Salt tolerant plants - Salt entry into root cells

As over 20% of all arable land is affected by high salt levels much research work has been carried out into understanding the mechanisms involved in how plants deal with salt and increases in salinity. Plants can be categorized into two main types, salt intolerant glycophyte and salt tolerant halophytes.

Arabidopsis thaliana is one of the most used plants in research and although it is a glycophyte it has helped to further the understanding of salt tolerance immensely as salinity stresses and mutations that can overcome these stresses can be investigated.

Mechanisms involved in root cell salt entry

Although plants to not have mechanisms specifically developed for the uptake of salt ions there are many ways in which salt is able to enter the plant cell passively. It therefore follows that In areas of high salinity a greater amount of salt will be took up by the plant.

One of the main ways in which salt is passively took up by plant root cells is via cation channels, these have two main classifications:

1. Voltage dependent cation channels
2. Voltage independent cation channels

With regards to voltage dependent cation channels it is thought that the potassium transporters may act to import sodium ions into the root cells with a low affinity, whilst this is not usually of importance in areas of high salinity, this can result in an high uptake of salt into the plant via the root cells.

Despite the role of potassium channels in salt uptake, it is known that the voltage independent cation channels play a much larger role in salt entry to root cells.

Mechanisms that control salt uptake in root cells

Although there is a gene known as 'salt overly sensitive' that has been shown to be involved as a part of a salt regulation pathway in arabidopsis many other factors act to control the regulation of salt uptake and removal in plants these include:

1. Soil acidity
2. Membrane potential
3. Salt concentration and form
4. the action of plant hormones