Hyperhydricity

hyperhydricity . It is a physiological disorder that can occur in plant tissue culture. This can occur at a lower or higher range. When it occurs with a low range, the main problems of its effects do not exceed those found in the establishment stage. When manifested to a high extent, serious problems can be seen at different stages of in vitro culture .

Symptoms

Hyperhydric tissues are characterized by a glassy appearance, translucent stems and leaves, and distortion of their organs. The development and survival of hyperhydric tissues is very low.
Symptoms of hyperhydricity are not always perceived directly with the human eye. Visual symptoms may occur because the plant is more susceptible or because cultural conditions are more adverse. Examples of more adverse conditions are:

• the concentration of cytokinins too high
• high water holding capacity
• the container is too closed
• low concentration of gelling agent

The symptoms are not identical in all plants and morphological, anatomical and biochemical level types occur.

Causes

Many causes have been mentioned. However, many of these factors will only act to induce hyperhydricity when other conditions in the growing system are not optimized. Factors that can be considered:

• Explants : species, cultivars; time elapsed since last subculture; number of subcultures; cut type; placement in the middle.
• Medium : concentration and type of gelling agent; presence of a layer of liquid; the level and type of cytokinin; salt concentration.
• Container : Concentration and composition of gases.
• Environment : temperature; light intensity and quality; RH.

way to avoid it

Symptoms of hyperhydricity can be minimized by:

• Culture medium ingredients : solidified media with a higher concentration of a gelling agent, as well as the use of a gelling agent with superior gel strength; decreased cytokinin concentration .
• Characteristics of the container : a closure device not too hermetic, as well as membranes permeable to gases, allowing greater exchange of water vapor and other gases with the surrounding environment.
• Environmental conditions : cooling of the bottom of the culture vessels; increased light intensity; cold storage in a medium without 6-benzylaminopurine (6-BAP) .