Trépanier Martin, Bécard Guillaume, Moutoglis Peter, Willemot Claude, Gagné Serge, Avis Tyler J, Rioux Jacques-André
Centre de Recherche en Horticulture, Pavillon de l'Envirotron, Université Laval, Québec G1K 7P4, Canada.
Appl Environ Microbiol. 2005 Sep;71(9):5341-7. doi: 10.1128/AEM.71.9.5341-5347.2005.
Lipids are the major form of carbon storage in arbuscular-mycorrhizal fungi. We studied fatty acid synthesis by Glomus intraradices and Gigaspora rosea. [(14)C]Acetate and [(14)C]sucrose were incorporated into a synthetic culture medium to test fatty acid synthetic ability in germinating spores (G. intraradices and G. rosea), mycorrhized carrot roots, and extraradical fungal mycelium (G. intraradices). Germinating spores and extraradical hyphae could not synthesize 16-carbon fatty acids but could elongate and desaturate fatty acids already present. The growth stimulation of germinating spores by root exudates did not stimulate fatty acid synthesis. 16-Carbon fatty acids (16:0 and 16:1) were synthesized only by the fungi in the mycorrhized roots. Our data strongly suggest that the fatty acid synthase activity of arbuscular-mycorrhizal fungi is expressed exclusively in the intraradical mycelium and indicate that fatty acid metabolism may play a major role in the obligate biotrophism of arbuscular-mycorrhizal fungi.
脂质是丛枝菌根真菌中碳储存的主要形式。我们研究了根内球囊霉和玫瑰巨孢囊霉的脂肪酸合成。将[¹⁴C]乙酸盐和[¹⁴C]蔗糖加入合成培养基中，以测试发芽孢子（根内球囊霉和玫瑰巨孢囊霉）、菌根化胡萝卜根和根外真菌菌丝体（根内球囊霉）中的脂肪酸合成能力。发芽孢子和根外菌丝体不能合成16碳脂肪酸，但可以延长和去饱和已存在的脂肪酸。根分泌物对发芽孢子的生长刺激并未刺激脂肪酸合成。只有菌根化根中的真菌能合成16碳脂肪酸（16:0和16:1）。我们的数据有力地表明，丛枝菌根真菌的脂肪酸合酶活性仅在根内菌丝体中表达，并表明脂肪酸代谢可能在丛枝菌根真菌的专性生物营养中起主要作用。
