Medicago truncatulais a plant model to study symbiosis with its bacterial partnerSinorhizobium melilotiand a host for parasitic root-knot nematodes, such asMeloidogyne incognita. Root-knot nematodes induce the redifferenciation of root cells into specialized feeding cells called “giant cells”. Hyperplasia and hypertrophy of the surrounding cells lead to the formation of root galls. Bacteria induce the development of root nodules and chronically infect plant cells from zone II* before differentiating into atmospheric nitrogen fixing bacteroids. Using laser-assisted microdissection, we specifically monitored, at the cell level, Medicago gene expression in nodule zone II cells and in giant cells and their surrounding cells. We revealed an important reprogramming of several pathways in both interactions, which may play key roles in nodule and gall neoformatio. In addition, detailed analysis of glutathione (GSH) and homoglutathione (hGSH, a legume GSH analogue) metabolism demonstrated the importance of these compounds for the success of both interactions inM. truncatula. Depletion of (h)GSH content impaired nematode egg mass formation and modified the sex ratio. Gene expression and metabolomic analyses of (h)GSH-depleted galls suggest that these major antioxidant molecules have a key role in the regulation of giant cell metabolism.
*zone II: infection zone
- Damiani, I., Baldacci-Cresp, F., Hopkins, J., Andrio, E., Balzergue, S., Lecomte, P., Puppo, A., Abad, P., Favery*, B. and Hérouart*, D (co-corresponding authors) (2012). Plant Genes Involved in Harbouring Symbiotic Rhizobia or Pathogenic Nematode.New Phytologist, 194: 511–522.
- Fabien Baldacci-Cresp, F., Chang, C., Maucourt, M., Deborde, C., Hopkins, J., Lecomte, P., Brouquisse, R., Moing, A., Abad, P., Hérouart, D., Puppo, A., Favery, B. and Frendo, P. (2012). (Homo)glutathione Deficiency Impairs Root-knot NematodeDevelopment inMedicago truncatula.PLoS Pathogens8(1): e1002471.