Hydraulic Conductivity and Aquaporins of Cortical Cells in Gravitropically Bending Roots of Pisum sativum L.
We examined the differential elongation of gravitropically bending roots of Pisum sativum L. in terms of cell enlargement and water uptake by cells in the growing tissue. Hydraulic conductivity between the elongating and mature tissues (Lp) was estimated from the equation G = A × Lp × Δψ, where G is...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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Taylor & Francis Group
2005-01-01
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| Series: | Plant Production Science |
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| Online Access: | http://dx.doi.org/10.1626/pps.8.515 |
| _version_ | 1818909170544410624 |
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| author | Naoko Miyamoto Maki Katsuhara Taiichiro Ookawa Kunihiro Kasamo Tadashi Hirasawa |
| author_facet | Naoko Miyamoto Maki Katsuhara Taiichiro Ookawa Kunihiro Kasamo Tadashi Hirasawa |
| author_sort | Naoko Miyamoto |
| collection | DOAJ |
| description | We examined the differential elongation of gravitropically bending roots of Pisum sativum L. in terms of cell enlargement and water uptake by cells in the growing tissue. Hydraulic conductivity between the elongating and mature tissues (Lp) was estimated from the equation G = A × Lp × Δψ, where G is the water-uptake rate, A is the surface area of a single cell and Δψ is the driving force. The rate of entry of water into a cell was estimated from the rate of increase in the volumes of cells in the outer cortex, which were calculated from longitudinal sections at given times. Gravitropic bending occurred 1 h after the application of gravi-stimulation and the curvature increased rapidly for the next 3 h. The biggest difference in the partial elongation rate between opposite sides of a root was found in the region 3 to 4 mm from the root tip at the start of stimulation. Cell enlargement rate was 2.8 to 3.8 times greater on the upper side of the root than on the lower side. The water potential and the osmotic potential, in both the elongating and mature tissues, were the same on both sides of the root. Therefore, there was no difference in the driving force for water flow. Hydraulic conductivity was 2.3 to 4.2 times greater on the upper side of the root than on the lower side. There was no difference between the upper and lower sides of the root in the amounts of 19-kD and 24-kD proteins in membrane fractions, which we assumed to be aquaporins (putative aquaporins), as estimated with two preparations of polyclonal antibodies. The differential elongation that occurred during root gravitropism was caused by a difference in Lp. However, the difference in Lp did not appear to be regulated by the concentration in cell membranes of the putative aquaporins. |
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| issn | 1343-943X 1349-1008 |
| language | English |
| last_indexed | 2024-12-19T22:22:39Z |
| publishDate | 2005-01-01 |
| publisher | Taylor & Francis Group |
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| series | Plant Production Science |
| spelling | doaj.art-3a66ac274a7847edaf2295d0d4b07c8f2022-12-21T20:03:36ZengTaylor & Francis GroupPlant Production Science1343-943X1349-10082005-01-018551552410.1626/pps.8.51511644732Hydraulic Conductivity and Aquaporins of Cortical Cells in Gravitropically Bending Roots of Pisum sativum L.Naoko Miyamoto0Maki Katsuhara1Taiichiro Ookawa2Kunihiro Kasamo3Tadashi Hirasawa4Graduate School of Agriculture, Tokyo University of Agriculture and TechnologyResearch Institute for Bioresources, Okayama UniversityGraduate School of Agriculture, Tokyo University of Agriculture and TechnologyResearch Institute for Bioresources, Okayama UniversityGraduate School of Agriculture, Tokyo University of Agriculture and TechnologyWe examined the differential elongation of gravitropically bending roots of Pisum sativum L. in terms of cell enlargement and water uptake by cells in the growing tissue. Hydraulic conductivity between the elongating and mature tissues (Lp) was estimated from the equation G = A × Lp × Δψ, where G is the water-uptake rate, A is the surface area of a single cell and Δψ is the driving force. The rate of entry of water into a cell was estimated from the rate of increase in the volumes of cells in the outer cortex, which were calculated from longitudinal sections at given times. Gravitropic bending occurred 1 h after the application of gravi-stimulation and the curvature increased rapidly for the next 3 h. The biggest difference in the partial elongation rate between opposite sides of a root was found in the region 3 to 4 mm from the root tip at the start of stimulation. Cell enlargement rate was 2.8 to 3.8 times greater on the upper side of the root than on the lower side. The water potential and the osmotic potential, in both the elongating and mature tissues, were the same on both sides of the root. Therefore, there was no difference in the driving force for water flow. Hydraulic conductivity was 2.3 to 4.2 times greater on the upper side of the root than on the lower side. There was no difference between the upper and lower sides of the root in the amounts of 19-kD and 24-kD proteins in membrane fractions, which we assumed to be aquaporins (putative aquaporins), as estimated with two preparations of polyclonal antibodies. The differential elongation that occurred during root gravitropism was caused by a difference in Lp. However, the difference in Lp did not appear to be regulated by the concentration in cell membranes of the putative aquaporins.http://dx.doi.org/10.1626/pps.8.515AquaporinCell elongationGravitropismHydraulic conductivityPisum sativum LWater uptake |
| spellingShingle | Naoko Miyamoto Maki Katsuhara Taiichiro Ookawa Kunihiro Kasamo Tadashi Hirasawa Hydraulic Conductivity and Aquaporins of Cortical Cells in Gravitropically Bending Roots of Pisum sativum L. Plant Production Science Aquaporin Cell elongation Gravitropism Hydraulic conductivity Pisum sativum L Water uptake |
| title | Hydraulic Conductivity and Aquaporins of Cortical Cells in Gravitropically Bending Roots of Pisum sativum L. |
| title_full | Hydraulic Conductivity and Aquaporins of Cortical Cells in Gravitropically Bending Roots of Pisum sativum L. |
| title_fullStr | Hydraulic Conductivity and Aquaporins of Cortical Cells in Gravitropically Bending Roots of Pisum sativum L. |
| title_full_unstemmed | Hydraulic Conductivity and Aquaporins of Cortical Cells in Gravitropically Bending Roots of Pisum sativum L. |
| title_short | Hydraulic Conductivity and Aquaporins of Cortical Cells in Gravitropically Bending Roots of Pisum sativum L. |
| title_sort | hydraulic conductivity and aquaporins of cortical cells in gravitropically bending roots of pisum sativum l |
| topic | Aquaporin Cell elongation Gravitropism Hydraulic conductivity Pisum sativum L Water uptake |
| url | http://dx.doi.org/10.1626/pps.8.515 |
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