Nature－氮从“丛枝菌根真菌”向寄主植物的转移机制

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氮从大多数陆地植物根上的“丛枝菌根真菌”向寄主植物的转移的一种以前人们不
知道的机制的发现表明，这种共生关系在全球氮循环中可能是一个比我们以前所认
为的重要得多的因素。该机制涉及根外面的真菌对无机氮的吸收、在真菌内转化成
氨基酸、然后作为铵离子从真菌的菌丝体转移进植物中。（Letter p. 819）“丛
枝菌根真菌”识别寄主过程中的的第一件事被认为是菌丝分枝。现在，从“百脉
根”分离出的一种Strigolactone（5-deoxy-strigol）被发现是诱发分枝的物质。
Strigolactones是根代谢物，以前是作为根寄生杂草的种子发芽促进剂被分离出来
的。现在的这一发现突出显示了植物和真菌之间的密切关系，也许还能为农业和自
然生态系统中有益真菌共生体和破坏性寄生杂草的控制提供一个新战略。

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Nature 435, 824-827 (9 June 2005) | doi: 10.1038/nature03608

Plant sesquiterpenes induce hyphal branching in arbuscular mycorrhizal fungi
Kohki Akiyama1,2, Ken-ichi Matsuzaki1 and Hideo Hayashi1

Top of pageArbuscular mycorrhizal (AM) fungi form mutualistic, symbiotic associations with the roots of more than 80% of land plants1. The fungi are incapable of completing their life cycle in the absence of a host root. Their spores can germinate and grow in the absence of a host, but their hyphal growth is very limited. Little is known about the molecular mechanisms that govern signalling and recognition between AM fungi and their host plants. In one of the first stages of host recognition, the hyphae of AM fungi show extensive branching in the vicinity of host roots before formation of the appressorium2, 3, 4, the structure used to penetrate the plant root. Host roots are known to release signalling molecules that trigger hyphal branching5, 6, 7, but these branching factors have not been isolated. Here we have isolated a branching factor from the root exudates of Lotus japonicus and used spectroscopic analysis and chemical synthesis to identify it as a strigolactone, 5-deoxy-strigol. Strigolactones are a group of sesquiterpene lactones, previously isolated as seed-germination stimulants for the parasitic weeds Striga and Orobanche8. The natural strigolactones 5-deoxy-strigol, sorgolactone and strigol, and a synthetic analogue, GR24, induced extensive hyphal branching in germinating spores of the AM fungus Gigaspora margarita at very low concentrations.

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下面是引用qiusuo于2005-06-13 19:50发表的:
Nature 435, 824-827 (9 June 2005) | doi: 10.1038/nature03608

Plant sesquiterpenes induce hyphal branching in arbuscular mycorrhizal fungi
Kohki Akiyama1,2, Ken-ichi Matsuzaki1 and Hideo Hayashi1

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