caa a22 4500 477109381 CHVBK 20180405111604.0 cr unu---uuuuu 170330e19960301xx s 000 0 eng 10.1007/BF00029283 doi (NATIONALLICENCE)springer-10.1007/BF00029283 Water in aerenchyma spaces in roots. A fast diffusion path for solutes [Elektronische Daten] [C. van der Weele, M. Canny, M. McCully] During a study of the diffusivity of sulphorhodamine G in the cortical apoplast of maize roots widely discrepant rates were found between different samples. In roots which had developed large aerenchyma spaces, the diffusion in some regions was very fast, indistinguishable from the rate in water. In other regions the rate was as much as 100 times slower. Examination of frozen intact roots with the cryo-scanning electron microscope showed the presence of liquid filling some of the aerenchyma spaces, while other spaces of the same root contained air. X-ray microanalysis of the liquid (for oxygen) showed that the liquid was water with few detectable ions. Similar liquid was present in small intercellular spaces within the spoke-like radial files of cells between the large spaces, or between remnants of collapsed cell walls at the edges of the large spaces. It is proposed that regions of roots with high diffusivity are those in which some of the aerenchyma spaces are filled with water. In seeking the origin of this liquid, the progress of aerenchyma formation could be followed in the frozen tissues. The first change observed in a group of contiguous cells was a loss of vacuolar solutes and of cell turgor. Next the walls broke apart and collapsed back onto the surrounding turgid cells leaving a volume of ion-poor liquid. The liquid was probably not that found in some aerenchyma spaces of the mature roots, because the final stage of space formation was a loss of the liquid, leaving an air filled cavity surrounded by a composite lining formed from the collapsed walls of the broken cells. It is likely that the liquid in the spaces of mature aerenchyma is exuded from the remaining living cortical cells at times when the root turgor is high. This would be consistent with several recent studies which have shown periodic exudation of water from the surface of turgid roots. The spasmodic occurrence of root cortex tissue with enhanced diffusivity would have important implications for the transport of nutrient ions across the root. Kluwer Academic Publishers, 1996 aerenchyma nationallicence cryo-microscopy nationallicence intercellular water nationallicence maize nationallicence root cortex nationallicence solute diffusion nationallicence Zea mays nationallicence CSEM : cryo-scanning electron microscope nationallicence EDX : energy dispersive X-ray microanalysis nationallicence SR-G : sulphorhodamine G nationallicence van der Weele C. Department of Plant Ecology and Evolutionary Biology, University of Utrecht, P.O. Box 800.84, 3508 TB, Utrecht, The Netherlands aut Canny M. Biology Department, Carleton University, 1125 Colonel By Drive, KIS 5B6, Ottawa, Canada aut McCully M. Biology Department, Carleton University, 1125 Colonel By Drive, KIS 5B6, Ottawa, Canada aut Plant and Soil Kluwer Academic Publishers; gopher://gopher.wkap.nl 184/1(1996-03-01), 131-141 0032-079X 184:1<131 1996 184 11104 https://doi.org/10.1007/BF00029283 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00029283 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- van der Weele C. Department of Plant Ecology and Evolutionary Biology, University of Utrecht, P.O. Box 800.84, 3508 TB, Utrecht, The Netherlands aut NATIONALLICENCE 700 1- Canny M. Biology Department, Carleton University, 1125 Colonel By Drive, KIS 5B6, Ottawa, Canada aut NATIONALLICENCE 700 1- McCully M. Biology Department, Carleton University, 1125 Colonel By Drive, KIS 5B6, Ottawa, Canada aut NATIONALLICENCE 773 0- Plant and Soil Kluwer Academic Publishers; gopher://gopher.wkap.nl// 184/1(1996-03-01), 131-141 0032-079X 184:1<131 1996 184 11104 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer