Abscission Auxin also plays a role in the abscission of leaves and fruits. Young leaves and fruits produce auxin and so long as they do so, they remain attached to the stem. Soon the petiole or fruit stalk breaks free at this point and the leaf or fruit falls to the ground. Fruit growers often apply auxin sprays to cut down the loss of fruit from premature dropping. Auxins stimulate the formation of adventitious roots in many species.
Adventitious roots grow from stems or leaves rather than from the regular root system of the plant.
Horticulturalists may propagate desirable plants by cutting pieces of stem and placing them base down in moist soil. Eventually adventitious roots grow out at the base of the cutting. The process can often be hastened by treating the cuttings with a solution or powder containing a synthetic auxin. So the distribution on the cell of these two types of transporter establishes which direction auxin travels in. The arrival of auxin at the surface of the cell initiates such immediate responses as changes in movement of ions in and out of the cell through the plasma membrane extension of the cell wall causing elongation of the cell.