Pfeffer Philip E, Douds David D, Bücking Heike, Schwartz Daniel P, Shachar-Hill Yair
USDA ARS Eastern Regional Research Center, 600 E. Mermaid Lane, Wyndmoor, PA 19038, USA.
Michigan State University, Plant Biology Department, East Lansing, MI 48824-1312, USA.
New Phytol. 2004 Sep;163(3):617-627. doi: 10.1111/j.1469-8137.2004.01152.x.
• Carbon transfer from fungus to plant in the arbuscular mycorrhizal (AM) symbiosis has been reported, but its significance and even its existence have been called into question and the issue remains controversial. We investigated carbon movement from fungus to plant and from one mycorrhizal root system to another via a common AM fungal network in monoxenic cultures to avoid limitations of some previous studies. • C and C labeled substrates were supplied to functioning in vitro AM mycorrhizas between Ri T-DNA transformed carrot (Daucus carota) roots and Glomus intraradices to follow carbon movement into and between host and fungal metabolite pools. • Fungal triacylglycerol and trehalose were labeled when permeant substrates were supplied to the extraradical mycelium (ERM), but host-specific compounds in the roots did not become labeled. When labeled glucose was provided to a donor root system, label moved to recipient roots via a common AM fungal network but remained in fungal compounds. • We conclude that carbon flow in the AM symbiosis is normally unidirectional from plant to fungus and that while carbon is translocated by the fungus from one metabolically active root system to another, it remains within the intraradical mycelium (IRM).
• 已有报道称在丛枝菌根（AM）共生体系中存在从真菌到植物的碳转移，但这一过程的重要性乃至其是否真的存在都受到了质疑，该问题仍存在争议。我们在单菌培养体系中，通过一个共同的AM真菌网络，研究了碳从真菌到植物以及从一个菌根根系到另一个菌根根系的转移情况，以避免以往一些研究存在的局限性。
• 将13C和14C标记的底物提供给发根农杆菌Ri T-DNA转化的胡萝卜（胡萝卜属）根系与根内球囊霉之间起作用的体外AM菌根，以追踪碳进入宿主和真菌代谢库以及在两者之间的转移情况。
• 当向根外菌丝体（ERM）提供可渗透底物时，真菌三酰甘油和海藻糖被标记，但根中的宿主特异性化合物未被标记。当向供体根系提供标记葡萄糖时，标记物通过共同的AM真菌网络转移到受体根系，但仍保留在真菌化合物中。
• 我们得出结论，AM共生体系中的碳流通常是从植物到真菌的单向流动，并且虽然碳被真菌从一个代谢活跃的根系转移到另一个根系，但它仍保留在根内菌丝体（IRM）中。
