Epinasty

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As epinasty stronger growth is called adaxial tissues of plants compared to abaxialem tissue. Under physiological conditions, the relationship between epinasty and geotropism determines the angle between the shoot axis and leaves or side shoots. When waterlogged , epinasty causes a pathological condition in which the leaves grow downwards due to increased, one-sided ethylene production , since the adaxial (upper) side of the petiole grows faster than the abaxial. This makes the plant look wilted; the turgor (leaf or cellular pressure) is normal.

The waterlogging is perceived in the roots of the plant, from where ACC, a precursor of ethylene in the Yang cycle , reaches the leaves via the perspiration suction in the conductive tissue. Here it can act as ethylene converted by the ACC oxidase.

Epinasty causes an increased production of phytohormones ( auxin ), a suppressive effect in the growth of weak shoots compared to the main shoots.