Plant genes involved in harbouring symbiotic rhizobia or pathogenic nematodes

• Published in: The New phytologist Vol. 194; no. 2; pp. 511 - 522
• Main Authors: Damiani, Isabelle, Baldacci‐Cresp, Fabien, Hopkins, Julie, Andrio, Emilie, Balzergue, Sandrine, Lecomte, Philippe, Puppo, Alain, Abad, Pierre, Favery, Bruno, Hérouart, Didier
• Format: Journal Article
• Language: English
• Published: Oxford, UK New Phytologist Trust 01-04-2012; Blackwell Publishing Ltd; Wiley Subscription Services, Inc; Wiley
• Subjects: Alfalfa; Animals; Bacteria; Body organs; Cells; Endocytosis; Gall; Gene expression; Gene Expression Profiling; Gene Expression Regulation, Plant; Genes; Genes, Plant - genetics; giant cell; Giant cells; Hormones; Host specificity; Infections; laser microdissection; Lasers; Life Sciences; Medicago - genetics; Medicago - microbiology; Medicago - parasitology; Medicago truncatula; Meloidogyne incognita; Metabolism; Multigene Family; Nematoda; Nematoda - physiology; Nematodes; nitrogen‐fixing symbiosis; nodule; Nodules; Oligonucleotide Array Sequence Analysis; Organs; Pathogens; Phytopathology and phytopharmacy; Plant cells; Plant interaction; Plant roots; Plants; Reproducibility of Results; Rhizobium - physiology; Root Nodules, Plant - genetics; root‐knot nematode (RKN); Sinorhizobium meliloti; Specificity; Symbionts; Symbiosis; Symbiosis - genetics; Transcription, Genetic; transcriptome; Transcriptome - genetics; Vegetal Biology; Microdissection laser; Medicago truncatula; RELATION PLANTE-MICROORGANISME; pathogene; transcriptome; nodule; Fabaceae; Meloidogyne incognita; root-knot nematode; laser microdissection; giant cell; nitrogen-fixing symbiosis; Sinorhizobium meliloti
• ISSN: 0028-646X; 1469-8137
• DOI: 10.1111/j.1469-8137.2011.04046.x

The establishment and development of plant–microorganism interactions involve impressive transcriptomic reprogramming of target plant genes. The symbiont (Sinorhizobium meliloti) and the root knot-nematode pathogen (Meloidogyne incognita) induce the formation of new root organs, the nodule and the gall, respectively.
Using laser-assisted microdissection, we specifically monitored, at the cell level, Medicago gene expression in nodule zone II cells, which are preparing to receive rhizobia, and in gall giant and surrounding cells, which play an essential role in nematode feeding and constitute the typical root swollen structure, respectively.
We revealed an important reprogramming of hormone pathways and C1 metabolism in both interactions, which may play key roles in nodule and gall neoformation, rhizobia endocytosis and nematode feeding. Common functions targeted by rhizobia and nematodes were mainly down-regulated, whereas the specificity of the interaction appeared to involve up-regulated genes.
Our transcriptomic results provide powerful datasets to unravel the mechanisms involved in the accommodation of rhizobia and root-knot nematodes. Moreover, they raise the question of host specificity and the evolution of plant infection mechanisms by a symbiont and a pathogen.