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Karahara I, Umemura K, Soga Y, Akai Y, Bando T, Ito Y, Tamaoki D, Uesugi K, Abe J, Yamauchi D, Mineyuki Y. Demonstration of osmotically dependent promotion of aerenchyma formation at different levels in the primary roots of rice using a 'sandwich' method and X-ray computed tomography. Ann Bot 2012; 110:503-9. [PMID: 22499856 PMCID: PMC3394647 DOI: 10.1093/aob/mcs075] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
BACKGROUND AND AIMS The effect of environmental factors on the regulation of aerenchyma formation in rice roots has been discussed for a long time, because aerenchyma is constitutively formed under aerated conditions. To elucidate this problem, a unique method has been developed that enables sensitive detection of differences in the development of aerenchyma under two different environmental conditions. The method is tested to determine whether aerenchyma development in rice roots is affected by osmotic stress. METHODS To examine aerenchyma formation both with and without mannitol treatment in the same root, germinating rice (Oryza sativa) caryopses were sandwiched between two agar slabs, one of which contained 270 mm of mannitol. The roots were grown touching both slabs and were thereby exposed unilaterally to osmotic stress. As a non-invasive approach, refraction contrast X-ray computed tomography (CT) using a third-generation synchrotron facility, SPring-8 (Super photon ring 8 GeV, Japan Synchrotron Radiation Research Institute), was used to visualize the three-dimensional (3-D) intact structure of aerenchyma and its formation in situ in rice roots. The effects of unilateral mannitol treatment on the development of aerenchyma were quantitatively examined using conventional light microscopy. KEY RESULTS Structural continuity of aerenchyma was clearly visualized in 3-D in the primary root of rice and in situ using X-ray CT. Light microscopy and X-ray CT showed that the development of aerenchyma was promoted on the mannitol-treated side of the root. Detailed light microscopic analysis of cross-sections cut along the root axis from the tip to the basal region demonstrated that aerenchyma developed significantly closer to the root tip on the mannitol-treated side of the root. CONCLUSIONS Continuity of the aerenchyma along the rice root axis was morphologically demonstrated using X-ray CT. By using this 'sandwich' method it was shown that mannitol promoted aerenchyma formation in the primary roots of rice.
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Affiliation(s)
- Ichirou Karahara
- Department of Biology, Graduate School of Science and Engineering, University of Toyama, Toyama 930-8555, Japan
- For correspondence. E-mail
| | - Konomi Umemura
- Department of Biology, Faculty of Science, University of Toyama, Toyama 930-8555, Japan
| | - Yuumi Soga
- Department of Biology, Faculty of Science, University of Toyama, Toyama 930-8555, Japan
| | - Yuki Akai
- Department of Biology, Faculty of Science, University of Toyama, Toyama 930-8555, Japan
| | - Tadafumi Bando
- Department of Biology, Graduate School of Science and Engineering, University of Toyama, Toyama 930-8555, Japan
| | - Yuko Ito
- Department of Biology, Faculty of Science, University of Toyama, Toyama 930-8555, Japan
| | - Daisuke Tamaoki
- Department of Life Science, Graduate School of Life Science, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280, Japan
| | - Kentaro Uesugi
- Japan Synchrotron Radiation Research Institute, 1-1 Koto, Mikazuki-cho, Sayo-gun, Hyogo 679-5198, Japan
| | - Jun Abe
- AE-Bio, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Daisuke Yamauchi
- Department of Life Science, Graduate School of Life Science, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280, Japan
| | - Yoshinobu Mineyuki
- Department of Life Science, Graduate School of Life Science, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280, Japan
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