BIOL-1507EL Lecture Notes - Lecture 13: Meristem, Apical Dominance, Cytokinesis
9 Nov 2017
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Plant response to internal and external signals (plant hormones) Plants often respond to external and internal stimuli with exchanges in their growth patterns. Some of the external factors that regulate growth are light, day light, gravity, and temperature. Among the principal of internal factors that regulate growth are plant hormone. A hormone in a chemical messenger produced in small amounts, by one part of the body, that is active in a different part of the body. 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:449)ord (cid:373)ea(cid:374)i(cid:374)g to (cid:858)e(cid:454)(cid:272)ite(cid:859) So far five classes (six) of plant hormones, have been positively identified: auxin, gibberellin, c(cid:455)toki(cid:374)es(cid:859, abscisic acid, ethylene, bassano steroids** Auxin: the most naturally occurring auxin is indolactic acid (iaa) produced in shoot meristems, young leaves, and flowers and fruit. Early researchers observed that the plant bends toward light, a phenomena, or known as (cid:862)phototropis(cid:373)(cid:863)
