Turgor pressure

[2] Generally, turgor pressure is caused by the osmotic flow of water and occurs in plants, fungi, and bacteria.

Other mechanisms include transpiration, which results in water loss and decreases turgidity in cells.

In vascular plants, turgor pressure is responsible for apical growth of features such as root tips[10] and pollen tubes.

This function is important as a plant response under drought conditions[12] (seeing as turgor pressure is maintained), and for cells which need to accumulate solutes (i.e. developing fruits).

[13] It has been recorded that the petals of Gentiana kochiana and Kalanchoe blossfeldiana bloom via volatile turgor pressure of cells on the plant's adaxial surface.

[11] During processes like anther dehiscence, it has been observed that drying endothecium cells cause an outward bending force which leads to the release of pollen.

The pollen tube of lilies have a mean turgor pressure of 0.21 MPa when growing during this process.

[14] In fruits such as Impatiens parviflora, Oxalia acetosella and Ecballium elaterium, turgor pressure is the method by which seeds are dispersed.

[9] It has been concluded that loss of turgor pressure within the leaves of Mimosa pudica is responsible for the plant's reaction when touched.

Other factors such as changes in osmotic pressure, protoplasmic contraction and increase in cellular permeability have been observed to affect this response.

When touched, the pulvinus is activated and exudes contractile proteins, which in turn increases turgor pressure and closes the leaves of the plant.

In species such as Saprolegnia ferax, Magnaporthe grisea and Aspergillus oryzae, immense turgor pressures have been observed in their hyphae.

The study showed that they could penetrate substances like plant cells, and synthetic materials such as polyvinyl chloride.

[20] In observations of this phenomenon, it is noted that invasive hyphal growth is due to turgor pressure, along with the coenzymes secreted by the fungi to invade said substrates.

Throughout these organisms' life cycle, carefully controlled turgor pressure is responsible for cell expansion and for the release of sperm, but not for processes such as seta growth.

When using this method, gravity and matric potential are considered to be negligible, since their values are generally either negative or close to zero.

[30] The pressure bomb technique was developed by Scholander et al., reviewed by Tyree and Hammel in their 1972 publication, in order to test water movement through plants.

It is usually used on higher plant tissues but was not used to measure turgor pressure until Hüsken and Zimmerman improved the method.

There have been studies[36][37] which show that negative cell pressures can exist in xerophytic plants, but a paper by M. T. Tyree explores whether this is possible, or a conclusion based on misinterpreted data.

He concludes that claims of negative turgor pressure values were incorrect and resulted from mis-categorization of "bound" and "free" water in a cell.

Despite this analysis and interpretation of data, negative turgor pressure values are still used within the scientific community.

[38] A hypothesis presented by M. Harold and colleagues suggests that tip growth in higher plants is amoebic in nature, and is not caused by turgor pressure as is widely believed, meaning that extension is caused by the actin cytoskeleton in these plant cells.