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发表于 2005-6-13 19:50:39
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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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