The wall loosening of guard cells differs from other types of plant cells. However, the regulation of wall loosening during stomatal movement is poorly understood. VfEXPA1 is an α-expansin gene cloned from Vicia faba...The wall loosening of guard cells differs from other types of plant cells. However, the regulation of wall loosening during stomatal movement is poorly understood. VfEXPA1 is an α-expansin gene cloned from Vicia faba epidermal strips. Expression of VfEXPA1 is regulated by darkness and submergence, and is not affected by light and abscisic acid (ABA). In situ hybridization showed that VfEXPA1 is expressed primarily in the guard cells. Overexpression of VfEXPA1 in transgenic tobacco accelerated light-induced stomatal opening, and increased both transpiration and photosynthetic rates under favorable growth conditions. Our results indicate the guard cell-expressed expansin VfEXPA1 plays an important role in regulation of stomatal opening.展开更多
Observation under an electron microscope reveals that in closed and open stomata of V. faba, the aver-age volume of particles in guard cell vacuoles (GCV) reduces about 3 orders in magnitude, while the distribution de...Observation under an electron microscope reveals that in closed and open stomata of V. faba, the aver-age volume of particles in guard cell vacuoles (GCV) reduces about 3 orders in magnitude, while the distribution density of the particles increases about 2 orders of magnitude. By using the method of the ratio of fluorescent emissions with laser scanning confocal microscopy, the monitoring to sto-mata opening shows that during 10 to 30 s before the first distinguishable aperture of stomata, there is a change of pH in GCV about -0.5 units. A quick stomatal opening immedi-ately follows the changes of pH in GCV to reach a steady aperture about 12 mm in 100200 s. This work proposes a model for the osmoregulation in GCV for stomatal opening. The proposed osmoregulation is related to the disaggregation of some polymerized particles inside GCV, which is probably induced by a -DpH in the vacuole. This model describes a process of osmoregulation that avoids the massive energy consuming transportation across cell membranes, which is a foundation of the current chemiosmotic hypothesis. This model is a supplement to the multiple controlling hypothesis for the stomatal movement, which widens research principle ideas for other quick movements in plants.展开更多
Guard cell wall properties are important in stomatal movement. Previous research focused on the structure and anatomy of guard cell walls, but little is known about the physical changes that take place within the wall...Guard cell wall properties are important in stomatal movement. Previous research focused on the structure and anatomy of guard cell walls, but little is known about the physical changes that take place within the walls during stomatal opening and closure. In this work, we investigate the volumetric elastic modulus (ε) of the guard cell wall at different pH values during stomatal opening in Vicia faba epidermal strips using a cell pressure probe. The volumetric elastic modulus of the guard cell wall decreased from 7.098 to 5.690 MPa when the pH of the cell wall decreased from 8.60 to 6.50. It is easier for guard cells to change their volume at a lower volumetric elastic modulus during stomatal movement. The results are suggestive of a putative role for pH in the regulation of stomatal movement.展开更多
基金supported by the National Basic Research Program of China (2006CB100100, 2003CB114300)the National Natural Science Foundation of China (30370129, 30421002)
文摘The wall loosening of guard cells differs from other types of plant cells. However, the regulation of wall loosening during stomatal movement is poorly understood. VfEXPA1 is an α-expansin gene cloned from Vicia faba epidermal strips. Expression of VfEXPA1 is regulated by darkness and submergence, and is not affected by light and abscisic acid (ABA). In situ hybridization showed that VfEXPA1 is expressed primarily in the guard cells. Overexpression of VfEXPA1 in transgenic tobacco accelerated light-induced stomatal opening, and increased both transpiration and photosynthetic rates under favorable growth conditions. Our results indicate the guard cell-expressed expansin VfEXPA1 plays an important role in regulation of stomatal opening.
基金the National Natural Science Foundation of China (Grant Nos. 39870075 and 30170451) and The Major State Basic Research Development Program of China (Grant No. G19990117)
文摘Observation under an electron microscope reveals that in closed and open stomata of V. faba, the aver-age volume of particles in guard cell vacuoles (GCV) reduces about 3 orders in magnitude, while the distribution density of the particles increases about 2 orders of magnitude. By using the method of the ratio of fluorescent emissions with laser scanning confocal microscopy, the monitoring to sto-mata opening shows that during 10 to 30 s before the first distinguishable aperture of stomata, there is a change of pH in GCV about -0.5 units. A quick stomatal opening immedi-ately follows the changes of pH in GCV to reach a steady aperture about 12 mm in 100200 s. This work proposes a model for the osmoregulation in GCV for stomatal opening. The proposed osmoregulation is related to the disaggregation of some polymerized particles inside GCV, which is probably induced by a -DpH in the vacuole. This model describes a process of osmoregulation that avoids the massive energy consuming transportation across cell membranes, which is a foundation of the current chemiosmotic hypothesis. This model is a supplement to the multiple controlling hypothesis for the stomatal movement, which widens research principle ideas for other quick movements in plants.
基金supported by the National Natural Science Foundation of China (39870075 and 39600090)
文摘Guard cell wall properties are important in stomatal movement. Previous research focused on the structure and anatomy of guard cell walls, but little is known about the physical changes that take place within the walls during stomatal opening and closure. In this work, we investigate the volumetric elastic modulus (ε) of the guard cell wall at different pH values during stomatal opening in Vicia faba epidermal strips using a cell pressure probe. The volumetric elastic modulus of the guard cell wall decreased from 7.098 to 5.690 MPa when the pH of the cell wall decreased from 8.60 to 6.50. It is easier for guard cells to change their volume at a lower volumetric elastic modulus during stomatal movement. The results are suggestive of a putative role for pH in the regulation of stomatal movement.
