Dynamics of periarbuscular membranes visualized with a fluorescent phosphate transporter in arbuscular mycorrhizal roots of rice [Oryza sativa]

• Published in: Plant and cell physiology Vol. 51; no. 3; pp. 341 - 353
• Main Authors: Kobae, Y., Nagoya Univ. (Japan), Hata, S
• Format: Journal Article
• Language: English
• Published: Japan Oxford University Press 01.03.2010
• Subjects: Arbuscule; Cell Membrane - genetics; Cell Membrane - metabolism; Cell Membrane - microbiology; FLUORESCENCE; FLUORESCENCIA; Freshwater; Gigaspora rosea; Glomus mosseae; Green Fluorescent Proteins - genetics; Green Fluorescent Proteins - metabolism; http://www.fao.org/aos/agrovoc#c_10935; http://www.fao.org/aos/agrovoc#c_27619; http://www.fao.org/aos/agrovoc#c_5023; http://www.fao.org/aos/agrovoc#c_5438; http://www.fao.org/aos/agrovoc#c_6651; In planta imaging; Microscopy, Confocal; Microscopy, Fluorescence; MYCORHIZE; MYCORRHIZAE; Mycorrhizae - physiology; Mycorrhizal symbiosis; Oryza - genetics; Oryza - metabolism; Oryza - microbiology; ORYZA SATIVA; Phosphate Transport Proteins - genetics; Phosphate Transport Proteins - metabolism; Phosphate transporter; Plant Proteins - genetics; Plant Proteins - metabolism; Plant Roots - genetics; Plant Roots - metabolism; Plant Roots - microbiology; PLANTAS TRANSGENICAS; PLANTE TRANSGENIQUE; Plants, Genetically Modified - genetics; Plants, Genetically Modified - metabolism; Plants, Genetically Modified - microbiology; RACINE; RAICES; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; ROOTS; Symbiosis; TRANSGENIC PLANTS
• ISSN: 0032-0781; 1471-9053
• DOI: 10.1093/pcp/pcq013

In arbuscular mycorrhizal (AM) symbiosis, host plants supply photosynthates to AM fungi and, in return, they receive inorganic nutrients such as phosphate from finely branched fungal arbuscules. Plant cortical cells envelope arbuscules with periarbuscular membranes that are continuous with the plant plasma membranes. We prepared transgenic rice (Oryza sativa) plants that express a fusion of green fluorescent protein with rice AM-inducible phosphate transporter, OsPT11-GFP, and grew them with AM fungi. The fluorescence of the fusion transporter was observed in the arbuscule branch domain, where active nutrient exchange seems to occur. In contrast, a signal was not detected around intracellular hyphal coils on colonization by either Glomus mosseae or Gigaspora rosea, making the difference between Arum- and Paris-type mycorrhizae ambiguous. We also invented a simple device involving glass-bottomed Petri dishes for in planta observation of fluorescent proteins in living AM roots with an inverted fluorescence microscope. The plant bodies remain completely intact, avoiding any stressful procedure such as cutting, staining, etc. Since rice roots exhibit a very low level of autofluorescence, the device enabled dear time-lapse imaging to analyze the formation, function and degeneration of arbuscules. In cortical cells, arbuscules seemed to be functional for only 2 - 3 d. Suddenly, the arbuscular branches became fragile and they shrank. At this stage, however, the periarbuscular membranes appeared intact. Then, the fluorescence of the transporter disappeared within only 2.5 - 5.5 h. The collapse of arbuscules occurred in the subsequent several days. Thus, our device has a great advantage for investigation of dynamic features of AM symbiosis.