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Vegetative hyphal fusion and subsequent nuclear behavior in Epichloë grass endophytes.

Shoji JY, Charlton ND, Yi M, Young CA, Craven KD - PLoS ONE (2015)

Bottom Line: Epichloë species (including the former genus Neotyphodium) are fungal symbionts of many agronomically important forage grasses, and provide their grass hosts with protection from a wide range of biotic and abiotic stresses.Epichloë species include many interspecific hybrids with allodiploid-like genomes, which may provide the potential for combined traits or recombination to generate new traits.However, we also discuss additional factors, such as post-hybridization selection, that may be important to explain the recognized prevalence of hybrids in Epichloë species.

View Article: PubMed Central - PubMed

Affiliation: The Samuel Roberts Noble Foundation, Plant Biology Division, 2510 Sam Noble Parkway, Ardmore, Oklahoma 73401, United States of America.

ABSTRACT
Epichloë species (including the former genus Neotyphodium) are fungal symbionts of many agronomically important forage grasses, and provide their grass hosts with protection from a wide range of biotic and abiotic stresses. Epichloë species include many interspecific hybrids with allodiploid-like genomes, which may provide the potential for combined traits or recombination to generate new traits. Though circumstantial evidence suggests that such interspecific hybrids might have arisen from nuclear fusion events following vegetative hyphal fusion between different Epichloë strains, this hypothesis has not been addressed empirically. Here, we investigated vegetative hyphal fusion and subsequent nuclear behavior in Epichloë species. A majority of Epichloë strains, especially those having a sexual stage, underwent self vegetative hyphal fusion. Vegetative fusion also occurred between two hyphae from different Epichloë strains. Though Epichloë spp. are uninucleate fungi, hyphal fusion resulted in two nuclei stably sharing the same cytoplasm, which might ultimately lead to nuclear fusion. In addition, protoplast fusion experiments gave rise to uninucleate putative hybrids, which apparently had two markers, one from each parent within the same nucleus. These results are consistent with the notion that interspecific hybrids arise from vegetative hyphal fusion. However, we also discuss additional factors, such as post-hybridization selection, that may be important to explain the recognized prevalence of hybrids in Epichloë species.

No MeSH data available.


Related in: MedlinePlus

Vegetative hyphal fusion of E. festucae Fl1 in the tall fescue leaf sheath.Confocal micrographs of DIC optics, aniline blue staining showing fungal hyphae, Alexa Fluor 488-conjugated wheat germ agglutinin (WGA-AF) showing septa, and overlaid images with aniline blue staining pseudocolored in red. (A) Arrows point septa in two short hyphae connecting two hyphae extending in parallel. (B) Two hyphae (arrows) connected by a short hypha (arrowhead) which presumably underwent vegetative hyphal fusion. Locations of all three hyphae correspond to outlines of plant cells (compare DIC and aniline blue images). Bars represent 20 μm.
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pone.0121875.g003: Vegetative hyphal fusion of E. festucae Fl1 in the tall fescue leaf sheath.Confocal micrographs of DIC optics, aniline blue staining showing fungal hyphae, Alexa Fluor 488-conjugated wheat germ agglutinin (WGA-AF) showing septa, and overlaid images with aniline blue staining pseudocolored in red. (A) Arrows point septa in two short hyphae connecting two hyphae extending in parallel. (B) Two hyphae (arrows) connected by a short hypha (arrowhead) which presumably underwent vegetative hyphal fusion. Locations of all three hyphae correspond to outlines of plant cells (compare DIC and aniline blue images). Bars represent 20 μm.

Mentions: VHF is also found in endophytic (in planta) hyphae of E. festucae [27]. A clear example is shown in Fig 3A, where two hyphae running in parallel are connected by two short hyphae (arrows), indicating that at least one of these short hyphae underwent VHF. In another example shown in Fig 3B, two hyphae (arrows) are connected by a short hypha (arrowhead), with all three hyphae corresponding to the outlines of their adjacent plant cells. Note that establishment of such hyphal connection of ca. 20 μm in planta may not necessarily require hyphal chemo-attraction (see discussion).


