Gtari Maher, Dawson Jeffrey O
Laboratoire Microorganismes et Biomolécules Actives, Département de Biologie, Faculté des Sciences de Tunis, 2092 Tunis, Tunisia.
Department of Natural Resources and Environmental Sciences, 1316 Plant Sciences Laboratory, University of Illinois at Urbana-Champaign, 1201 South Dorner Drive, Urbana, IL 61801, USA.
Funct Plant Biol. 2011 Sep;38(9):653-661. doi: 10.1071/FP11009.
A compilation and synthesis of information derived from plant databases and other sources on the occurrence, diversity and geographic distribution of actinorhizal plants in Africa is presented in this review. Actinorhizal plants are a specific group of non-leguminous, woody dicots having symbiotic, nitrogen-fixing root nodules that are induced on roots of actinorhizal plant species by soil actinomycetes of the genus Frankia. There is a lack of basic information on actinorhizal plants in Africa compared with other major land masses in the world. Results indicate that most, if not all, African countries and climatic regions have native or introduced actinorhizal species. A synthesis of available information indicates that there are six families, nine genera and 38 reported species of actinorhizal plants in Africa. Of these, 21 species are native and 17 are exotic. The families and corresponding number of species in each genus are: Betulaceae (native Alnus glutinosa (1), exotic Alnus (2)); Casuarinaceae (exotic Casuarina (5), exotic Allocasuarina (3), exotic Gymnostoma deplancheana (1)); Coriariaceae (native Coriaria myrtifolia (1)); Myricaceae (native Morella (19), exotic Morella cerifera (1)); Rhamnaceae (exotic Ceanothus caeruleus (1), exotic Colletia paradoxa (1)); and Elaeagnaceae (exotic Eleaegnus angustifolia (1)). Four reports of native, actinorhizal Ceanothus species in Africa found in the database were determined to be false, instead, being non-actinorhizal species. Widespread plantings of exotic Casuarinaceae have been introduced into tropical and arid zones of Africa as multipurpose trees, especially in arid regions where native species do not occur. There is a diverse assemblage of native species of Morella in Africa, mostly shrubs or small trees, which provide medicine, other useful chemicals and wildlife habitat. Many native Morella species are isolated in montane islands, apparently leading to greater speciation than in Eurasia from where the genus migrated into Africa. The current status and knowledge of African actinorhizal plants indicates a need to focus research on their biogeography, biology, ecology, genetics and use.
本综述介绍了从植物数据库和其他来源收集并综合的有关非洲放线菌根植物的发生、多样性和地理分布的信息。放线菌根植物是一类特殊的非豆科木本双子叶植物，它们具有共生固氮根瘤，这些根瘤由弗兰克氏菌属的土壤放线菌在放线菌根植物物种的根上诱导形成。与世界上其他主要大陆相比，非洲缺乏有关放线菌根植物的基础信息。结果表明，大多数（如果不是全部的话）非洲国家和气候区域都有本土或引进的放线菌根物种。综合现有信息表明，非洲有6个科、9个属和38种已报道的放线菌根植物。其中，21种是本土物种，17种是外来物种。各科及其所属各属的相应物种数量如下：桦木科（本土欧洲桤木1种，外来桤木属2种）；木麻黄科（外来木麻黄属5种，外来异木麻黄属3种，外来平枝裸孔木1种）；马桑科（本土马桑1种）；杨梅科（本土杨梅属19种，外来蜡杨梅1种）；鼠李科（外来蓝花鼠李1种，外来多刺鼠李1种）；胡颓子科（外来沙枣1种）。数据库中关于非洲本土放线菌根鼠李属物种的4份报告被确定为错误信息，实际上它们是非放线菌根物种。外来木麻黄科植物已被广泛种植到非洲的热带和干旱地区，作为多功能树木，特别是在没有本土物种的干旱地区。非洲有多种本土杨梅属物种，大多为灌木或小树，它们提供药用、其他有用化学物质和野生动物栖息地。许多本土杨梅属物种孤立地分布在山地岛屿上，这显然导致了比该属从欧亚大陆迁移到非洲时更大程度的物种形成。非洲放线菌根植物的现状和知识表明，有必要将研究重点放在它们的生物地理学、生物学、生态学、遗传学和用途上。
