Diédhiou A G, Bâ A M, Sylla S Nd, Dreyfus B, Neyra M, Ndoye I
Laboratoire de Microbiologie des Sols Tropicaux, Centre de recherche IRD/ISRA, BP 1386, Dakar, Senegal.
Mycorrhiza. 2004 Oct;14(5):313-22. doi: 10.1007/s00572-003-0276-z. Epub 2003 Nov 21.
This study was conducted to evaluate the competitiveness and effectiveness of Thelephoroid fungal sp. ORS.XM002 against native ectomycorrhizal fungal species colonizing potted Afzelia africana seedlings during 3 months of growth in different forest soils collected from under mature trees. Using morphotyping and restriction fragment length polymorphism (RFLP) analysis of the nuclear rDNA internal transcribed spacer (ITS), we were able to distinguish the introduced Thelephoroid fungal sp. ORS.XM002 among native ectomycorrhizal fungal species that form ectomycorrhizae in A. africana seedlings. The morphotype (MT) of the introduced fungus showed some color variation, with a shift from light- to dark-brown observed from younger to older mycorrhizal tips. We were able to differentiate the ITS type xm002 of the introduced fungus from the 14 ITS-RFLP types characterizing the 9 native MT that occurred in forest soils. The frequency of ITS type xm002 ranged from 40% to 49% depending on the forest soil used, and was always higher than those of ITS types from native dark-brown MT that occurred in inoculated seedlings 3 months after inoculation. We considered Thelephoroid fungal sp. ORS.XM002 to be responsible for stimulation of mycorrhizal colonization of inoculated A. africana seedlings when compared with control seedlings in forest soils. This fungus appeared to be more effective in increasing the root dry weight of A. africana seedlings. To identify the unknown introduced fungal species and native MT, we sequenced the ML5/ML6 region of the mitochondrial large subunit rRNA. Sequence analysis showed that these fungi belong to three ML5/ML6 groups closely related to the Cortinarioid, Thelephoroid, and Sclerodermataceous taxa. The molecular evidence for the persistence of Thelephoroid fungal sp. ORS.XM002 despite competition from native fungi argues in favor of using this fungus with A. africana in nursery soil conditions in Senegal.
本研究旨在评估革菌属真菌ORS.XM002在取自成熟树下不同森林土壤中生长3个月的盆栽非洲崖豆树苗上，相对于定殖于其上的本地外生菌根真菌物种的竞争力和有效性。通过对核糖体DNA内部转录间隔区（ITS）进行形态分型和限制性片段长度多态性（RFLP）分析，我们能够在与非洲崖豆树苗形成外生菌根的本地外生菌根真菌物种中区分出引入的革菌属真菌ORS.XM002。引入真菌的形态型（MT）呈现出一些颜色变化，从较年轻到较老的菌根尖端观察到从浅褐色到深褐色的转变。我们能够将引入真菌的ITS类型xm002与表征森林土壤中出现的9种本地MT的14种ITS - RFLP类型区分开来。ITS类型xm002的频率根据所用森林土壤的不同在40%至49%之间，并且在接种3个月后，其频率始终高于接种幼苗中出现的本地深褐色MT的ITS类型的频率。与森林土壤中的对照幼苗相比，我们认为革菌属真菌ORS.XM002促成了接种的非洲崖豆树苗菌根定殖的增加。这种真菌似乎在增加非洲崖豆树苗的根干重方面更有效。为了鉴定未知的引入真菌物种和本地MT，我们对线粒体大亚基rRNA的ML5/ML6区域进行了测序。序列分析表明，这些真菌属于与丝膜菌科、革菌属和硬皮马勃类群密切相关的三个ML5/ML6组。尽管存在来自本地真菌的竞争，但革菌属真菌ORS.XM002仍能持续存在的分子证据支持在塞内加尔的苗圃土壤条件下将这种真菌与非洲崖豆一起使用。
