Fungal symbioses in roots of the seagrass genus Posidonia: distribution, phenotypic and genetic variability and potential ecophysiological significance

Kořeny rostlin hostí široké spektrum endofytických hub, od parazitických přes neutralistické až po mutualistické mykorhizní houby. V terestrickém prostředí jsou tyto houby poměrně dobře prozkoumány, ale co se týče vodních rostlin, naše znalosti jsou značně omezené. Obzvláště málo je známo o houbách asociovaných s kořeny mořských trav, jediné skupiny cévnatých rostlin trvale ponořených pod mořskou hladinou. Zaměřili jsme se na studium kořenů mořské trávy posidonie Neptunovy, endemického druhu Středozemního moře. V jejích kořenech jsme zjistili přítomnost endofytických hub. S využitím mikroskopických technik jsme studovali jejich morfologii. Izolací a následnými molekulárními analýzami mykobiontů jsme pak odhalili jejich taxonomickou příslušnost. V celém rozsáhlém areálu Středozemního moře od Španělska po jižní Turecko jsme zaznamenali výskyt symbiózy kořenů p. Neptunovy s tmavě zbarvenou septovanou houbou. Tato houba se vyznačuje charakteristickými strukturami, kterými jsou povrchové hyfy tvořící někdy souvislý plášť nebo hustou hyfovou síť, dále vnitrokořenové hyfy rostoucí mezi buňkami, řidčeji i uvnitř buněk, a konečně vnitrobuněčná mikrosklerocia. Celkově se tento endofyt podobá dark septate endophytes (DSE), běžným symbiontům terestrických i sladkovodních rostlin. V několika následných studiích jsme se...Plant roots host a wide spectrum of endophytic fungi ranging from parasites through neutralistic fungi to mutualistic mycorrhizal fungi. In most of terrestrial ecosystems, these groups of symbiotic fungi are well documented. However, much less is known about fungal endophytes of aquatic plants, especially the only group of submerged marine plants, seagrasses. We focused on roots of the seagrass species Posidonia oceanica which is a Mediterranean endemite. Its roots hosted an abundant presence of endophytic fungi. We examined the roots using optical and electron microscopy in order to study its morphology. We isolated the mycobionts and determined their taxonomic classification. A specific symbiosis of P. oceanica roots and dark coloured septate fungus has been recorded all over a vast area of the Mediterranean spreading from southern Spain to south Turkey. The fungus forms distinctive and typical structures: superficial hyphae occasionally forming hyphal sheaths or dense hyphal nets, intraradical hyphae colonizing extracellular space and, occasionally, primary cortex cells, and finally intracellular microsclerotia. The colonization pattern of the fungi resembles dark septate endophytes (DSE), group of fungi commonly found in roots of both terrestrial and freshwater plants. In our following studies, we...Katedra experimentální biologie rostlinDepartment of Experimental Plant BiologyPřírodovědecká fakultaFaculty of Scienc

Mycorrhizal and endophytic roots of aquatic plants

Interactions between fungi and plants can be found all around us. We would hardly find a plant neither containing a single hypha in its rhizosphere nor infested with a fungal pathogen. Whereas interactions of these organisms are well and described in terrestrial ecosystems, situation below the water level is completely different. The status of aquatic fungi and their relation to aquatic plants is to date not clear at all regarding difficulties of reaching them and huge value of terrestric interactions, which occupy most of the experts. All the basic plant-fungus interactions have been detected also underwater. As well as on the land, the most widespread aquatic mycorrhizal association is arbuscular mycorrhiza. On the contrary, the other well known mycorrhiza types such as orchid or ericoid mycorrhiza do not occur in the aquatic environment where their hosts are absent. On the other hand, endophytism is relatively frequent. Ascomycetous fungi with dark septate hyphae, collectively being referred to as "dark septate endophytes" (DSE), seem to be as abundant in the water as on the land. Additionally, aquatic plants are being challenged by numerous fungal parasites. AMF may play an important role in nutrient uptake of some plants from the aquatic environment. However, many species of aquatic plants are..

