Vapyrin, a gene essential for intracellular progression of arbuscular mycorrhizal symbiosis, is also essential for infection by rhizobia in the nodule symbiosis of Medicago truncatula
Intracellular invasion of root cells is required for the establishment of successful endosymbioses in legumes of both arbuscular mycorrhizal (AM) fungi and rhizobial bacteria. In both interactions a requirement for successful entry is the activation of a common signalling pathway that includes five genes required to generate calcium oscillations and two genes required for the perception of the calcium response. Recently, it has been discovered that in Medicago truncatula, the Vapyrin (VPY) gene is essential for the establishment of the arbuscular mycorrhizal symbiosis. Here, we show by analyses of mutants that the same gene is also required for rhizobial colonization and nodulation. VPY encodes a protein featuring a Major Sperm Protein domain, typically featured on proteins involved in membrane trafficking and biogenesis, and a series of ankyrin repeats. Plants mutated in this gene have abnormal rhizobial infection threads and fewer nodules, and in the case of interactions with AM fungi, epidermal penetration defects and aborted arbuscule formation. Calcium spiking in root hairs in response to supplied Nod factors is intact in the vpy-1 mutant. This, and the elevation of VPY transcripts upon application of Nod factors which we show to be dependent on NFP, DMI1, and DMI3, indicates that VPY acts downstream of the common signalling pathway.
Document Type: Research Article
Affiliations: 1: Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK 73401, USA 2: Department of Biology, Area 11, PO Box 373, University of York, York Y010 5YW, UK 3: Department of Disease and Stress Biology, John Innes Centre, Norwich NR4 7UH, UK 4: Department of Plant and Soil Sciences, Oklahoma State University, 368 Agricultural Hall, Stillwater, OK 74078-6028, USA 5: Institut des Sciences du Vegetale, CNRS, Avenue de la Terrasse, 91198 Gif sur Yvette, France
Publication date: January 1, 2011