Laboratoire Commun de Microbiologie IRD/UCAD/ISRA, (LCM), Centre de Recherche de Bel Air, Dakar, Sénégal.
Mycorrhiza. 2012 Jan;22(1):1-29. doi: 10.1007/s00572-011-0415-x. Epub 2011 Oct 12.
The diversity, ecology and function of ectomycorrhizal (EM) fungi and ectomycorrhizas (ECMs) on tropical African tree species are reviewed here. While ECMs are the most frequent mycorrhizal type in temperate and boreal forests, they concern an economically and ecologically important minority of plants in African tropical forests. In these African tropical forests, ECMs are found mainly on caesalpionioid legumes, Sarcolaenaceae, Dipterocarpaceae, Asterpeiaceae, Phyllantaceae, Sapotaceae, Papilionoideae, Gnetaceae and Proteaceae, and distributed in open, gallery and rainforests of the Guineo-Congolian basin, Zambezian Miombo woodlands of East and South-Central Africa and Sudanian savannah woodlands of the sub-sahara. Overall, EM status was confirmed in 93 (26%) among 354 tree species belonging to EM genera. In addition, 195 fungal taxa were identified using morphological descriptions and sequencing of the ML5/ML6 fragment of sporocarps and ECMs from West Africa. Analyses of the belowground EM fungal communities mostly based on fungal internal transcribed spacer sequences of ECMs from Continental Africa, Madagascar and the Seychelles also revealed more than 350 putative species of EM fungi belonging mainly to 18 phylogenetic lineages. As in temperate forests, the /russula-lactarius and /tomentella-thelephora lineages dominated EM fungal flora in tropical Africa. A low level of host preference and dominance of multi-host fungal taxa on different African adult tree species and their seedlings were revealed, suggesting a potential for the formation of common ectomycorrhizal networks. Moreover, the EM inoculum potential in terms of types and density of propagules (spores, sclerotia, EM root fragments and fragments of mycelia strands) in the soil allowed opportunistic root colonisation as well as long-term survival in the soil during the dry season. These are important characteristics when choosing an EM fungus for field application. In this respect, Thelephoroid fungal sp. XM002, an efficient and competitive broad host range EM fungus, possessed these characteristics and appeared to be a good candidate for artificial inoculation of Caesalps and Phyllanthaceae seedlings in nurseries. However, further efforts should be made to assess the genetic and functional diversity of African EM fungi as well as the EM status of unstudied plant species and to strengthen the use of efficient and competitive EM fungi to improve production of ecologically and economically important African multipurpose trees in plantations.
本文综述了热带非洲树种外生菌根（EM）真菌和外生菌根（ECM）的多样性、生态学和功能。虽然 ECM 是温带和北方森林中最常见的菌根类型，但它们仅涉及非洲热带森林中具有经济和生态重要性的少数植物。在这些非洲热带森林中，ECM 主要存在于金合欢豆科、Sarcolaenaceae、龙脑香科、Asterpeiaceae、叶下珠科、山榄科、豆科、Gnetaceae 和柏科的植物上，并分布于几内亚-刚果盆地的开阔、长廊和雨林、东非和中非的赞比西河 Miombo 林地以及撒哈拉以南的苏丹草原林地。总体而言，在属于 EM 属的 354 种树种中，有 93 种（26%）被确认具有 EM 状态。此外，通过对来自西非的子实体和 ECM 的 ML5/ML6 片段进行形态描述和测序，鉴定了 195 种真菌类群。对基于 ECM 内部转录间隔区序列的地下 EM 真菌群落的分析主要基于来自非洲大陆、马达加斯加和塞舌尔的 EM 真菌，也揭示了属于 18 个系统发育谱系的 350 多种潜在的 EM 真菌。与温带森林一样，/russula-lactarius 和 /tomentella-thelephora 谱系在热带非洲的 EM 真菌区系中占主导地位。揭示了不同非洲成年树种及其幼苗上低水平的宿主偏好和多宿主真菌类群的优势，表明形成共同外生菌根网络的潜力。此外，土壤中繁殖体（孢子、菌核、外生菌根根片段和菌丝片段）的类型和密度所代表的 EM 接种潜力允许机会性根系定殖以及在旱季期间在土壤中的长期生存。这些是在田间应用中选择 EM 真菌时的重要特征。在这方面，高效且具有广泛宿主范围的外生菌根真菌 XM002 具有这些特征，似乎是人工接种金合欢属和叶下珠科幼苗的良好候选物。然而，应进一步努力评估非洲 EM 真菌的遗传和功能多样性以及未研究植物物种的 EM 状态，并加强对高效且具有竞争力的 EM 真菌的利用，以提高人工林具有生态和经济重要性的非洲多用树种的产量。
