. 1781-1787 ◽  
Author(s):  
Mickael Le Gac ◽  
Michael E. Hood ◽  
Tatiana Giraud
Keyword(s):  
Reproductive Isolation ◽  
Species Complex ◽  
Fungal Species

scholarly journals Host Selection of Symbiotic Cyanobacteria in 31 Species of the Australian Cycad Genus: Macrozamia (Zamiaceae)

2010 ◽  
Vol 23 (6) ◽  
pp. 811-822 ◽  
Author(s):  
Michelle M. Gehringer ◽  
Jasper J. L. Pengelly ◽  
William S. Cuddy ◽  
Claus Fieker ◽  
Paul I. Forster ◽  
...  
Keyword(s):  
Microscopic Analysis ◽  
Fungal Species ◽  
Host Specialization ◽  
Rrna Gene ◽  
Natural Habitats ◽  
Diverse Range ◽  
Cyanobacterial Species ◽  
Wide Range ◽  
In The Wild ◽  
Selection Of

The nitrogen-fixing cyanobacterium Nostoc is a commonly occurring terrestrial and aquatic cyanobacterium often found in symbiosis with a wide range of plant, algal, and fungal species. We investigated the diversity of cyanobacterial species occurring within the coralloid roots of different Macrozamia cycad species at diverse locations throughout Australia. In all, 74 coralloid root samples were processed and 56 endosymbiotic cyanobacteria were cultured. DNA was isolated from unialgal cultures and a segment of the 16S rRNA gene was amplified and sequenced. Microscopic analysis was performed on representative isolates. Twenty-two cyanobacterial species were identified, comprising mostly Nostoc spp. and a Calothrix sp. No correlation was observed between a cycad species and its resident cyanobiont species. The predominant cyanobacterium isolated from 18 root samples occurred over a diverse range of environmental conditions and within 14 different Macrozamia spp. Phylogenetic analysis indicated that endosymbionts were not restricted to previously described terrestrial species. An isolate clustering with Nostoc PCC7120, an aquatic strain, was identified. This is the first comprehensive study to identify the endosymbionts within a cycad genus using samples obtained from their natural habitats. These results indicate that there is negligible host specialization of cyanobacterial endosymbionts within the cycad genus Macrozamia in the wild.

Systematics of the Adiantum philippense complex (Pteridaceae, Polypodiales) in Taiwan

Phytotaxa ◽  
2016 ◽  
Vol 263 (2) ◽  
pp. 113 ◽  
Author(s):  
LI-YAUNG KUO ◽  
TIAN-CHUAN HSU ◽  
YI-HAN CHANG ◽  
YAO-MOAN HUANG ◽  
WEN-LIANG CHIOU
Keyword(s):  
Cryptic Species ◽  
Related Species ◽  
Species Complex ◽  
The Other ◽  
Closely Related Species ◽  
Hybrid Combination ◽  
Reproductive Modes ◽  
Taxonomical Revision

Adiantum philippense s.l. is a member of once-pinnate Adiantum but comprise several cytotaxa with different ploidies and reproductive modes. According to the differences of cytotypes, the up-to-date revision had identified three subspecies under the A. philippense complex. In Taiwan, different ploidies and reproductive modes had also been found in this species complex, and existence of (a) cryptic species among these cytotypes had been suggested. The current study focuses on taxonomical revision of Taiwanese A. philippense complex. We sampled not only different Taiwanese cytotypes/populations but also all subspecies under A. philippense and the closely related species of them. By re-examining their phylogeny, ploidies, and reproductive modes, we confirmed that the sexual diploids in Taiwan belong to Adiantum menglianense, and this species is phylogenetically separated from A. philippense. We further approved that A. menglianense can be morphologically distinguished from A. philippense by their frond features and spore numbers in sporangia. Another taxon of Taiwanese A. philippense complex is A. philippense subsp. philippense, which is an apomictic and triploidy subspecies. Additionally, we assigned lectotypes of A. menglianense, and revised the hybrid combination of A. × meishanianum. We also provided a key in order to identify two taxa under Taiwanese A. philippense complex and the other once-pinnate Adiantum species in Taiwan.

Effects of leaching on fungal growth and decay of western redcedar

2009 ◽  
Vol 55 (5) ◽  
pp. 578-586 ◽  
Author(s):  
Russell J. Chedgy ◽  
Young Woon Lim ◽  
Colette Breuil
Keyword(s):  
Fungal Growth ◽  
Fungal Species ◽  
Heterobasidion Annosum ◽  
Thuja Plicata ◽  
Western Redcedar ◽  
Coniophora Puteana ◽  
Soil Block ◽  
Block Test ◽  
Thuja Plicata Donn

