BIOL-1507EL Lecture Notes - Lecture 5: Meristem, Gibberellin, Auxin
21 Jan 2018
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Document Summary
Generally plant hormones are produced by the meristematic regions. The (cid:449)ord (cid:862)hor(cid:373)o(cid:374)e(cid:863) is deri(cid:448)ed fro(cid:373) a greek (cid:448)er(cid:271) (cid:373)ea(cid:374)i(cid:374)g to ex(cid:272)ite. So far, five classes of plant hormones have been positively identified: auxin, gibberellins, cytokinis, abcisic acid, eythylene, brassino steroids. These hormones can have a profound effect on the growth and development of plant organs. Reaction to a hormone usually depends not so much on the absolute amount of that hormone as on its relative concentration compared with other hormones. Hormones that promote growth : auxin, the most naturally occurring auxin is indolacetic acid (iaa, produced in shoot meristems, young leaves, and flowers and fruits. Early researchers observed that plants bend towards the light, a phenomenon called phototropism. Darwins experiment around 1881: charles and son francis reported an experiment with grass and oat seedlings. If the coleoptile of the seedling was kept intact, the seedling would bend toward a unidirectional light source.
