Microtubules of the mycorrhizal fungus Glomus intraradices in symbiosis with tomato roots

2001 ◽  
Vol 79 (3) ◽  
pp. 307-313 ◽  
Author(s):  
S Timonen ◽  
F A Smith ◽  
S E Smith

In this study the presence and orientation of fungal microtubules were recorded in arbuscular mycorrhizal symbiosis for the first time. Visualization of the fungal microtubules was achieved by using a protocol specifically labelling only fungal tubulins. Microtubules of external mycelium, intraradical hyphae, arbuscules, and vesicles of the arbuscular mycorrhizal fungus Glomus intraradices Schenck & Smith were examined when in symbiosis with tomato (Lycopersicon esculentum Mill.). Microtubules were organized as bundles in both external and intraradical hyphae. The bundles of microtubules extended directly from intraradical hyphae into the arbuscules, where the microtubules remained as bundles in the larger hyphae. In the fine fungal branches of the arbuscules, microtubules were seen as thinner filaments. Fungal microtubules were seen to connect the intraradical hyphae and arbuscules. In addition, microtubules of adjacent arbuscules could continue directly from one arbuscule to another. Microtubules reached to the basal cone of each vesicle, but the live vesicles, containing many nuclei, seemed devoid of any microtubular labelling.Key words: cytoskeleton, endomycorrhiza, filamentous fungi, tomato, tubulin, Zygomycota.

2012 ◽  
Vol 49 (4) ◽  
pp. 313-321 ◽  
Author(s):  
Kinga A. Sędzielewska ◽  
Katja Vetter ◽  
Rüdiger Bode ◽  
Keith Baronian ◽  
Roland Watzke ◽  
...  

Botany ◽  
2008 ◽  
Vol 86 (9) ◽  
pp. 1009-1019 ◽  
Author(s):  
Maria Manjarrez ◽  
F. Andrew Smith ◽  
Petra Marschner ◽  
Sally E. Smith

For the first time, the phenotypes formed in the reduced mycorrhizal colonization (rmc) Solanum lycopersicum  L. (tomato) mutant with different arbuscular mycorrhizal (AM) fungi were used to explore the potential of different fungal structures to support development of external fungal mycelium and spores. The life cycle of AM fungi with rmc was followed for up to 24 weeks. Results showed that production of external mycelium was slight and transitory for those fungi that did not penetrate the roots of rmc (Pen–) ( Glomus intraradices DAOM181602 and Glomus etunicatum ). For fungi that penetrated the root epidermis and hypodermis (Coi–, Glomus coronatum and Scutellospora calospora ) the mycelium produced varied in size, but was always smaller than with the wild-type 76R. Spores were formed by these fungi with 76R but not with rmc. The only fungus forming a Myc+ phenotype with rmc, G. intraradices WFVAM23, produced as much mycelium with rmc as with 76R. We observed lipid accumulation in hyphae and vesicles in both plant genotypes with this fungus. Mature spores were formed with 76R. However, with rmc, spores remained small and (presumably) immature for up to 24 weeks. We conclude that significant carbon transfer from plant to fungus can occur in Coi– interactions with rmc in which no cortical colonization occurs. We speculate that both carbon transfer and root signals are required for mature spores to be produced.


2002 ◽  
Vol 15 (4) ◽  
pp. 360-367 ◽  
Author(s):  
Juan M. Ruiz-Lozano ◽  
Carlos Collados ◽  
Rosa Porcel ◽  
Rosario Azcón ◽  
JoséM. Barea

A cDNA library was constructed with RNA from Glomus intraradices-colonized lettuce roots and used for differential screening. This allowed the identification of a cDNA (Gi-1) that was expressed only in mycorrhizal roots and was of fungal origin. The function of the gene product is unknown, because Gi-1 contained a complete open reading frame that was predicted to encode a protein of 157 amino acids which only showed little homology with glutamine synthetase from Helicobacter pylori. The time-course analysis of gene expression during the fungal life cycle showed that Gi-1 was expressed only during the mycorrhizal symbiosis and was not detected in dormant or germinating spores of G. intraradices. P fertilization did not significantly change the pattern of Gi-1 expression compared with that in the unfertilized treatment, whereas N fertilization (alone or in combination with P) considerably enhanced the Gi-1 transcript accumulation. This increase in gene expression correlated with plant N status and growth under such conditions. The possible role of the Gi-1 gene product in intermediary N metabolism of arbuscular mycorrhizal symbiosis is further discussed.


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