We tested the effect of leaching on the concentration of western redcedar (WRC; Thuja plicata Donn ex D. Don) heartwood extractives that are known to exhibit antimicrobial activity and correlated this with fungal growth and decay. We assessed the extractive tolerance of the following fungal species: Acanthophysium lividocaeruleum , Coniophora puteana , Heterobasidion annosum , Pachnocybe ferruginea , Phellinus sulphurascens , and Phellinus weirii by measuring their growth rate (mm/day) on media with or without WRC leachate. These data were correlated with the ability of the fungal species to grow on and decay leached versus nonleached WRC. We used an ergosterol assay to estimate growth and a standard soil-block test to assess decay. We estimated that leaching reduced the concentration of 5 major extractives: (–)-plicatic acid, β-thujaplicin, γ-thujaplicin, β-thujaplicinol, and thujic acid by ~80%. Phellinus sulphurascens exhibited the lowest extractive-tolerance in vitro, grew poorly on and caused minimal decay in nonleached WRC, but it grew well on and decayed pine and leached WRC. Coniophora puteana, H. annosum, and P. weirii displayed moderate to high tolerance to leachate, grew on and caused decay in nonleached as well as leached WRC, but their growth and decay were always greatest on leached WRC and pine, suggesting that leaching enhances decay by these fungi. Acanthophysium lividocaeruleum and Pachnocybe ferruginea exhibited high extractive-tolerance. Whereas A. lividocaeruleum clearly caused decay on all types of wood, no decay was observed with Pachnocybe ferruginea, which grew very slowly in the different wood species, and it may or may not be able to decay wood.

No biogeographical pattern for a root-associated fungal species complex

2010 ◽  
Vol 20 (1) ◽  
pp. 160-169 ◽  
Author(s):  
Valentin Queloz ◽  
Thomas N. Sieber ◽  
Ottmar Holdenrieder ◽  
Bruce A. McDonald ◽  
Christoph R. Grünig
Keyword(s):  
Species Complex ◽  
Fungal Species ◽  
Biogeographical Pattern

scholarly journals Genome Organization and Evolution of the AVR-Pita Avirulence Gene Family in the Magnaporthe grisea Species Complex

2008 ◽  
Vol 21 (5) ◽  
pp. 658-670 ◽  
Author(s):  
Chang Hyun Khang ◽  
Sook-Young Park ◽  
Yong-Hwan Lee ◽  
Barbara Valent ◽  
Seogchan Kang
Keyword(s):  
Gene Family ◽  
Repetitive Dna ◽  
Species Complex ◽  
Magnaporthe Grisea ◽  
Fungal Species ◽  
Avirulence Gene ◽  
Genomic Context ◽  
Dna Elements ◽  
Avr Gene ◽  
Repetitive Dna Elements

The avirulence (AVR) gene AVR-Pita in Magnaporthe oryzae prevents the fungus from infecting rice cultivars containing the resistance gene Pi-ta. A survey of isolates of the M. grisea species complex from diverse hosts showed that AVR-Pita is a member of a gene family, which led us to rename it to AVR-Pita1. Avirulence function, distribution, and genomic context of two other members, named AVR-Pita2 and AVR-Pita3, were characterized. AVR-Pita2, but not AVR-Pita3, was functional as an AVR gene corresponding to Pi-ta. The AVR-Pita1 and AVR-Pita2 genes were present in isolates of both M. oryzae and M. grisea, whereas the AVR-Pita3 gene was present only in isolates of M. oryzae. Orthologues of members of the AVR-Pita family could not be found in any fungal species sequenced to date, suggesting that the gene family may be unique to the M. grisea species complex. The genomic context of its members was analyzed in eight strains. The AVR-Pita1 and AVR-Pita2 genes in some isolates appeared to be located near telomeres and flanked by diverse repetitive DNA elements, suggesting that frequent deletion or amplification of these genes within the M. grisea species complex might have resulted from recombination mediated by repetitive DNA elements.

scholarly journals Conservation genomics of an Australian orchid complex with implications for the taxonomic and conservation status of Corybas dowlingii

2020 ◽  
Author(s):  
Natascha D. Wagner ◽  
Mark A. Clements ◽  
Lalita Simpson ◽  
Katharina Nargar
Keyword(s):  
Species Complex ◽  
Conservation Status ◽  
Taxonomic Status ◽  
Genomic Diversity ◽  
Hybrid Origin ◽  
Genetic Admixture ◽  
Conservation Genomics ◽  
Closely Related Species ◽  
Genomic Signatures ◽  
Genetic Position

AbstractThis study assessed genomic diversity in an Australian species complex in the helmet orchids to clarify taxonomic delimitation and conservation status of the threatened species Corybas dowlingii, a narrow endemic from southeast Australia. Taxonomic delimitation between the three closely related species C. aconitiflorus, C. barbarae, and C. dowlingii has been mainly based on floral traits which exhibit varying degrees of overlap, rendering species delimitation in the complex difficult. Genomic data for the species complex was generated using double-digest restriction-site associated DNA (ddRAD) sequencing. Maximum likelihood, NeighborNet, and Bayesian structure analyses showed genetic differentiation within the species complex and retrieved genomic signatures consistent with hybridisation and introgression between C. aconitiflorus and C. barbarae, and an intermediate genetic position of C. dowlingii indicating a hybrid origin of the species. The genetic structure analysis showed varying levels of genetic admixture for several C. aconitiflorus, C. barbarae, and C. dowlingii samples, thus further corroborating the presence of hybridisation and introgression within the species complex. The taxonomic status of C. dowlingii D.L.Jones was revised to C. × dowlingii D.L.Jones stat. nov. to reflect its hybrid origin. The conservation status of C. × dowlingii was assessed based on key ecological and ethical aspects, and recommendations made regarding its conservation status in Australian conservation legislation.

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