Mycorrhizal and endophytic roots of aquatic plants

Interakce mezi houbou a rostlinou jsou přítomné všude kolem nás. Jen stěží bychom hledali rostlinu, která nemá v rhizosféře ani jednu hyfu nebo není napadena houbovým patogenem. Zatímco v terestrických ekosystémech jsou interakce těchto organismů zmapovány kvalitně a systematicky, pod vodní hladinou je situace zcela jiná. Vzhledem k obtížné přístupnosti podvodních ekosystémů a také obrovskému ekonomickému významu interakcí terestrických, které zaměstnávají většinu odborníků z oboru, jsou vodní houby a jejich vztah k rostlinám dosud ne zcela probádaným tématem. Ve vodním prostředí byly objeveny všechny základní typy interakcí rostlina-houba. Z mutualistických, tedy mykorhizních asociací je stejně jako na souši nejrozšířenější arbuskulární mykorhiza, naopak ostatní známé typy mykorhiz jako orchideoidní nebo erikoidní se pod vodou nevyskytují vzhledem k absenci příslušných hostitelských rostlin. Široce rozšířený je endofytismus. Běžně jsou v kořenech vodních rostlin pozorovány i vřeckovýtrusé houby s tmavými přepážkovanými hyfami, které se označují se souhrnným pojmem "dark septate endophytes" (DSE). Zdá se, že jsou stejně rozšířeny ve vodě, jako na souši. V neposlední řadě napadá vodní rostliny mnoho houbových endoparazitů. AMH mohou ve vodním prostředí hrát důležitou roli v příjmu živin u některých...Interactions between fungi and plants can be found all around us. We would hardly find a plant neither containing a single hypha in its rhizosphere nor infested with a fungal pathogen. Whereas interactions of these organisms are well and described in terrestrial ecosystems, situation below the water level is completely different. The status of aquatic fungi and their relation to aquatic plants is to date not clear at all regarding difficulties of reaching them and huge value of terrestric interactions, which occupy most of the experts. All the basic plant-fungus interactions have been detected also underwater. As well as on the land, the most widespread aquatic mycorrhizal association is arbuscular mycorrhiza. On the contrary, the other well known mycorrhiza types such as orchid or ericoid mycorrhiza do not occur in the aquatic environment where their hosts are absent. On the other hand, endophytism is relatively frequent. Ascomycetous fungi with dark septate hyphae, collectively being referred to as "dark septate endophytes" (DSE), seem to be as abundant in the water as on the land. Additionally, aquatic plants are being challenged by numerous fungal parasites. AMF may play an important role in nutrient uptake of some plants from the aquatic environment. However, many species of aquatic plants are...Katedra experimentální biologie rostlinDepartment of Experimental Plant BiologyPřírodovědecká fakultaFaculty of Scienc

Fungal symbioses in roots of the seagrass genus Posidonia: distribution, phenotypic and genetic variability and potential ecophysiological significance

Plant roots host a wide spectrum of endophytic fungi ranging from parasites through neutralistic fungi to mutualistic mycorrhizal fungi. In most of terrestrial ecosystems, these groups of symbiotic fungi are well documented. However, much less is known about fungal endophytes of aquatic plants, especially the only group of submerged marine plants, seagrasses. We focused on roots of the seagrass species Posidonia oceanica which is a Mediterranean endemite. Its roots hosted an abundant presence of endophytic fungi. We examined the roots using optical and electron microscopy in order to study its morphology. We isolated the mycobionts and determined their taxonomic classification. A specific symbiosis of P. oceanica roots and dark coloured septate fungus has been recorded all over a vast area of the Mediterranean spreading from southern Spain to south Turkey. The fungus forms distinctive and typical structures: superficial hyphae occasionally forming hyphal sheaths or dense hyphal nets, intraradical hyphae colonizing extracellular space and, occasionally, primary cortex cells, and finally intracellular microsclerotia. The colonization pattern of the fungi resembles dark septate endophytes (DSE), group of fungi commonly found in roots of both terrestrial and freshwater plants. In our following studies, we..

Mycorrhizal and endophytic roots of aquatic plants

Interactions between fungi and plants can be found all around us. We would hardly find a plant neither containing a single hypha in its rhizosphere nor infested with a fungal pathogen. Whereas interactions of these organisms are well and described in terrestrial ecosystems, situation below the water level is completely different. The status of aquatic fungi and their relation to aquatic plants is to date not clear at all regarding difficulties of reaching them and huge value of terrestric interactions, which occupy most of the experts. All the basic plant-fungus interactions have been detected also underwater. As well as on the land, the most widespread aquatic mycorrhizal association is arbuscular mycorrhiza. On the contrary, the other well known mycorrhiza types such as orchid or ericoid mycorrhiza do not occur in the aquatic environment where their hosts are absent. On the other hand, endophytism is relatively frequent. Ascomycetous fungi with dark septate hyphae, collectively being referred to as "dark septate endophytes" (DSE), seem to be as abundant in the water as on the land. Additionally, aquatic plants are being challenged by numerous fungal parasites. AMF may play an important role in nutrient uptake of some plants from the aquatic environment. However, many species of aquatic plants are..

Ecophysiological significance of root-fungus symbioses in Mediterranean seagrasses

Seagrasses are the only group of submerged plants that are permanently growing in marine environment. They play an important role in the sea bottom ecosystem. Seagrasses are primary producers capable of accumulation and deposition of carbon. They influence water flow at the sea bottom and form symbioses with variety of organisms. Our knowledge of symbiotic interactions of seagrasses is still limited even though several studies of the topic have been carried out in recent years. Unlike most of terrestrial plants, seagrasses are generally considered as plants that do not form any specific associations with mycorrhizal or endophytic fungi. Surprisingly, we have discovered a novel fungal endophytic association in roots of Mediterranean endemic seagrass species Posidonia oceanica (L.) Delile. Morphology of this symbiotic fungi strongly resembles common symbiotic fungi of terrestrial plants, dark septate endophytes (DSE). We sampled roots of P. oceanica in large area of the Mediterranean from southeastern Spain to Albania and described range and taxonomical classification of the endophyte using microscopy, in vitro cultivation and molecular determination. Roots of P. oceanica in whole area of study are colonized by mere two endophytic fungal species. Over 90 % of the fungal symbionts belong to a single..

Extensive sampling and high-throughput sequencing reveal Posidoniomyces atricolor gen. et sp. nov. (Aigialaceae, Pleosporales) as the dominant root mycobiont of the dominant Mediterranean seagrass Posidonia oceanica

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