Differential location of alpha-expansin proteins during the accommodation of root cells to an arbuscular mycorrhizal fungus.
Planta
; 220(6): 889-99, 2005 Apr.
Article
in En
| MEDLINE
| ID: mdl-15605243
ABSTRACT
alpha-Expansins are extracellular proteins that increase plant cell-wall extensibility. We analysed their pattern of expression in cucumber roots in the presence and in the absence of the mycorrhizal fungus, Glomus versiforme. The distribution of alpha-expansins was investigated by use of two polyclonal antibodies (anti-EXPA1 and anti-EXPA2, prepared against two different cucumber alpha-expansins) in immunoblotting, immunofluorescence, and immunogold experiments. Immunoblot results indicate the presence of a 30-kDa band specific for mycorrhizal roots. The two antibodies identify antigens with a different distribution in mycorrhizal roots anti-EXPA1 labels the interface zone, but the plant cell walls only weakly. By contrast, the anti-EXPA2 labels only the plant cell walls. In order to understand the potential role of alpha-expansins during the accommodation of the fungus inside root cells, we prepared semi-thin sections to measure the size of cortical cells and the thickness of cortical cell walls in mycorrhizal and non-mycorrhizal root. Mycorrhizal cortical cells were significantly larger than non-mycorrhizal cells and had thicker cell walls. In double-labelling experiments with cellobiohydrolase-gold complex, we observed that cellulose was co-localized with alpha-expansins. Taken together, the results demonstrate that alpha-expansins are more abundant in the cucumber cell walls upon mycorrhizal infection; we propose that these wall-loosening proteins are directly involved in the accommodation of the fungus by infected cortical cells.
Search on Google
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Plant Proteins
/
Plant Roots
/
Cucumis sativus
/
Mycorrhizae
/
Fungi
Language:
En
Journal:
Planta
Year:
2005
Document type:
Article
Affiliation country:
Italia