Vegetative hyphal fusion and subsequent nuclear behavior in Epichloë grass endophytes.

Shoji JY, Charlton ND, Yi M, Young CA, Craven KD - PLoS ONE (2015)

Vegetative hyphal fusion of E. festucae Fl1 in the tall fescue leaf sheath.Confocal micrographs of DIC optics, aniline blue staining showing fungal hyphae, Alexa Fluor 488-conjugated wheat germ agglutinin (WGA-AF) showing septa, and overlaid images with aniline blue staining pseudocolored in red. (A) Arrows point septa in two short hyphae connecting two hyphae extending in parallel. (B) Two hyphae (arrows) connected by a short hypha (arrowhead) which presumably underwent vegetative hyphal fusion. Locations of all three hyphae correspond to outlines of plant cells (compare DIC and aniline blue images). Bars represent 20 μm.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4383479&req=5

pone.0121875.g003: Vegetative hyphal fusion of E. festucae Fl1 in the tall fescue leaf sheath.Confocal micrographs of DIC optics, aniline blue staining showing fungal hyphae, Alexa Fluor 488-conjugated wheat germ agglutinin (WGA-AF) showing septa, and overlaid images with aniline blue staining pseudocolored in red. (A) Arrows point septa in two short hyphae connecting two hyphae extending in parallel. (B) Two hyphae (arrows) connected by a short hypha (arrowhead) which presumably underwent vegetative hyphal fusion. Locations of all three hyphae correspond to outlines of plant cells (compare DIC and aniline blue images). Bars represent 20 μm.
Mentions: VHF is also found in endophytic (in planta) hyphae of E. festucae [27]. A clear example is shown in Fig 3A, where two hyphae running in parallel are connected by two short hyphae (arrows), indicating that at least one of these short hyphae underwent VHF. In another example shown in Fig 3B, two hyphae (arrows) are connected by a short hypha (arrowhead), with all three hyphae corresponding to the outlines of their adjacent plant cells. Note that establishment of such hyphal connection of ca. 20 μm in planta may not necessarily require hyphal chemo-attraction (see discussion).

Bottom Line: Epichloë species (including the former genus Neotyphodium) are fungal symbionts of many agronomically important forage grasses, and provide their grass hosts with protection from a wide range of biotic and abiotic stresses.Epichloë species include many interspecific hybrids with allodiploid-like genomes, which may provide the potential for combined traits or recombination to generate new traits.However, we also discuss additional factors, such as post-hybridization selection, that may be important to explain the recognized prevalence of hybrids in Epichloë species.

View Article: PubMed Central - PubMed

Affiliation: The Samuel Roberts Noble Foundation, Plant Biology Division, 2510 Sam Noble Parkway, Ardmore, Oklahoma 73401, United States of America.

ABSTRACT
Epichloë species (including the former genus Neotyphodium) are fungal symbionts of many agronomically important forage grasses, and provide their grass hosts with protection from a wide range of biotic and abiotic stresses. Epichloë species include many interspecific hybrids with allodiploid-like genomes, which may provide the potential for combined traits or recombination to generate new traits. Though circumstantial evidence suggests that such interspecific hybrids might have arisen from nuclear fusion events following vegetative hyphal fusion between different Epichloë strains, this hypothesis has not been addressed empirically. Here, we investigated vegetative hyphal fusion and subsequent nuclear behavior in Epichloë species. A majority of Epichloë strains, especially those having a sexual stage, underwent self vegetative hyphal fusion. Vegetative fusion also occurred between two hyphae from different Epichloë strains. Though Epichloë spp. are uninucleate fungi, hyphal fusion resulted in two nuclei stably sharing the same cytoplasm, which might ultimately lead to nuclear fusion. In addition, protoplast fusion experiments gave rise to uninucleate putative hybrids, which apparently had two markers, one from each parent within the same nucleus. These results are consistent with the notion that interspecific hybrids arise from vegetative hyphal fusion. However, we also discuss additional factors, such as post-hybridization selection, that may be important to explain the recognized prevalence of hybrids in Epichloë species.

No MeSH data available.


Related in: MedlinePlus