A diffusible signal from arbuscular mycorrhizal fungi elicits a transient cytosolic calcium elevation in host plant cells

被引:101
作者
Navazio, Lorella [1 ]
Moscatiello, Roberto
Genre, Andrea
Novero, Mara
Baldan, Barbara
Bonfante, Paola
Mariani, Paola
机构
[1] Univ Padua, Dipartimento Biol, I-35131 Padua, Italy
[2] Univ Turin, Ist Protez Plant, Dipartimento Biol Vegetale, Council Nazl Rich, I-10125 Turin, Italy
关键词
D O I
10.1104/pp.106.086959
中图分类号
Q94 [植物学];
学科分类号
071001 ;
摘要
The implication of calcium as intracellular messenger in the arbuscular mycorrhizal ( AM) symbiosis has not yet been directly demonstrated, although often envisaged. We used soybean ( Glycine max) cell cultures stably expressing the bioluminescent Ca 21 indicator aequorin to detect intracellular Ca 21 changes in response to the culture medium of spores of Gigaspora margarita germinating in the absence of the plant partner. Rapid and transient elevations in cytosolic free Ca 21 were recorded, indicating that diffusible molecules released by the mycorrhizal fungus are perceived by host plant cells through a Ca2+-mediated signaling. Similar responses were also triggered by two Glomus isolates. The fungal molecules active in generating the Ca 21 transient were constitutively released in the medium, and the induced Ca 21 signature was not modified by the coculture of germinating spores with plant cells. Even ungerminated spores were able to generate the signaling molecules, as proven when the germination was blocked by a low temperature. The fungal molecules were found to be stable to heat treatment, of small molecular mass (< 3 kD), and, on the basis of extraction with an organic solvent, partially lipophilic. Evidence for the specificity of such an early fungal signal to the AM symbiosis is suggested by the lack of a Ca 21 response in cultured cells of the nonhost plant Arabidopsis ( Arabidopsis thaliana) and by the up-regulation in soybean cells of genes related to Medicago truncatula DMI1, DMI2, and DMI3 and considered essential for the establishment of the AM symbiosis.
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页码:673 / 681
页数:9
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