Plant Hormones

Auxins- They have morphogen like characteristics. Auxins control many growth and behaviorial processes in plants. The pattern of auxin distrubuted throughout the plant affects the elongation during the process of the stem or root growing. A plant uses auxin to react to external conditions and adjust to them so it is like a nervous system for the plant. Auxin also plas a minor role in intiating flowering and the devleopment of reproductive organs. Auxins have an effect on phototropism, geotropism, hydrotropism.  Uneven distribution  of the hormone and a lack of homeostasis results in tissue growth problems. Auxins can also have an effect on cell division if cytokinins are also present.

Healthy Plant with auxin vs. one with aauxin-signal transduction mutation

Abscisic acid- These are hormones that play a significant role in bud dormancy. ABA regulated signaling also plays a part in the reaction of plants to environmental stress issues and pathogens. ABA can slow growth in the buds during dormancy. It can also directs leaves to grow a scale type shell to protect buds during the winter. ABA can also regulate the plant's transpiration rate so it doesn't lose a lot of water when it needs the water. ABA can be transported within leaves and to the roots through the xylem.

Ethylene- This hormone is actually a gaseous hormone. It is important for the production of fruit from the plant. It causes the fruit to ripen. In the agricultural industry this hormone is often distrbuted so that the fruit is forced to ripen. This hormone also is involved in the opening of flowers and the shedding of leaves.