The endosymbiosis-induced genes ENOD40 and CCS52a are involved in endoparasitic-nematode interactions in Medicago truncatula.
Plants associate with a wide range of mutualistic and parasitic biotrophic organisms. Here, we investigated whether beneficial plant symbionts and biotrophic pathogens induce distinct or overlapping regulatory pathways in Medicago truncatula. The symbiosis between Sinorhizobium meliloti and this plant results in the formation of nitrogen-fixing root nodules requiring the activation of specific genes in the host plant. We studied expression patterns of nodule-expressed genes after infection with the root-knot nematode Meloidogyne incognita. Two regulators induced during nodule organogenesis, the early nodulin gene ENOD40 involved in primordium formation and the cell cycle gene CCS52a required for cell differentiation and endoreduplication, are expressed in galls of the host plant. Expression analysis of promoter-uidA fusions indicates an accumulation of CCS52a transcripts in giant cells undergoing endoreduplication, while ENOD40 expression is localized in surrounding cell layers. Transgenic plants overexpressing ENOD40 show a significantly higher number of galls. In addition, out of the 192 nodule-expressed genes tested, 38 genes were upregulated in nodules at least threefold compared with control roots, but only two genes, nodulin 26 and cyclin D3, were found to be induced in galls. Taken together, these results suggest that certain events, such as endoreduplication, cell-to-cell communication with vascular tissues, or water transport, might be common between giant cell formation and nodule development.
Favery
Bruno
B
Unité Interactions Plantes-Microorganismes et Santé Végétale, INRA, 123, Antibes, France.
Complainville
Arnaud
A
Vinardell
Jose Maria
JM
Lecomte
Philippe
P
Vaubert
Danièle
D
Mergaert
Peter
P
Kondorosi
Adam
A
Kondorosi
Eva
E
Crespi
Martin
M
Abad
Pierre
P
D000818:Animals; D018797:Cell Cycle Proteins / Q000235:genetics*; D056743:Cyclin D3; D016213:Cyclins / Q000235:genetics; D020869:Gene Expression Profiling / Q000379:methods; D018506:Gene Expression Regulation, Plant; D006790:Host-Parasite Interactions; D029902:Medicago / Q000235:genetics* / Q000382:microbiology / Q000469:parasitology; D008565:Membrane Proteins / Q000235:genetics; D009348:Nematoda / Q000254:growth & development*; D010940:Plant Proteins / Q000235:genetics*; D018517:Plant Roots / Q000382:microbiology / Q000469:parasitology; D010941:Plant Tumors / Q000235:genetics; D030821:Plants, Genetically Modified; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated / Q000502:physiology*; D016962:Sinorhizobium meliloti / Q000254:growth & development; D013559:Symbiosis / Q000235:genetics*
D018797:Cell Cycle Proteins; D056743:Cyclin D3; D016213:Cyclins; C405430:ENOD40 RNA; C489058:MTN6 protein, Medicago truncatula; D008565:Membrane Proteins; D010940:Plant Proteins; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated; C121327:ccs52 protein, Medicago sativa; C045625:nodulin